When I first started learning about plants I found the number of botanical terms daunting to say the least.  I constantly complained “if you ask 10 botanists to describe a flower shape how many different words will you get for that shape?”  The answer, I said, was “10”.  While that may be a bit of an exaggeration for sure, I have found the number of synonyms in botany astounding. So I started compiling my own botanical dictionary so that I could refer back to it when I came across yet another obscure term. Then what I do is use the terms that I like, usually those that I find most commonly used. 

One day I want to also write a ‘Botanists Thesaurus” to deal with synonyms.  But for now here is my collection of all the botany terms I have come across so far in my own studies. I have started adding synonyms and antonyms but only some definitions have those.  Many of these terms you may never come across, but many you will.  Keep this bookmarked for a handy botanical reference. You can use the “Control F” function in your browser to search for a specific term.  Otherwise it is in alphabetical order and you can use the table of contents or scroll through to find the term you are looking for.  Please Contact Me if you have any terms that you think are missing and should be added to my collection.  

A

• ~ is used to denote approximately, or synonymous with (families, genus, species). 
• ab- A prefix meaning “from, away from, or outside”.
• abaxial – The surface of an organ facing away from the organ’s axis, e.g. the lower surface of a lateral organ such as a leaf or petal. Contrast adaxial.
• abiotic – abiotic factors or components are non-living factors that impact an ecosystem such as the soil type, slope, altitude, moisture level etc. Abiotic factors are part of the ecosystem and can impact the associated living things, but they are not living.
• abort – To abandon development of a structure or organ.
• abscission -The shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf.
• abscission zone – A specialized layer of tissue that allows an organ to be shed by abscission when it is ripe or senescent. Such tissue is commonly formed, for example, at the base of a petiole or pedicel.
• acaulescent – Having no apparent stem, or at least none visible above the ground surface. Examples include some species of Agave, Oxalis… Antonym of caulescent (possessing stem)
• accessory Fruit – a fruit in which some of the flesh is derived not from the floral ovary but from some adjacent tissue exterior to the carpel.  Parts included are calyx, hypanthium, perianth and receptacle.  Eg include Strawberries (pseudocarp) and Apples (pomes).
• accrescent – Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen, e.g. in Physalis peruviana.
• accumbent – Lying against another part of the plant; when applied to a cotyledon, it means that one edge of the cotyledon lies along the radicle.
• achene – A dry, one-seeded indehiscent fruit.  Some achenes can also be found in aggregate and accessory fruits (example achenectum and pseudocarps). 
• achenecetum – An aggregation of achenes, as in Ranunculus.
• achlamydeous – Flowers lacking perianth, with no sepals, petals or tepals.
• acicular – Slender or needle-shaped.
• acrocidal capsule – One that dehisces through terminal slits, or fissures, as in Staphylea.
• acropetal – adj: acropetally Moving from roots to leaves, e.g. of molecular signals in plants.
• acrophyll – The regular leaves of a mature plant, produced above the base, opp to bathyphyll.
• acrosarcum – Seeds embedded in fleshy pulp without distinct endocarp as in the Cactaceae; with persistent accessory calyx. 
• acrostichoid – (describing a type of sorus) Covering the entire abaxial surface of a frond, usually densely so, as in Elaphoglossum and Acrostichum.
• actino– A prefix that indicates a radial pattern, form, or morphology.
• actinocytic – star-celled – stomata with guard cells that are surrounded by at least five radiating cells forming a star-like circle
• actinodromous – (leaf venation) Palmate or radially arranged venation with three or more primary veins arising at or near the base of the leaf and either reaching the margin or not.
• actinomorphic – Regular or radially symmetrical; may be bisected into similar halves in at least two planes. Applies e.g. to steles and flowers in which the perianth segments within each whorl are alike in size and shape. Compare regular; contrast asymmetrical, irregular, zygomorphic.
• actinomycetes – A group of gram-positive bacteria (order Actinomycetales) that produce various bio-active agents including antibiotics, enzymes, and vitamins. 
• aculeate – Armed with prickles, e.g. the stem of a rose.
• accuminate – Tapering gradually to a point. Contrast acute and mucronate.
• acute – 1.  Sharply pointed, but not drawn out. Contrast accuminate.  2.  Converging at an angle of less than 90°. Contrast obtuse.
• acyclic – Flowers, arranged in spirals instead of whorls (eg Magnolia). Compare cyclic.
• ad– A prefix meaning “near or towards”; also meaning “added to”.
• adaxial – The surface of an organ facing towards the organ’s axis, e.g. the upper surface of a lateral organ such as a leaf or petal. Contrast abaxial.
• adelphia, plural: adelphiae – a bundle or structure of stamens forming one unit in an adelphous flower; for example, the stamen tube around the pistil of Hibiscus.
• Adelphous – Having organs, particularly filaments such as stamens, connected into one or more adelphiae, whether in the form of bunches or tubes, such as is commonly seen in families such as Malvaceae. Usage of the term is not consistent; some authors include closely bunched filaments, while others include only adelphiae in which filaments are connected at their bases at least. See for example, Sims: “…the filaments are so closely pressed that they have the appearance of being monadelphous…”.[2] Compare derived terms such as monadelphous, having stamens growing in a single bunch or tube, for example in Hibiscus, and diadelphous growing in two bunches.
• adherent – Slightly united to an organ of another kind, usually to a part of another whorl, e.g. a sepal connected to a petal. Contrast adnate.
• adnate – Adj: adnation. Grown from or closely fused to an organ of a different kind, especially along a margin, e.g. a stamen fused to a petal. Adnate anthers have their halves attached to the filament through most of their length. (Contrast connate.)
• adpressed – Lying close and flat and pointing toward the apex of the plant or structure, usually referring to leaves growing up against the stem (= “appressed”). adventitious. A structure such as a bud or root that is produced on an unusual part of the plant (i.e., roots that come from stems).
• adventitious – Produced in an unpredictable or unusual position, e.g. an adventitious bud produced from a stem rather than from the axil of a leaf. Adventitious roots may develop from nodes of prostrate stems of some plant species, or from the hypocotyl rather than from the radicle of a germinating monocotyledon.
• adventive – Introduced accidentally (usually referring to a weed).
• aerenchymatous –A soft plant tissue containing air spaces, found especially in many aquatic plants. Oxygen transport from above-ground parts to roots of wetland plants is facilitated by aerenchyma.
• aerial – Of the air; growing or borne above the surface of the ground or water.
• aestivation – Arrangement of sepals & petals or their lobes in an unexpanded bud. Contrast vernation.
• aff. (affinis) – With affinity to others, akin to; often used for a provisionally recognized but unnamed taxon considered close to that name, perhaps a hybrid or extreme variant.
• agglutinate – firmly stuck together in a stiff mass
• aggregate fruit – A cluster of fruits formed from the free carpels of a single flower, e.g. Rubus. A fruit that develops from the merger of several ovaries that were separated in a single flower. Compare multiple fruits.
• alate – Having a wing or wings.
• aleurone –  is a protein found in protein granules of maturing seeds and tubers. The term also describes one of the two major cell types of the endosperm, the aleurone layer. The aleurone layer is the outermost layer of the endosperm, followed by the inner starchy endosperm.
• alkaloid – Any of a loosely defined class of organic compounds found in the tissues of many species of plants. Alkaloid molecules have one or more alkaline-reacting nitrogen atoms in their carbon structures. Many alkaloids are commercially important as drugs or poisons, e.g. caffeine, morphine, quinine, and strychnine, each of which occurs naturally in certain plants.
• alternate – 1.  (adj.) (of leaves or flowers) Born singly at different levels along a stem, including spiraled parts. Contrast opposite. 2.  (prep.) Occurring between something else, e.g. stamens alternating with petals.
• alterniperianth – adjective. Especially of a stamen positioned between the perianth divisions, used with flowers that have tepals instead of sepals and petals. 
• alternipetalous – adjective. Especially of a stamen positioned between the petals or divisions of the corolla.
• alternisepalous – adjective. Especially of a stamen positioned between the sepals or divisions of the calyx.
• alveolate – Having generally uniform, regularly and closely disposed, transversely polygonal depressions overall, the pattern resembling the external aspect of a honeycomb.
• ament – A synonym of catkin.
• amoeboid tapetum – a tapetum that breaks down early and the contents of the cell (protoplasm) extrude between the young pollen grains providing a more efficient way of nourishing them. 
• amphisarcum – A simple, indehiscent fruit with the pericarp differentiated externally into a dry crust and internally into one or more fleshy layers. Eg Crescentia alata.
• amphipacific – the divided (separated) distribution of aquatic organisms of various subspecies or similar species in the northern half of the Pacific Ocean.
• amphitropous – When the ovule is bent so that both ends are near each other. Contrast anatropous, campylotropous, and orthotropous.
• amplexicaul – With the base dilated and clasping the stem, usually of leaves.
• amylum  star – a vegetative propagative body filled with starch (amylum) and located around the lower nodes of certain stoneworts.
• anastomose – Branching and then rejoining, as with leaf venation.
• anastomosis – A connection or fusion of two or more veins that are normally diverging or branching, thereby forming a network.
• anatropous – (of an ovule) Inverted so that the micropyle faces the placenta (this is the most common ovule orientation in flowering plants). Contrast amphitropous, campylotropous, and orthotropous.
• androdioecious – Having bisexual flowers and male flowers on separate individuals. Contrast andromonoecious, polygamodioecious, polygamomonoecious, and polygamous.
• androecium – A collective name for the male reproductive parts of a flower; the stamens of a flower considered collectively. Contrast gynoecium. Abbreviated A; (A 3+3 indicates six stamens in two whorls)
• androgynophore – A stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth, formed from growth of receptacle.
• androgynous – Having male and female flowers in the same inflorescence.
• androphore – The stalk or column supporting the stamens in certain flowers, formed from growth of receptacle or more often from fusion of filaments eg Malvaceae.
• andromonoecious – Having bisexual flowers and male flowers on the same individual plant.
• andromedotoxin  – a toxic compound C31H50O10 found in various plants (as members of the genus Andromeda) of the heath family (Ericaceae) that lowers the blood pressure of animals when taken in small doses. Contrast androdioecious, gynomonoecious, polygamodioecious, polygamomonoecious, and polygamous.
• anemophilous – Adapted to pollination by wind.
• anemophily – Adaptation to pollination by wind.
• anisocytic – unequal celled, guard cells between 2 large subsidiaries and 1 smaller one.
• anisomerous or anisomery – The condition of having a floral whorl with a different (usually smaller) number of parts from the other floral whorls.
• anisophyllous – having leaves of two or more shapes and sizes. Contrast isophyllous. 
• anisotomic – Branching, with branches having unequal diameters (ie trunk and branch) Contrast isotomic.
• anomalicidal or Irregular Dehiscent Capsule – One that dehisces irregularly, as in Ammannia.
• anomocytic – irregularly celled stomata
• annulus – 1.  A ring-like structure. Pappus bristles are sometimes attached to a ring called an annulus or disk at the top of the achene beak. In some pollen grains, the exine around the apertures is either thicker or thinner. In pores, this border is termed an annulus. Certain flowers have ring-like constrictions at the mouth of the flower (Huernia, Aristolochia). 2.  A ring of specialized cells on the sporangium.
• anterior – Positioned in front of, towards the apex. Compare distal.
• anthemoid – In Asteraceae, a style with a brush-like tuft of sweeping hairs at the tip of each style branch.
• anther – The pollen-bearing part of a stamen.
• antherode – A sterile anther of a staminode.
• anthecium – Fruit derived from spikelet with only 1 floret, disarticulation always above glumes
• anthela – a cymose corymb with the lateral flowers higher than the central ones.
• anthesis – 1.  (of a flower) The period during which pollen is presented and/or the stigma is receptive. 2.  (of a flowering plant) The period during which flowers in anthesis are present. Not defined for some cases, such as when pollen is released in the bud.
• anthocarp – A type of fruit in which part of the flower persists attached to the pericarp (ie Nyctaginaceae)
• anthocyanin adj: anthocyanic – red, violet or blue pigment found in certain plants and flowers. While this pigment is mainly found in higher plant’s fruits and flowers, it can also be found sometimes in the plant’s roots, stems and leaves
• anthophore – A stalk-like structure located between the calyx and the other parts of the flower, produced by elongation of the internode between the calyx and the corolla, it supports the corolla, androecium and gynoecium.
• anticlinal – Pointing up, away from, or perpendicular to a surface. Contrast periclinal.
• antipetalous – Used of inner parts of flowers, most often stamens, that are in equal number to and aligned with the petals. Also spelled antepetalous. 
• antrorse – Directed towards or upwards, e.g. of hairs on a stem. Contrast retrorse.
• anxiolytic – a medicine used to prevent or reduce anxiety; herbal anxiolytics are much less habit-forming than the pharmaceutical alternatives.
• apetalous – Lacking petals.
• apex – pl. apices – The tip; the point furthest from the point of attachment.
• aphananthous – (of flowers) Inconspicuous or not showy, as opposed to phaneranthous or showy.
• aphlebia – pl. aphlebiae – Imperfect or irregular leaf endings commonly found on ferns and fossils of ferns from the Carboniferous Period.
• aphyllous – naturally leafless plants, aka switch plants with their photosynthetic functions transferred from leaves to green photosynthetic stems (eg: Cacti).
• apical – adj. apiculate. At or on the apex of a structure, usually a shoot, a stem, or the trunk of a tree, e.g. an apical meristem or an apical bud. In placentation where one or few ovules attach to the top of a simple or compound ovary. 
• apicifixed – anthers attached to the filament at the top and pointing back toward the filament like a hook.
• apiculus – the short pointed bud of a spore
• apiphily – A form of pollination whereby pollen is distributed by honey bees.
• apo– A prefix meaning “away from, separate, without”.
• apocarpous – Having separate carpels, not fused.
• apomixis – also apomixy, adj apomictic – A type of asexual reproduction whereby viable seeds or spores are produced asexually, without fertilization, such that the genetic material they contain is a clone of the parent’s genetic material. A plant produced in this way is called an apomict.
• apomorphy – In cladistics, a “different form” from the form of an ancestor (i.e., an innovation) of use in determining membership in a clade.
• apopetalous – Having separate petals, not fused (sympetalous).
• apophysis – 1.  The external part of a cone scale.  2.  An outgrowth of an organ or enlargement of a stem.
• apotropous – Ovules turned away from the placenta 
• appendage – A secondary part attached to a main structure; an external growth that seldom has any obvious function, hence appendiculate.
• appendiculate – Having the nature of or bearing appendages.
• appressed – Pressed closely but not fused, e.g. leaves against a stem, hairs on a leaf.
• arachnoid – Cobwebby, from being covered with entangled fine white hairs.
• arborescent – Tree-like in growth or general appearance.
• arbuscule – hyphal coils, the site of nutrient transfer between the fungus and plant roots in mycorrhiza. 
• archaeophyte – A non-native plant that has nonetheless been present in a particular geographic area for some time. Contrast neophyte.
• arctotoid – In the Compositae, a style with a ring of sweeping hairs borne on the shaft of the style proximal to the style branches.
• areolate – Having or being composed of areoles, as an areolate crustose lichen.
• areole – 1.  A space between the threads of a net, e.g. that part of a leaf surface defined by each of the elements of a vein network; as with cacti, the area between the veinlets of a leaf. 2.  A structure on the stem node of a cactus; the region of a cactus upon which spines and flowers are borne. 3.  In lichenology, a polygonal piece of a thallus surface where a crustose lichen is broken up like old dried and cracked paint, or like the polygonal “islands” of dried mud in a dry lake bed.
• aril – A membranous or fleshy appendage formed by expansion of the funicle which partly or wholly covers a seed, e.g. the fleshy outer layer of lychee fruit, or that found in members of the Sapindaceae.
• arista – adj: aristate – having a spiny or stiff bristle tip, as in the awns of some grasses
• articulated – jointed, the joints are usually where the plant will break apart easily.
• ascus or Pl asci – a saclike structure produced by Ascomycota fungi in which usually 4 or 8 sexually produced spores (ascospores) are formed.
• asperous – having a rough surface
• auriculate – Having two lobes, often curved near the base. ear-shaped parts or appendages. auricular.
• autogamous – capable of self-fertilization.
• autotroph – An organism capable of synthesizing its own food from inorganic substances using light or chemical energy. Green plants, algae, and certain bacteria are autotrophs
• axil – The upper angle between one part of a plant and another, e.g. the stem and a leaf.
• axile – On an axis; of a placenta, on the central axis of the ovary where the septa join the central placenta. 
• axillary – Born in or arising from the axil, usually referring to the axil of a leaf.
• axis – The main stem of a whole plant or inflorescence; the line along which this stem extends.

B

• baccate – bearing berries – berry like
• baccacetum – an aggregate of berries e.g. Actaea.
• baculiform – Rod-like; longer than wide. Compare cylindrical.
• balausta – a fleshy accessory fruit like the pomegranate, succulent within and many-seeded, with a firm rind, and tipped with the persistent lobes of the calyx.
• barb – A rear-facing point, as in a fish hook.
• barbed – Having barbs pointing in one direction.
• barbellate – Having barbed hairs (barbellae) down the sides.
• basal – Situated or attached at the base, as in placentation with ovules attached at base of ovary.
• basicidal capsule – One that dehisces through basal slits or fissures, as in some species of Aristolochia.
• basifixed – Something attached by its base, e.g. an anther attached to the filament. Compare dorsifixed.
• basipetal – Developing sequentially from the apex towards the base (i.e. with the youngest towards the base), e.g. of flowers in an inflorescence. Also, moving from leaves to roots ie molecular signals in plants.
• bathyphyll – A specialized leaf produced at the base of a plant, usually when the plant is immature, and which serves to anchor the plant to a substrate; especially notable in Teratophyllum of the Dryopteridaceae. Contrast acrophyll.
• beak – A prominent, pointed terminal projection, especially of a carpel or fruit.
• berberine – a quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids found plants like Berberis vulgaris (barberry), Berberis aristata (tree turmeric), Mahonia aquifolium (Oregon grape), Hydrastis canadensis (goldenseal), Xanthorhiza simplicissima (yellow root),
• berry – A type of indehiscent fruit from one ovary, without a stone pit, with the seeds immersed in the pulp, e.g. a tomato, bluebeberry.
• bi– A prefix meaning “two”; e.g. bisulcate, having two sulci or grooves.
• bidentate – having tooth-like projections that are themselves dentate again.
• bifacial – In leaves where the upper and lower surfaces are different
• bifid – Forked; cut in two for about half its length. Compare trifid.
• bifoliate – sometimes bifoliolate – of a compound leaf having precisely two leaflets, usually in a symmetrical pair, e.g. leaf of Colophospermum mopane. Compare jugate lobed leaf, e.g. most Bauhinia spp.
• bifurcate – bifurcated – to divide or fork into 2 branches
• bifusiform – Fusiform with a pinch in the middle.
• bilabiate – Having two lips, e.g. the form of the petals in many irregular flowers.
• bilateral – 1.  Having two distinguishable sides, such as the two faces of a dorsiventral leaf. 2.  Arranged on opposite sides, e.g. leaves on a stem; cf. distichous and opposite. 3.  Bilaterally symmetrical, as in a leaf with a symmetrical outline.
• biloculate – Having two loculi, e.g. in anthers or ovaries.
• biome – a large area characterized by its vegetation, soil, climate, and wildlife.
• biotic –  living or once living components of a community, organisms, such like plants, fungi,  animals etc. Biotic may refer to life, the condition of living organisms or biotic material derived from living organisms, in ecology it is the sum of living/organic components of an ecosystem. 
• bipinnate – Doubly pinnate; e.g. a compound leaf with individual leaflets pinnately divided.
• bipinnatisect – A pinnatisect leaf with deeply dissected segments.
• bitegmic – (of an ovule) Covered by two integuments. Contrast unitegmic.
• biternate – leaf compound with division in two, Ternate, with each division divided into three.
• bivalve – adj. bivalvate. Having two valves or hinged parts. Contrast trivalve.
• blade – The lamina or flattened part of a leaf, excluding the stalk or petiole.
• bloom – A fine white or bluish waxy powder occurring on stems, leaves, and fruits. Easily rubbed off. 
• bole – The trunk of a tree, usually the portion below the lowest branch. Compare canopy.
• boreal – A forest that grows in regions of the northern hemisphere with cold temperatures. Made up mostly of cold tolerant coniferous species such as spruce and fir. 
• bostrychoid – Arranged on a conical surface (like a snail shell); used to describe inflorescences in which the buds are arranged in an almost helical manner on the outside of a long, tapering, conical rachis.
• botryoid – a raceme with a terminal flower, often improperly called a raceme but it is a determinant inflorescence not indeterminate.  
• brachiate – having widely diverging branches, bibrachiate is with 2 wide diverging branches. 
• bract – A modified leaf associated with a flower or inflorescence and differing in shape, size, or colour from other leaves (and without an axillary bud).
• bracteate – Possessing bracts.
• bracteole – A small bract borne singly or in pairs on the pedicel or calyx; synonymous with bractlet.
• bracteolate – Possessing bracteoles (bractlets).
• bractlet – See bracteole.
• branchlet – A small branch.
• brevideciduous – A plant that loses all of its leaves only briefly before growing new ones, so that it is leafless for only a short time, e.g. approximately two weeks.
• bristle – adj. bristly. A straight, stiff hair (smooth or with minute teeth); the upper part of an awn (when the latter is bent and has a lower, stouter, usually twisted part, called the column).
• brochidodromous – Pinnate leaf venation in which the secondary veins do not terminate at the leaf margin, but are joined in a succession of prominent arcs.
• brochus – pl. brochi – Width of one lumen of a pollen grain reticulum and half of the width of the surrounding muri (walls), hence heterobrochate and homobrochate, where the lumina are of different or similar sizes, respectively.
• bulb – adj: bulbaceous A thick storage organ, usually underground, consisting of a stem and leaf bases (inner ones fleshy).
• bulbel – A bulb arising from another bulb. See bulblet.
• bulbil – A small, deciduous bulb or tuber formed in the axil of a leaf or pinna; vegetative propagation.
• bulblet – Pl. bulbets. A bulb arising from another bulb; a bulbel.
• bullate – Having rounded or globular blisters on the surface.
• bur / burr – 1.  A prickly fruit.  2.  A rough or prickly propagule consisting of a seed or fruit and associated accessory floral parts (usually bracts).
• buttress root – A root growing from an above-ground stem or trunk, and providing support, e.g. commonly of Ficus macrophylla.
• byssoid – A growth form of a lichen thallus that is wispy, like teased wool.

C

• C – In lichenology, “C” is an abbreviation for the test result of placing 5% solution of calcium hypochlorite or sodium hypochlorite (e.g. household bleach without additives) on the cortex or medulla of a lichen, to note the change in color, with no reaction noted as “C−”, and production of a bright colour noted as “C+”.
• caducous – Falling off early, e.g. the sepals of poppies, which fall off when the petals begin to open. compare persistent and fugacious.
• caespitose – Tufted or turf-like, e.g. the growth form of some grasses.
• calcarate – possessing a spur.
• calcareous – A soil type or a lichen substrate rock type that is rich in calcium carbonate.
• calceolate – a corolla that is shoe or slipper shaped, the labellum in many Orchids
• callose – Hardened; thickened; callous.
• callus – pl. calli – 1.  A protruding mass of tissue. 2.  Undifferentiated tissue growth formed in response to wounding; may be grown in vitro. 3.  In orchids, fleshy outgrowths from the labellum which can be variously shaped from papillae to plates. 4.  In grasses, a hardened extension from the base of a floret (formed from the rachilla joint and/or the base of the lemma) which may or may not elongate and is often covered in hairs or bristles.
• calybium – a  hard one-loculed dry fruit derived from an inferior ovary, as in Quercus; sometimes  a synonym of glans, but typically glans contains the persistent cupulate involucre that a claybium lacks. .
• calyciflorus – Having petals and stamens attached to the calyx.
• calycode – an ambiguous calyx – usually used only in the Santalaceae.  Perhaps sepaline-petaloid.
• calycophyll – A leaf-like structure formed from a sepal or calyx lobe which enlarges, usually many-fold, before or after anthesis, especially when most other sepals or calyx lobes retain their original size. More extreme than an accrescent calyx, calycophylls are found in Rubiaceae. Compare semaphyll and pterophyll.
• calyculate – Having an epicalyx.
• calyculus – 1.  A cup-shaped structure formed from bracts resembling an outer calyx. 2.  In some Asteraceae, a circle of bracts below the involucre. 
• calyptra – A hood or lid. See operculum.  calyptrate – with a hood or lid. Galeate is a synonym. 
• calyx – calyxes or calyces – Collective term for the sepals of one flower; the outer whorl of a flower. Compare corolla.
• calyx tube – A tube formed by the fusion of the sepals (calyx), at least at the base.
• camara – indehiscent dry fruit, pericarpium of one carpel, coriaceous, slightly fleshy or dry, seeds free (e.g. Fabaceae, Krameriaceae, Posidoniaceae, Sapindaceae).
• camaretum – apocarps more than one seeded, pericarp is free (e.g. Damasonium of Alismataceae, Uvaria of Annonaceae, Curatella of Dilleniaceae)
• camarium – schizocarp of cameras; mericarps of monocarps with seeds free of pericarp, indehiscent or tardily dehiscent (e.g. Malva of Malvaceae, Alectryon of Sapindaceae, Tribulus of Zygophyllaceae)
• cambium – A tissue layer that provides partially undifferentiated cells for plant growth.
• campanulate – Bell-shaped.
• campo rupestre – campo rupestre is used to characterize the montane vegetation of the Espinhaço Range in Brazil but recently has also been broadly applied to define high altitude fire-prone areas dominated by grasslands and rocky outcrops. In Spanish campo means rural or countryside and literally translated together campo rupestre means “rock field”.
• camptodromous – Pinnate venation in which the secondary veins curve toward the margins, in some cases becoming nearly parallel with them, and not reconnecting with other veins to form loops.
• campylodromous – a type of leaf venation in which a series of more or less equal primary veins originate from a common point at the base, arch upward, and reunite toward the apex; e.g., species of Aristolochia.
• campylotropous – When the ovule is oriented transversely (i.e. inverted with its axis at right angles to its stalk) and with a curved embryo sac. Compare amphitropous, anatropous, and orthotropous.
• canaliculate – Channeled; having a longitudinal groove.
• canescent – Approaching white in color, as in a leaf covered with white down or wool, a synonym of hoary, sometimes used to denote greyish down instead of white.
• capillary – 1. A tube, pore or passage with a narrow, internal cross-section. 2. Slender; hair-like.
• capitate – 1.  (of an inflorescence) Having a knob-like head, with the flowers unstalked and aggregated into a dense cluster. 2.  (of a stigma) Like the head of a pin.
• capitulum – pl capitula. A dense cluster of sessile or subsessile flowers or florets, e.g. a flower head in the daisy family, Asteraceae. See pseudanthium.
• capsule – A dry fruit formed from two or more united carpels and dehiscing when ripe (usually by splitting into pieces or opening at summit by teeth or pores).
• carcerulus – A type of schizocarpic capsule (fruit) that breaks up on maturity into one-seeded segments or nutlets, as in the Lamiaceae, Malvaceae..
• carduoid – In the Asteraceae, having a style with a ring of sweeping hairs borne on the shaft of the style below the style branches.
• carina – See keel. Adj: carinate. 
• carinal canal – A longitudinal cavity in the stems of Equisetum and extinct Equisetopsida, coinciding with a ridge in the stem surface.
• carneous – Flesh-coloured, especially as applied to some flowers.
• carnose, carnous – Fleshy or pulpy in texture, especially as applied to some tissues or organs. Contrast coriaceous and corneous.
• carpel – The basic female reproductive organ in angiosperms, either consisting of a single sporophyll or a single locule of a compound ovary, with a style and a stigma. The gynoecium is the collective term for all of the carpels of a single flower.
• carpopodium – On achenes (Cypselas), an elongation of the base of the gynoecium which looks distinct; the abscission zone, where the achene is separated from the receptacle.
• cartilaginous – Hard and tough; gristly. Compare corneous and coriaceous.
• caruncle – A small piece of flesh-like tissue, typically lumpy or warty, growing on the testa near the hilum. Contrast aril. Adj: carunculate. 
• caryophyllus – resembling Pink family Caryophyllaceae – 5 petals all spreading outwards
• caryopsis – A dry, indehiscent, one-seeded fruit in which the seed coat is adnate to the fruit wall, derived from a one-loculed superior ovary, e.g. in most grasses.
• casparian strip – A continuous band of suberin in the radial primary cell walls of the endodermis in vascular plant stems and roots that forms a permeability barrier to the passive diffusion of external water and solutes into the vascular tissue.
• cassideous – Hood-, helmet- or bonnet-shaped; generally referring to floral anatomy, e.g. in the flowers of Aconitum, Satyrium, etc.
• cataphyll – Any plant structure which is morphologically a leaf but which has at most an incidental or transient photosynthetic function. They are either shed when their main function has been completed, or are incorporated into structures where, when dead, they serve a protective or supportive purpose.
• catenulate – In the shape of a chain; formed of parts or cells connected as if chained together, e.g. some diatoms, algae, and cyanobacteria such as Anabaena. See also concatenate.
• catkin – A spike, usually pendulous, in which the mostly small flowers are unisexual and without a conspicuous perianth, e.g. in willows, poplars, oaks, and casuarinas. The individual flowers often have scaly bracts and are generally wind-pollinated. Catkins shed as a unit.
• caudate – Having a narrow, tail-like appendage or tip, a drip tip. Contrast acuminate, cuspidate, mucronate.
• caudex – pl. caudices – The stem of a plant, especially a woody one; also used to mean a rootstock, or particularly a basal stem structure or storage organ from which new growth arises. Compare lignotuber.
• caudiciform – Stem-like or caudex-like; sometimes used to mean “pachycaul“, meaning “thick-stemmed”.
• caulescent – possessing a well-developed stem above ground, similar to cauline. Antonym of acaulescent (lacking an apparent stem)
• cauliflorous or cauline – leaves borne directly on aerial stem or caulis or usually referring to older stems when describing flowers or fruits born directly on the stem.
• cenanthous – (of a perianth) Lacking both stamens and pistil, i.e. with neither androecium nor gynoecium.
• cenobium – Separating nutlets which are dry,indehiscent (do not split at maturity) 4-parted fruits with a hard pericarp around a gynobasic style, as in the Boraginaceae and Lamiaceae.
• centrifixed – Of a two-branched organ attached by its center, e.g. a hair or anther.
• ceraceous – Having a waxy appearance, colour, or texture, e.g. flowers of many species of Ceropegia, and the waxy fruit of some species of Myrica.
• cernuous – Nodding, falling headlong or face down; inclined, stooping, or bowing forwards. Applied to many species with a nodding, stooping habit, such as many Narcissus and Dierama species. Many plant species bear the specific epithet “cernua”.
• cerrado – a vegetation type in tropical Brazil composed of savannas and grasslands amid humid and dry forests. In Spanish, cerrado means closed, thick or dense but in Brazil it describes an arid ecosystem with spp adapted to live with seasonal climate in the highlands of Central Brazil.  The second largest biome in South America after the Amazon. 
• cespitose – An alternative spelling of caespitose.
• chalaza – In plant ovules, the chalaza is located opposite the micropyle opening of the integuments. It is the tissue where the integuments and nucellus are joined.
• chartaceous – Having a papery texture.
• chamber – A cavity of an ovary.
• channeled – Sunken below the surface, resulting in a rounded channel.
• chasmogamous – Of flowers that are pollinated when the perianth is open. Compare cleistogamous.
• chasmophyte – A plant adapted to growing in crevices or hollows, cliff faces. Compare cremnophyte.
• chimera – An individual composed of two or more genetically distinct tissues, most commonly as a result of a graft and sometimes by mutations that occur during cell division or seed development.
• chiropterophilous – Pollinated by bats.
• chlorenchyma – Plant tissue consisting of parenchyma cells that contain chloroplasts and forming the basic green tissue of plant leaves and stems. 
• chlorophyllous – usually leaves, possessing chlorophyll.  Also achlorophyllous is without chlorophyll. 
• chlorosis – An abnormal lack or paleness of color in a normally green organ.
• ciliate – sing. cilium; pl. cilia adj. ciliated – Having very small hairs or hair-like protrusions more or less confined to the margins; ciliolate is minutely ciliate.   
• cincinni/cincinnus – a monochasium on which successive axes arise alternately in respect to the preceding one.  Syn: scorpioid cyme or boraginoid cincinni – borage like cincinni.
• circinate – Spirally coiled with the tip innermost, e.g. circinate vernation of developing fern fronds.
• circinotropous – The funicle in this case is especially long that it creates a nearly full circle around the ovule whose micropyle is ultimately pointing upwards.
• circumboreal – adj is a floristic region within the holarctic zone of Eurasia and North America, plants that inhabit the boreal zone at all longitudes. Compare with holarctic which despite the name extends further south covering all of Europe, most of Asia and almost all of North America. 
• circumscissile – capsules that open along a transverse circular line (circumferentially) as in Plantago. Note that Papaveraceae are also called circumscissile capsules but technically they are operculate capsules. Synonym pyxis. 
• cirrhous or cirrhose – a leaf ending in a tendril at the apex.
• cladode – A photosynthetic branch or stem, often leaf-like and usually with foliage leaves either absent or much reduced. Compare phyllode.
• cladodromous – with a single central vein from which secondary veins radiate on each side to the margins, pinnate with branching to the leaf margins.
• clathrate – Shaped like a net or lattice; pierced with apertures, as with a cage.
• clavate or claviform – Club-shaped.
• clavicipitaceous – endophytes (parasitic fungi) that grow within their plant host without manifesting symptoms of disease or harming their host.
• clavuncula – In the Apocynaceae, an enlarged, drum-shaped stigma of which the sides and lower surface are the receptive zones. Coherent with the anthers or not.
• claw – 1 Narrow stalk-like basal part of a petal, sepal or bract. 2 In Melaleuca united part of stamen bundle.
• cleft – a split or indentation up to half way down the center, eg petals. 
• cleistogamous – Having flowers which self-pollinate and never open fully, or which self-pollinate before opening. Compare chasmogamous.
• cline – adj clinal – A continuous morphological variation in form within a species or between two species.
• coalescent – Having plant parts fused or grown together to form a single unit.
• coccum – fruit opening along two sutures, unequal in length, often woody.  But not of the Fabales order (often Connaraceae, Myristicaceae, and Proteaceae).
• coccarium – mericarps of coccum monocarps in a schizocarpic fruit that open along 2 sutures eg: Euphorbiaceae, Hamamelidaceae, Zanthoxylum (Rutaceae), and others. 
• cochleariform – Concave and spoon-shaped.
• cochleate – Coiled like a snail’s shell.
• coenobium – An arranged colony of algae that acts like a single organism.
• coenocyte – A single cell with multiple nuclei, formed when nuclear division not followed by cytokinesis.
• coleoptile – One type of sheath in the structure of monocotyledonous seeds. The coleoptile is a protective sheath or cap (pileus), generally more or less pointed, that covers the monocotyledonous plumule as it emerges from the soil. It generally turns green and contributes to photosynthesis until its function is superseded by the main growth of the seedling. Contrast this with the coleorhiza, which remains underground until it is superseded as the roots emerge.
• coleorhiza – One type of sheath in the structure of monocotyledonous seeds. The coleorhiza connects the coleoptile to the radicle and protects the monocotyledonous radicle during germination. Unlike the coleoptile, the coleorhiza is associated with the root and does not emerge from the soil during germination. Contrast coleoptile.
• collenchyma – A specialized tissue consisting of living cells with unevenly thickened cellulose and pectin cell walls that performs a support function in organs such as leaves and young stems that are composed of primary plant tissues.
• colleter – A multicellular, glandular hair that usually produces a mucilaginous substance and is located on sepals, stipules, or petioles, or on nearby parts of stems; commonly found on plants of order Gentianales.
• colpi – Eudicots usually have three apertures that run from the proximal side of the pollen grain to the distal side named colpi and the pollen type of the Eudicots is called tricolpate.
• columella -In flowering plants, the central axis of the cone or fruit, e.g. in Callitris.
• column – 1.  A structure extending above the ovary and incorporating the style and stamens also known as the gynostegium, e.g. in orchids and milkweeds.  2.  In grasses, the lower, stouter, and usually twisted part of an awn, distinct from the slender upper part or bristle.
• columnar – Shaped like a column.
• coma – 1.  A tuft of hairs from testa or funiculus at one or both ends of some seeds, e.g. in Strophanthus, Asclepias, or Alstonia.  2.  Sterile bracts, e.g. in Curcuma, Ananas, or Eucomis.  3.  Sterile flowers, e.g. in Muscari and Leopoldia, at the apex of some inflorescences.  4.  A tuft of hairs at the base of some flowers, e.g. in Pfaffia gnaphalioides. 5.  A tuft of hairs at the apex or base of some spikelets.  6.  An axil tuft of hairs in inflorescences in some Poaceae, e.g. in Eragrostis comata.
• commelinids – Clade of monocots distinguished by cell walls containing ferulic acid.  
• commissure (commissural) – The seam or face at which two carpels adhere. See also fissure and suture
• comose – coma: the hair of the head. A tuft of hairs surrounding the terminal or basal tips of some fruits, seeds, leaf or branches. A coma arises from the seed or other part, while a pappus is a modified calyx.
• compound – Composed of several parts, e.g. a leaf composed of multiple leaflets, a gynoecium composed of multiple carpels, or an inflorescence made up of multiple smaller inflorescences.
• compound palmate – Having leaflets that radiate from a central point (usually at the top of a petiole), like spread-out fingers radiating from the palm of a hand. Compare palmate.
• compressed – Flattened lengthwise, either laterally (from side to side) or dorsally (from front to back).
• concatenate – Joined together in a chain-like form. See also: concatenate and catenate.
• concolorous – Having the same colour throughout; uniformly coloured.
• concrescent – the growing together of related parts, tissues or cells.  The union of cell walls by means of a concreting substance. 
• conduplicate – Arranged such that two sides of a flat surface are folded along the midline to face each other. See also ptyxis, aestivation, and vernation.
• cone – A type of fruit, usually woody, ovoid to globular, including scales, bracts, or bracteoles arranged around a central axis, e.g. in gymnosperms, especially conifers and Casuarina.
• conflorescence – A rarely used term describing substantial differences between the overall structure of an inflorescence and that of its individual branches, e.g. the bottlebrush multiple-flower head of members of the genus Callistemon.
• connate -Fused to another organ(s) of the same kind, e.g. petals in a corolla tube. Compare adnate.
• connective – The part of an anther that connects the anther cells.
• connivent – Coming into contact or converging, but not fused.  Syn: Cohering?
• conspecific – Belonging to the same species.
• contiguous – adjoining, touching, but not united.
• contort – (of sepals or petals) A type of imbricate aestivation in which one side of each segment overlaps one of the adjacent segments and the other side is overlapped by the other adjacent segment. See convolute.
• contorted – Twisted out of the normal shape; in aestivation with 1 side over its neighbor and the other side under its other neighbor.
• contortuplicate – in aestivation where it is both contorted (1 side each over and under its nearest neighbors) and plicate (folded lengthwise).
• convolute – 1.  Referring to the arrangement of floral or foliar organs in a bud when each organ or segment has one edge overlapping the adjacent organ or segment; a form of imbricate arrangement. See contort. 2.  (of leaves) A type of venation in which one leaf is rolled up inside another. 3. Type of vernation of two leaves at a node where one half of each leaf is exposed and the other half is wrapped inside the other leaf.
• corcle – A plant embryo, plumule, or plumule plus radicle.
• cordate – Heart-shaped, with the notch lowermost; of the base of a leaf, like the notched part of a heart. Contrast obcordate.
• coriaceous – Leathery; stiff and tough, but flexible. Compare corneous. Also subcoriaceous is almost leathery.
• corm – A fleshy, swollen stem base, usually underground and functioning in the storage of food reserves, with buds naked or covered by very thin scales; a type of rootstock. Adjectives derived from “corm” include “cormose” and “cormous”.
• corneous – Horny in texture; stiff and hard, but somewhat tough. Compare coriaceous.
• corolla – A collective term for the petals of a flower. Pertaining to corolla is corolline. Compare calyx.
• corona – adj: coronate 1.  In flowering plants, a ring of structures that may be united in a tube, arising from the corolla or perianth of a flower and standing between the perianth lobes and the stamens. The trumpet of a daffodil is a corona.  2.  In grasses, a hardened ring of tissue surmounting the lemma in some species.
• corpuscule also corpuscle – any minute particle.  Corpusculum  is a structure connecting the two translators of the pollinia of Apocynaceae subfamily Asclepiadoideae
• cortex – pl. cortexes or cortices – In lichens, the “skin” or outer layer of thallus tissue that covers the medulla. Fruticose lichens have one cortex encircling the branches, even flattened, leaf-like forms; foliose lichens have different upper and lower cortices; crustose, placodioid, and squamulose lichens have an upper cortex but no lower cortex; and leprose lichens lack any cortex.
• corticolous – Growing on bark or on wood with the bark stripped off. Compare lignicolous.
• corymb – adj corymbose An inflorescence with branches arising at different points but reaching about the same height, giving the flower cluster a flat-topped appearance.
• costa or costae (pl) or adj costate – A rib. Adj having veins or ridges, especially parallel ones.
• costapalmate – Having a definite costa (midrib), unlike the typical palmate or fan leaf, but with the leaflets arranged radially as in a palmate leaf.
• crassinucellate – Ovaries/ovules – with many parietal cells and a large nucleus.  
• craspedium –  a one-carpellate fruit splitting transversely into one-seeded segments; seed-bearing segments separate from each other and from the persistent replum (ie Mimosa). Sometimes incorrectly called a loment, but they are both schizocarps, but the craspedium leaves behind a persistent replum. 
• craspedodromous – Pinnate venation in which the secondary veins terminate at the margins, often as teeth. Simple is simple pinnate ending at the margins, semicraspedodromous is ;mixed craspedodromous is a mix of both craspedodromous and camptodromous. 
• crateriform – In the shape of a saucer or shallow cup; hemispherical or more shallow.
• cremnophyte – A plant adapted to growing on or hanging from cliffs or crevices. Compare chasmophyte.
• cremocarp – also called schizocarpic mericarps, or carpopodium. Separating mericarps which are dry, seed-like fruits derived from an inferior ovary, as in the Apiaceae.
• crenate – Having blunt or rounded teeth; scalloped.
• crenulate – Minutely scalloped.
• crispate – of a leaf having curly or wavy edges.
• crisped – Finely curled, as with the edges of leaves and petals.
• cristarque  cell – A sclereid which contains a druse and has the lignin deposited excentrically on the cell wall to form a cup shape, or in cross-section, a ∪-shape.
• cross venulation – Also cross-venules – leaf venation going horizontally across the leaf
• crozier – characteristic coiled inflorescence in Boraginaceae also used for Ascomycota fungi characteristic feature at the base of their asci that also look like a hook-topped shepherd’s staff.
• cruciform – Cross-shaped, as in 4 petaled flowers.
• crustaceous – Hard, thin and brittle.
• crustose – Forming a closely applied surface layer or crust.
• cryptocotylar – a type of seed germination in which the cotyledons remain within the seed coat at germination.
• cryptogam – Any of the “lower plants” which produce spores and do not have stamens, ovaries, or seeds; literally, plants whose sexual reproductive organs are not conspicuous. This group typically includes the ferns, bryophytes, and algae, and sometimes fungi (including lichenized fungi). Compare phanerogam.
• cucullate – also cucullus  Hood-like or hooded, commonly referring to the shape of leaves or petals, e.g. Pelargonium cucullatum. Similarly derived terms include cuculliform and cuccularis.
• culm – In grasses, sedges, rushes, and some other monocots, an aerial stem bearing the inflorescence, extending strictly from the base of the plant to the lowest involucral bract (or base of the inflorescence).
• cultigen – A plant whose origin or selection is primarily due to intentional human activity.
• cuneate – Wedge-shaped, with straight sides converging at a base.
• cupule – A cup-shaped structure composed of coalescent bracts, such as the cup of an acorn. See calybium.
• cupular – Shaped like a cupule.
• cupulate – Bearing cupules.
• cupuliform – Nearly hemispherical, shaped like a cupola or dome.
• cusp – A hard, pointed tip, stiffer and more formidable than a mucronate, hence cuspidate.
• cuspidate – Tipped with a cusp, as with some leaves.
• cuticle – A waterproofing layer covering the epidermis of aerial plant surfaces and composed of the polymers cutin, and/or cutan and waxes.
• cyanthiform – in the shape of a deep cup or saucer
• cyathium – pl. cyathia, adj cyathiform  – An inflorescence of unisexual flowers surrounded by involucral bracts, especially the flowers of Euphorbia.
• cyathophyll – in Euphorbia, the bract-like structure on which the involucre sits, usually but not always occurring in twos. They may sometimes be brightly colored and confused with petals.
• cyclic – Flowers, arranged in whorls.  Compare acyclic arranged in spirals (Magnolia)
• cyclocytic – Stoma surrounded by at least 4 cells arranged in a ring around the stoma
• cylindrical – rod-like and two to three times as long as wide. Compare baculiform.
• cyme – adj. Cymose – A type of inflorescence in which the main axis and all lateral branches end in a flower (each lateral may be repeatedly branched). A cymule is a small cyme. 
• cymose – Having a cyme or cymes.
• cypsela – A type of dry, one-seeded, indehiscent fruit formed from a one loculed inferior ovary with accessory hypanthium or calyx developing into terminal wings or bristles.
• cystoliths – is a botanical term for outgrowths of the epidermal cell wall, usually of calcium carbonate, formed in a cellulose matrix in special cells called lithocysts, generally in the leaf of plants. 

D

• deciduous – plants that tend to lose their leaves at maturity or annually in winter or dry seasons when they need to conserve energy.
• declinate – Curving downwards, and then upwards at the tip. Often qualified, e.g. declinate-ascendant.
• decompound – Divided to more than one level, e.g. in bipinnate leaves, in which the leaflets of what would otherwise be a pinnate leaf are themselves pinnately divided.
• decorticate – 1.  (intr. v.) To shed the outer bark of a tree, usually seasonally as part of the natural growth cycle. 2.  (tr. v.) To strip the peel, crust, bark, or other surface tissues from a plant or from harvested material, such as in extracting fibre from harvested Agave leaves.
• decumbent – Having branches growing horizontally along the ground but which are turned up at the ends.
• decurrent – Extending downwards beyond the point of insertion, e.g. when the base of a leaf or a fungal gill is prolonged downwards along the stem in a raised line or narrow wing.
• decussate – Opposite with successive pairs borne at right angles to the last; generally applied to the arrangement of leaves.
• dedoublement – where 2 or more structures are found but where only one is expected.
• definite – Of a constant number, e.g. twice as many stamens as petals or sepals (or less), or an inflorescence ending in a flower or an aborted floral bud, typically a cymose inflorescence. Contrast indefinite.
• deflexed – Bent downwards. Contrast inflexed.
• dehiscent – Breaking open at maturity to release contents; refers e.g. to the opening of fruits to release seeds, of anthers to release pollen, and of sporangia to release spores. Contrast indehiscent.
• deltoid – Shaped like the uppercase Greek letter Δ, i.e. like a more or less equilateral triangle.
• dendroid – adj: dendritic – Tree-like; branching like a tree.
• dentate – Toothed, especially in reference to leaf margins.
• denticidal – capsules dehiscing apically and leaving a ring of ‘teeth’ behind. Eg in Cerastium.
• denticulate – Finely toothed; a diminutive form of dentate.
• determinate – Limited, usually in growth. Contrast indeterminate.
• diacytic – Cross celled stomata guard cells surrounded by 2 subsidiary cells that each circle one end of the opening and contact each other opposite to the middle of the opening. 
• diadelphous – Referring to a class of adelphous structure in which the stamens or similar organs are connected in two adelphiae instead of just one.
• diaspore – Any reproductive part of a plant adapted for dispersal and for establishing new plants; may be a disseminule such as a seed, or other parts such as specialized buds, branches, inflorescences, or fruits.
• dichasium – pl: dichasia – A cymose inflorescence with all branches below the terminal flower in regular opposite pairs. Compare monochasium and pleiochasium.
• dichlamydeous – Having a perianth which is divided into a separate calyx and corolla. Compare homochlamydeous.
• dichotomous – symmetrically branching or forking into two equal branches. This may result from an equal division of the growing tip, or may be sympodial, in which the growing tip is aborted and replaced. Typically refers to mode of branch growth, as in Aloidendron dichotomum, but also to other organs, such as the venation patterns on leaves, the thorns of various species of Carissa (which morphologically are branches), and the thalli or hyphae of various algae and fungi.
• diclesium – Achene or nut surrounded by a persistent accessory calyx, as in Mirabali. 
• diclesarium.  Fruitlets of a schizocarp developing within an accrescent perianth 
• dicot – also dicotyledon have two cotyledons, or embryonic leaves, found in the seed embryo. Unlike monocots, dicots are not a monophyletic group and instead, a number of lineages diverged earlier than the monocots did. Dicots differ from monocots in six distinct structural features: the flowers (parts usually in 4’s or 5’s), leaves (usually palmate, pinnate or other vein, rarely parallel), roots (usually fibrous or tap roots, rarely with storage organs), stems (able to produce secondary growth, different vascularization), and pollen grains. However, the root of these differences stems from the very early embryonic stages of the angiosperm, providing the biggest difference of all between monocots and dicots: the seed.  Note that there  are always exceptions to the rule. Some of the early-diverging dicots seem to have typical monocot characteristics such as scattered vascular bundles, trimerous flowers, and monosulcate pollen grains and approximately 2% of angiosperms don’t fit into either category.  Early basal angiosperms and those that do not fit are typically classified in this book under the Basal Angiosperms. 
• didynamous – having four stamens disposed in pairs of unequal length —used especially of plants of the families Scrophulariaceae and Labiatae.
• digitate – digitately – With segments spreading from a common center, like the fingers of a hand. See also palmate and palmatisect.
• dimorphic – also: dimorphous – Occurring in two different forms (with respect to shape and/or size), e.g. of stamens, fronds, or leaves. See also monomorphic (having a single form) and polymorphic (having many forms).
• dioecious – (of vascular plants) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast monoecious.
• dioicous – (of a bryophyte gametophyte) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast monoicous.
• diplostemonous – Having stamens arranged in two whorls, with the outer whorl alternating with the petals while the inner whorl is opposite the petals. Compare obdiplostemonous and haplostemonous.
• diplotegium – A fruit, a pyxis derived from an inferior ovary.
• disc – Also spelled disk. A plate or ring of structures derived from the receptacle, and occurring between whorls of floral parts. In some groups, especially Sapindales, the nectary is in the form of a prominent disk. In daisies, the central part of the capitulum is a disk so flowers born there are called disk flowers or florets.
• discoid – Resembling a disc or plate, having both thickness and parallel faces and with a rounded margin. Also used to describe the flower head of Asteraceae where there are no ray florets but only disc florets.
• discolorous – (of leaves) Having upper and lower surfaces of different colours.
• disjunct – Occurring in widely separated geographic areas, distinctly separate; applies to a discontinuous range in which one or more populations are separated from other potentially interbreeding populations with sufficient distance so as to preclude gene flow between them.
• disk floret – A floret occurring most typically in the disk of the capitulum of flowers in the family Asteraceae, and to some extent in other plants that bear a flowering head with a disk, such as Scabiosa.
• dissected – Deeply divided; cut into many segments.
• dissepiment – A partition or septum in a plant part, usually referring to septa between the loculi of capsules or of other fruits with multiple partitions.
• distal– Remote from the point of origin or attachment; the free end. Contrast proximal.
• distichous – Arranged in two opposite rows (and hence in the same plane); aka two-ranked. 
• distinct – Separate or free; not united.
• distyly – Adj: distylous. The condition in which the flowers of a species occur in two forms that differ only by the length of the style and stamens, flowers of only one of these forms appear on any one plant. Compare heterostyly.
• dithecal – . having two thecae or receptacles.
• divaricate – Wide-spreading.  Adj: divaricately 
• divergent – Spreading in different directions, generally upward.
• domatia – sing. domatium – Any hollow structure formed by a plant that is inhabited by ants or mites.
• dorsal – From Latin dorsum, a ridge or the back of an animal. Partly because the term originally referred to animals rather than plants, usage in botany is arbitrary according to context and source. In general “dorsal” refers to “the rear or back or upper surface”, but in botanical usage such concepts are not always clearly defined and may be contradictory. For example: facing away from the axis (abaxial) in a lateral organ of an erect plant. Related anatomical terms of location include ventral, lateral.
• dorsifixed – Attached at or by the back, e.g. anthers on a filament.
• dorsiventral – Having structurally and visibly different upper and lower surfaces, e.g. some leaves.  Dorsiventral leaves orient themselves at an angle to the main axis and perpendicular to the direction of sunlight. Most dicots have dorsiventral leaves.  Compare bilateral and isobilateral.
• double cyme – with a complete cyme branching off each side of the main axis. 
• drip tip – A long, narrow, acuminate, caudate, or cuspidate extension at the tip of a leaf or leaflet. Commonly an adaptation to rainy conditions, as it promotes shedding of water by its dripping from the narrow tip. The term “drip tip” is not anatomically descriptive in the way that say, acuminate or cuspidate, are; rather it is a description of the functional shape that aids dripping, irrespective of the specific geometry of the shape itself.
• drupe – A type of succulent fruit formed from one carpel; the single seed (pyrene) is enclosed by a stony layer of the fruit wall, e.g. in peaches and olives. 
• drupecetum – An aggregation of drupelets, as in Rubus.
• drupelet – A small drupe formed from one of the carpels in an apocarpous flower. Drupelets usually form a compound fruit, as in Rubus, but they may become widely separated, as in Ochna.
• druse – A globular mass of calcium oxalate crystals, usually the crystals radiating from an organic core.

E

• ebracteate – Lacking bracts; synonymous with ebracteolate.
• echinate –  Bearing or covered with spines or bristles; prickly. or adj biology covered with spines, …
• ecological amplitude – The range of environmental conditions in which an organism can survive.
• ectomycorrhizal – Fungi that do not penetrate the root cell walls and instead form an inter-cellular interface (Hartig net) made of a lattice of hyphae between the epidermal and cortical root cells. 
• ectoparasite – adj: ectoparasitic. A parasite, such as a flea, that lives on the outside of its host. Compare with endoparasite.
• edaphic – Of or influenced by the soil. 
• elaiosome – An external structure attached to the seed of many species of plants. Elaiosomes generally look fleshy and in some species they are rich in oils or other nutritious materials. Their functions vary and are not always obvious; commonly they attract ants or other animals that aid in dispersal, but they may also repel other animals from eating the seed.
• elephophily – A form of pollination whereby pollen or spores are distributed by the feet of elephants, as in Rafflesia arnoldii.
• elaminate – without leaf blades
• elater – a cell (or structure attached to a cell) that is hygroscopic and changes shape in response to changes in moisture. Elaters come in many forms but are always associated with plant spores.
• elfin – Elfin forest or stunted forest is a short gnarled forest of generally 1 -10 m height. The trunks, branches and forest floor are covered in moss, lichens, orchids and epiphyte plants. 
• ellipsoid – A three-dimensional shape that is elliptical in all sections through the long axis.
• elliptical – Also elliptic. – Planar, shaped like a flattened circle, symmetrical about both the long and the short axis, tapering equally both to the tip and the base; oval.
• emarginate – Notched at the apex (notch usually broad and shallow).
• embryo – The young plant contained by a seed prior to germination.
• embryogeny – the formation and growth of an embryo. Adj: embryogenic, embryogenetic.
• emergent – A plant taller than the surrounding vegetation or, among aquatic plant species, one that bears flowers and commonly leaves above the surface of the water. Aquatic examples include water lilies, reeds, and papyrus. Some pondweeds such as Stuckenia are not emergent until they flower, at which time only their flowers appear above the water surface.
• emerse – risen or standing out of water, surrounding leaves, etc.
• enantiostyly – the condition in which the gynoecium protrudes laterally, to the right (dextrostyly) or to the left (sinistrostyly) of the androecium, e.g. Senna.
• enation – an outgrowth from the plant surface of epidermal and subdermal tissue but not vascularized (but may have microphylls) 
• endocarp – The innermost layer of the wall of a fruit; in a drupe, the stony layer surrounding the seed.
• endodermis – The innermost layer of the cortex of vascular plant roots, also in the stems of pteridophytes. The radial walls are impregnated with suberin to form a permeability barrier known as the Casparian strip.
• endogenous – arising from within
• endomycorrhizal – Fungi that penetrate the cortical cells of the root and forms arbuscules and vesicles. 
• endophloic – Also endophloeodal. (of crustose lichens) Having the thallus growing within rather than upon the bark of trees. Compare epiphloedal and corticolous (growing on the surface of wood or bark) and endolithic (growing within rock).
• endoparasite –  A parasite that lives within the body of the host. 
• endophyte – pl endophytes – is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease; ubiquitous in plants. 
• endosperm – 1.  (angiosperms) A nutritive tissue surrounding the embryo of the seed, usually triploid, originating from the fusion of both polar nuclei with one gamete after the fertilization of the egg. 2.  (gymnosperms) The prothallus within the embryo sac.
• endospory – The production of spores that germinate into a reduced multicellular gametophyte contained within the spore wall. Contrast exospory.
• endozoochorous – Seed dispersal via ingestion by vertebrates (mostly birds and mammals), also endozoochory which is the dispersal mechanism for most tree species. Results from coevolution from a mutualistic relationship in which a plant surrounds seeds with an edible, nutritious fruit as a good food for animals that consume it.
• endosymbiont – a type of symbiosis in which one organism lives inside the other, the two typically behaving as a single organism.
• ensiform – Shaped like the blade of a sword.
• entire – 1. Not divided.  2. (of a margin) Smooth, not lobed or toothed (but possibly wavy or scalloped).
• entomophily – A form of pollination whereby pollen or spores are distributed by insects.
• epicalyx – An involucre resembling an outer calyx, e.g. as in Hibiscus.
• epicarp – the outer layer of the wall of a fruit, i.e. the “skin”.
• epicormic – Used to refer to buds, shoots, or flowers developing from the old wood of trees, especially after injury or fire.
• epicotyl – The part of the plant axis or stem between the cotyledonary node and the first foliage leaves.
• epicuticular wax – A layer of crystalline or amorphous wax deposited on the surface of the cuticle.
• epidermis – An organ’s outermost layer of cells, usually only one cell thick.
• epigeal – germination where cotyledons emerge above the surface after germination.
• epigynous – Borne on the ovary; describes floral parts when attached above the level of the ovary and arising from tissue fused to the ovary wall. Compare hypogynous and perigynous.
• epilithic – Growing on stone. Compare lithophytic, a plant growing on stone.
• epimatium – specialized ovuliferous scale that bears and encloses a single inverted ovule.  Found in Araucaria araucana and certain Podocarpaceae
• epinecral – Dead (necral) tissue above the surface of the cortex of a lichen.
• epipetalous – Of stamens that are attached to the petals.
• epipetric – Growing on rock or stone, lithophytic, epilithic.
• epiphloedal – Growing on the surface of bark. Contrast endophloedal (growing inside, not on, the bark) and epilithic (growing on rock, not bark).
• epiphyllous – Growing on the surface of a leaf, especially the upper surface, as in flowers
• epiphyte – A plant, alga or fungus that grows on another plant without deriving nourishment from it but using it for support.
• epiphytic – Of an epiphyte; living on the surface of a plant. Compare epilithic, lithophytic.
• epitepalous – Of stamens that are attached to the tepals.
• epitropous – ovules turned towards placenta, reverse of apotropous.  Synonym of anatropous???
• epizoochory – A type of seed dispersal that occurs when seeds or fruits physically adhere to the outside of vertebrate animal bodies.
• epruinose – Not pruinose.
• epulvinate – without a pulvinus – without a swelling at the base
• equitant – (of a leaf) Folded lengthwise and clasping another leaf.
• erect – Upright, more or less perpendicular to the ground or point of attachment. Compare patent (spreading) and erecto-patent, between erect and patent.
• ericoid – Having leaves like those of the European heaths (Erica); small and sharply pointed.
• erose – (of a margin) Irregular as though nibbled or worn away.
• ethereal – A plant product, usually somewhat volatile, giving the odors and tastes characteristic of the particular plant; usually, the steam distillates of plants or of oils obtained by pressing the rinds of plants. See also: volatile oil.
• even-pinnate – Having an even number of leaflets in a compound leaf; synonymous with paripinnate.
• ex – In nomenclature, indicating that the preceding author proposed the name but did not legitimately publish it, and that the succeeding author referred to the first author when legitimately publishing the name. 
• exalbuminous – In seeds having no endosperm, i.e. no albumen, e.g. in Fabaceae and Combretaceae.
• excentric – Off center, to one side
• exocarp – The outer layer of the pericarp, often the skin of fleshy fruits.
• exospory – Production of spores that germinate free-living multicellular gametophytes. Contrast endospory
• exotegmic – Pertaining to the outer portion of the integument.
• exotesta – The outer layer of the testa (seed coat). It is derived from the outer integument of the ovule.
• exserted – Projected beyond, e.g. stamens beyond the corolla tube. Also exsert. 
• exstipulate – Lacking stipules.
• extinction – the loss or dying out of a species due to environmental forces or evolutionary changes. The species ceases to exist.
• extirpation – the local extinction of a species in an area, though that species still continues to exist elsewhere.
• extrastaminal – Outside the stamens or androecium, usually referring to the location of a nectary disk.
• extrorse – (of anther locules) Opening towards the outside of the flower. Contrast introrse and latrorse.
• evergreen – plants that do not lose their leaves during the growing season and retain them into the following year.

F

• F1 hybrid – A single cross; a plant breeding term for the result of a repeatable cross between two pure lines. 
• F2 hybrid – A plant breeding term for the result of a plant arising from a cross between two F1 hybrids; may also refer to self-pollination in a population of F1 hybrids.
• fabiform – Shaped like a kidney bean.  Synonym of or similar to reniform?
• facultative – Of parasites, optional. Compare obligate.
• falcate – Curved like the blade of a scythe.
• farina – powdery, pale yellow crystalline secretion consisting of flavonoids in Primula and other species
• farinose – also farinaceous.  A powder coating that is mealy.
• fascicle – adj fasciculate – A cluster, e.g. a tuft of leaves, stamens, flowers etc all arising from the same node. In stamens usually branching from a single primorida.
• fasciculate – Branching in clusters like a bundle of sticks or needles; having fascicles.
• fastigiate – shrub or tree having branches sloping upwards erect and more or less parallel to the main stem. Erect and parallel. 
• faveolate – Honeycombed; having regular, angled pits. Compare foveolate.
• faucal – Pertaining to the fauces; located in the throat of a calyx or corolla.
• fauces – The throat of a calyx or corolla; the conspicuously widened portion between the mouth and the apex of the tube. In Boraginaceae, the site of distinctive appendages.
• felted – Covered with very dense, interlocked and matted hairs with the appearance of felt or woolen cloth.
• fenestrate – Having holes or large translucent areas. Compare punctate with small translucent patches.
• ferruginous – Ruddy or rust-colored.
• fiber – 1.  A fiber cell. .  Any flexible, strong, stringy, and very elongate structure.
• fiber  cell – a type of cell that is found in sclerenchyma, it is much elongated and dies soon after an extensive modification of its cell wall. The cell wall is usually thickly lignified, sometimes gelatinous.
• fibrous root – not a taproot, usually formed by thin, moderately branching roots growing from the stem, found in all monocots and many dicots.
• filament – 1.The stalk of a stamen.  2. any very narrow, thread-like structure that is one or a few cells thick.
• filamentous – consisting of filaments or fibres, hairlike.
• filantherous – typical stamen with distinct filaments and anthers, and without appendages. 
• filiform – thread-like. e.g. stamen filaments, or leaf shapes. Often misspelled filliform. 
• fimbria – slender hair-like process (plural: fimbriae)
• fimbriate – Fringed.
• fissure – A split or crack, often referring to fissured bark; a line or opening of dehiscence.
• fistule – A tube-shaped cavity.
• fistulose – Hollow; usually applied to a tube-shaped cavity, as in a reed.
• flabellate – Fan-shaped.
• flaccid – Limp; tending to wilt. Compare turgid.
• flavonoids – plant compounds that are found in almost all fruits and vegetables. … Along with carotenoids, they are responsible for the vivid colors in fruits and vegetables. Flavonoids are the largest group of phytonutrients, with more than 6,000 types. Some of the best-known flavonoids are quercetin and kaempferol.  Flavanols are a class of flavonoids that have the 3-hydroxyflavone backbone. 
• flexistyly – Depending on the degree of maturation of the stamens, the style moves up or down (cataflexistyle or (ana-)hyperflexisyle).
• flexuous (flexuose) – Bent alternately in different directions; zig-zag.
• floccose – Having soft and woolly tufts of hairs that tend to rub off easily.
• floral leaves – The upper leaves at the base of the flowering branches.
• floral diagram – A graphical means to describe flower structure, usually a schematic cross-section through a young flower.
• floral formula – A description of flower structure using numbers, letters and various symbols.
• floral tube – An imprecise term sometimes used as a synonym of hypanthium or corolla or calyx tube.
• floret – A small flower, usually referring to the individual true flowers clustered within an inflorescence, particularly those of the grasses and the pseudanthia of daisies.
• foetid – malodorous or offensive smelling
• foliaceous – Leaf like in texture and form, but not a leaf (eg petals, stamen)
• foliate – Preceded by a number: having a certain number of leaflets; ie 3-foliate, “having three leaflets“
• foliicolous – A growth habit of certain lichens, algae, and fungi that grow on the leaves of vascular plants.
• follicle – A dry fruit formed from one carpel, splitting along a single suture, to which the seeds are attached. Compare pod (of legume).
• follicetum – An aggregation of follicles, as in Caltha.  Also schizocarpic follicles. 
• foliole – A small leaf-like appendage on the front or back.  Foliolose – bearing folioles. 
• foliose – Leaf-like; flattened like a leaf.
• forb – Any non-woody flowering plant that is not a grass, sedge, or rush.
• forma (in common usage, form) – A taxonomic category subordinate to species and within the taxonomic hierarchy, below variety (varietas), and usually differentiated by a minor character.
• foveolate – Having regular tiny pits. Compare faveolate.
• free – Not united with other organs of the same type; not attached at one end.
• free central – Of placentation, ovules attached to a free-standing column in the centre of a unilocular ovary.
• frond – A leaf of a fern, cycad, or palm.
• frutescent – Shrub-like (fruticose) or becoming shrub-like.
• fruticose – Shrubby; having the branching character of a shrub.
• fruit – A seed-bearing structure present in all angiosperms, formed from the mature ovary and sometimes associated floral parts upon fertilization.
• fugacious – Disappearing, falling off, or withering. Compare persistent and caducous.
• funicle (funiculus) – The stalk of an ovule.
• funnelform – Having a form gradually widening from the base to apex; funnel-shaped.
• furcate – Forked, usually applied to a terminal division; with two long lobes.
• fused – Joined together.
• fusiform – Rod-shaped and narrowing gradually from the middle towards each end; spindle-shaped.

G

• galbulus – In gymnosperms, a fleshy cone (megastrobilus); chiefly relates to cones borne by junipers and cypresses, which are often mistakenly called berries.
• gamete – A cell or nucleus that fuses with another of the opposite sex during sexual reproduction.
• gametophore – Specialized structures on the gametophytes of some bryophytes, for example many  Marchantiales; in such species the gametes are produced on the gametophores, which amount to sex organs.
• gametophyte – The haploid multicellular phase in the alternation of generations of plants and algae that bears gametes. In bryophytes the gametophyte is the dominant vegetative phase; in ferns and their allies it is a small free-living plant known as the prothallus; in gymnosperms and angiosperms the gametophytes are reduced to microscopic structures dependent on the sporophyte, male gametophytes contained in pollen grains and females contained within the ovules.
• gemma – an asexual reproductive structure found in liverworts and mosses.
• gamopetaly/gamopetalous –  petals joined or connate
• gamosepaly/gamosepalous –  sepals joined or connate
• geniculate – bent abruptly, knee like 
• geoflorous – flower heads that are born near ground level, stalkless
• geophilous – Growing or rooting in the ground.
• geophyte – A perennial plant, for example the potato or daffodil, which in spring propagates from an underground organ such as a bulb, tuber, corm or rhizome.
• germination – 1.  of seeds, describing the complex sequence of physiological and structural changes that occur from resting to growth stage.  2.  of a pollen grain; production of a pollen tube when contacting a stigma receptive to it.  3.  of a spore of fungi/bacterium; change of state – from resting to vegetative.
• gibbous (gibbose) – (of part of an organ) Swollen, usually with a pouch-like enlargement at the base.
• glabrescent – Becoming glabrous, almost glabrous.
• glabrous – 1.  Lacking surface ornamentation such as hairs, scales or bristles; smooth. 2.  In lichenology, having no indumentum.
• gland – A secretory structure within or on the surface of a plant. A glandule is a small gland.
• glandarium – a schizocarp of glandetums (pseudocarp) with accrescent receptacle.
• glans – Nut subtended by a cupulate, dry involucre, as in Quercus. (accessory structure Involucre), sometimes referred to as a calybium, but a calybium lacks the accessory.
• glandular hair – A hair tipped with a gland.
• glaucous – Describes the external surface of a plant part that has a whitish covering, in some cases with a bluish cast. Often applied to plants with a woolly or arachnoid surface, but properly referring to pruinose surfaces, meaning those with a waxy bloom. The surface of the young leaves of many eucalyptus provide good examples, and so do some xerophytes.
• globose/globulose – Also globular. Roughly spherical.
• glochid – A tiny barbed hair or bristle, e.g. the fine defensive hairs in cactus species such as Opuntia.
• glomerules – adj: glomerate Dense compact cluster of flowers formed by condensation of a cyme, eg Cornaceae, Fagacea
• glumes – glume – bracts subtending the floret(s) of a sedge, or similar plant; in grasses forming the lowermost organs of a spikelet (there are usually 2 but 1 is sometimes reduced; or rarely, both are absent).
• glutinous – Sticky, about the same as viscid or viscous.
• graminoid – granular (of a surface) Covered with small rounded protuberances.
• graminaceous – Pertaining to, or resembling, the grasses; often used in relation to growth
• guard cell – Each of two cells surrounding the stoma which control gas exchange between the apoplast of the plant and the external environment.
• guttate – Having droplet-shaped spots. Compare punctate and maculate.
• guttation – the secretion of liquid water from uninjured plant parts. See hydathode.
• guttulate – Having or appearing to be spotted with oil droplets; of spores, having oil droplets inside.
• gynobasic – Of a style, arising near the base of the gynoecium, e.g. between the lobes of the ovary.
• gynodioecious – where some plants bear only bisexual flowers and others bear only female flowers.
• gynomonoecious – Of a species, with bisexual flowers and female flowers on the same plant.
• gynoecium – The collective term for the female reproductive parts of a flower or for the carpels of a flower, whether united or free. Contrast androecium. Abbreviation: G. For instance, G indicates a superior ovary; G(5) indicates having five fused carpels.
• gynophore – A stalk supporting the gynoecium and situated above the level of insertion of floral parts, formed from growth of receptacle, whereas a stipitate gynoecium is a stalk that is formed from an elongated ovary.
• gynostegium – A compound organ in milkweeds (Asclepiadaceae) and orchids formed by fusion of the filaments of the stamens with the style and stigma. Also known as the column.
• gynostemium – compound structure formed by the fusion of the stamens and pistil into a single organ.  Is this a synonym of gynostegium or is this more fused than the other?

H

• habit – The general external appearance of a plant, including size, shape, texture and orientation.
• hafter – A flat attachment that forms when the thallus of a fruticose or foliose lichens comes in contact with a substrate, different from rhizines and hapters.
• hair – A single elongated cell or row of cells borne on the surface of an organ.
• half-inferior – Of ovary, partly below and partly above the level of attachment of the other floral parts. Compare inferior, superior.
• halonate – Having a transparent coating, or being of a spore‘s outer layer.
• halophyte – A plant adapted to living in highly saline habitats; accumulates high [] of salt in its tissues.
• haplostemonous – Having a single series of stamens equal in number to the proper number of petals, and alternating with them. Compare diplostemonous, obdiplostemonous.
• hapter – An attachment that may form when a foliose lichen thallus comes in contact with a substrate.
• harmomegathy – process by which pollen in arid environments close off their apertures to conserve water
• hastate – Triangular in outline, the basal lobes pointing outwards, so the base appears truncated; may refer only to the base of a leaf. Compare sagittate which refers to basal lobes pointing backwards.
• haustorium – haustoria or haustorial roots – in parasitic plants, a structure developed for penetrating the host’s tissues. 
• head – See capitulum, a pseudanthium.
• helicoid – Coiled; of a cymose inflorescence, when the branching is repeatedly on the same side (the apex is often recurved), synonym drepanium. Compare scorpioid cyme. Adj: helically 
• helophyte – adj: helophytic – helophyte (plural helophytes) Any plant typically found in marshy ground whose buds overwinter under water.
• hemi-legume – A legume fruit in which the seed or seeds and one valve of the pod are dispersed as a unit. The valve catches the wind and blows away with the seeds, as in Acacia tenuifolia, Peltogyne paniculata.
• hemiparasitic – a plant (such as mistletoe) that possesses chlorophyll and typically carries out photosynthesis but is partially parasitic on the roots or shoots of a plant host: semi parasitic hemiparasite  species — compare holoparasitic.
• hemitropous – half inverted, half amphitropous, when ovule is half inverted so that raphe terminates about halfway between the chalaza and the orifice.
• herb – Any vascular plant that does not develop a woody stem at any point during its life cycle, 
• herbaceous – Not woody; usually green and soft in texture.
• hermaphrodite – A synonym of bisexual.
• hesperidium – A thick-skinned septate berry with the bulk of fruit derived from glandular hairs, eg Citrus.
• heteranthery – adj. heterantherous – the presence of different types of stamens in a flower,
• heteroblastic – Having parts, especially leaves, that are distinctly different between juvenile and adult.
• heteromorphic – Having two or more distinct morphologies (e.g. of different size and shape).
• heteromycotrophic – (adjective heteromycotrophic) – a plant that is a mycotroph as part of its method of nutrition, usually with inadequate photosynthesis and hence often not green; a facultative mycotroph
• heterophyllous – plants with more than one type of leaf 
• heterospory – The production of spores of two different sizes (small and large) by sporophytes of plants
• heterostyly – The condition of a species having flowers with different style and stamen lengths, but with all the flowers of any one plant being identical. see:distyly.  Adj: heterostylous. Contrast homostylous plants with only one type of flower (normal condition).  Also heterodistylous sometimes used for 2 different types.
• heterothetic compound raceme – a compound raceme not terminating in a raceme; a panicle.
• hilum – The scar on a seed coat where it separates from its stalk (funicle).
• hip – The fruit of a rose; an aggregation of achenes surrounded by an urceolate receptacle and hypanthium, as in Rosa. (accessory structures Receptacle and Hypanthium)
• hippocrepiform – Horseshoe-shaped.
• hirsute – Bearing coarse, rough, longish hairs. See indumentum.
• hispid – Bearing long, erect, rigid hairs or bristles, harsh to touch; hispidulous is minutely hispid w sparse or short rigid hairs.
• hoary – covered with a greyish to whitish layer of very short, closely interwoven hairs, frosted appearance; similar to canescent, sometimes used interchangeably.
• holarctic – the biogeographic realm that encompasses the majority of habitats found throughout the northern continents of the world, most of the northern hemisphere. 
• holoparasitic – a parasitic plant (such as dodder) not capable of photosynthesis and obtains all nutrients and water from a host plant In addition to being the only angiosperms lacking leaves. Also holoparasite  
• holotype – A type chosen by the author of a name. Compare lectotypes.
• homeothetic compound raceme – a compound raceme terminating in a raceme; a panicle.
• homochlamydeous – Having a perianth which is not divided into a separate calyx and corolla. Contrast dichlamydeous.
• homodromous – Running in the same direction, ie twining stems, succession of leaves etc 
• homologies – also homologous – similarity of the structure, physiology, or development of different species of organisms based upon their descent from a common evolutionary ancestor.
• hyaline – Translucent; usually delicately membranous and colourless.
• hybrid – A plant produced by the crossing of parents belonging to two different named groups, e.g. genera, species, varieties, subspecies, forma and so on; i.e. the progeny resulting within and between two different plants. An F1 hybrid is the primary product of such a cross. An F2 hybrid is a plant arising from a cross between two F1 hybrids (or from the self-pollination of an F1 hybrid).
• hydathodes  – water secreting pores found on epidermis of leaf margins in some aquatic species. 
• hydrophily – A form of pollination whereby pollen is distributed by the flow of waters.
• hydrophyte  – A plant that grows wholly or partly submerged in water. Because they have less need to conserve water, hydrophytes often have a reduced cuticle and fewer stomata.
• hydroxyl – in chemistry this is an OH- (oxygen and hydrogen atom bonded together) functional group that attaches to some molecules affecting it’s chemistry. For example alcohols contain a hydroxyl group and some phytochemicals possess hydroxyl. 
• hygrophyte – A plant which grows in wet conditions or water logged soil. 
• hygroscopic – a plant sensitive to moisture; caused by moisture; moving when moistened and then dried, as the elaters of Equisetum or the peristome of mosses.
• hymenoptera – a large order of insects that includes the bees, wasps, ants, and sawflies. These insects have four transparent wings and the females typically have a sting.
• hypanthium – A tube or cup-like structure in a flower that includes the bases of sepals, petals, and stamens, and may or may not be connected (adnate) to the ovary.
• hyper-resupinate – In botany, describing leaves or flowers that are in the usual position, but are borne on a petiole or pedicel, respectively, that is twisted 360 degrees. The term is used to describe organs, such as orchid flowers, that are usually resupinate. Compare resupinate.
• hypocarpium – An enlarged fleshy structure that forms below the fruit, from the receptacle or hypanthium.
• hypocotyl – Of an embryo or seedling, the part of the plant axis below the cotyledon and node, but above the root. It marks the transition from root to stem development.
• hypocrateriform – salvershaped: a corolla consisting of a straight tube surmounted by a flat and spreading limb, as in the cowslip and phlox.
• hypercrateriform – a corolla tube that spreads abruptly.  See salverform. 
• hypodermis – the tissue immediately beneath the epidermis of a plant especially when modified to serve as a supporting and protecting layer. 
• hypogynous – Borne below the ovary; used to describe floral parts inserted below the ovary‘s level of insertion. Compare epigynous, perigynous.
• hypothallus – the hypothallus is the outgrowth of hyphae from under the margin of the thallus of a crustose lichen, connecting the island-like areoles into a single lichen.
• hysteranthous – A type of growth in which new leaves appear after flowering. Also spelled histeranthous. Compare proteranthous and synanthous.

I

• idioblast – A cell, especially of a leaf, differing markedly from surrounding cells. They often synthesize specialized products such as crystals.
• imbricate – From the Latin for “tiled”. Overlapping each other; of perianth parts, edges overlapping in the bud (the convoluted arrangement is a special form of imbrication). Dormant buds of many deciduous species are imbricately covered with protective cataphylls called bud scales.
• imparipinnate – Pinnate leaf with an odd # of pinnae (terminated by single leaflet). Compare paripinnate.
• incertae sedis – Of unknown taxonomic affinity; relationships obscure.
• Incised – Cut deeply and (usually) unevenly (a condition intermediate between toothed and lobed).
• included – Enclosed, not protruding, e.g. stamens within the corolla.
• incomplete flower – A flower which lacks one or more of its usual parts (petals, sepals, stamens, pistil)
• incurved – Bent or curved inwards; of leaf margins, when curved towards the adaxial side.
• indefinite – variable in number, and as a rule numerous, e.g. more than twice as many stamens as petals or sepals, but no particular standard number of stamens. In another usage it is a synonym for the preferable term indeterminate, meaning the condition in which an inflorescence is not terminated by a flower, but continues growing until limited by physiological factors. Compare numerous. Contrast definite.
• indehiscent – Not opening in any definite manner at maturity; usually referring to fruit. Contrast dehiscent.
• indeterminate – usually referring to a stem or inflorescence in which there is no particular terminal bud or meristem that stops growth and ends the extension of the stem, which continues until physiological factors stop the growth. Racemes of some Xanthorrhoeaceae, such as many Aloes, and of many Iridaceae, such as Watsonias, are indeterminate. Contrast determinate.
• indumentum – a collective term for a surface covering of any kind of trichomes, e.g. hairs, scales.
• induplicate – folded upwards, or folded with the two adaxial surfaces together.
• indurated – A soft tissue becoming hardened 
• indusium – 1.membrane covering the sporangia of some ferns. 2. a cup enclosing the stigma Goodeniaceae.
• inferior – of an ovary) At least partly below the level of attachment of other floral parts. Contrast superior.
• inflated – swollen, like a bladder.
• inflexed – bent sharply upwards or forwards. Compare deflexed.
• inflorescence – several flowers closely grouped together to form an efficient structured unit; the grouping or arrangement of flowers on a plant.
• infraspecific – denotes taxonomic ranks below species level, for example subspecies.
• infrageneric – denoting taxonomic ranks below the genus level ie subgenera, sections, and series.
• infructescence – the grouping or arrangement of fruits on a plant.
• infundibular (infundibuliform) – funnel-shaped, for example in the corolla of a flower.
• inrolled – rolled inwards.
• insectivorous – catching, and drawing nutriment from, insects.
• insertion, point of – The point at which one organ or structure (such as a leaf) is joined to the structure which bears it (such as a stem).
• inserted – growing out from
• integument – in general, any covering, but especially the covering of an ovule.
• intercalary – (e.g. of growth) occurring between the apex and the base of an organ
• intercalary meristem – a meristem located between the apex and the base of an organ
• interjugary glands – in pinnate leaves, glands occurring along the leaf rachis between the pinnae (below the single and often slightly larger, gland at or just below the insertion of pinnae). Compare jugary.
• internode – The portion of a stem between two nodes.
• interpetiolar – (of stipules) Between the petioles of opposite leaves, e.g in Rubiaceae.
• interstaminal –  situated between the stamens
• intramarginal – inside but close to the margin, for example a vein in a leaf.
• intrastaminal – inside the stamens or androecium, usually referring to the location of a nectary disk.
• introrse – anther locules opening towards the center of flower (at least in bud). Compare extrorse, latrorse.
• involucel – secondary involucre in compound inflorescences 
• involucre – A structure surrounding or supporting, usually a head of flowers. In Asteraceae, it is the group of phyllaries (bracts) surrounding the inflorescence before opening, then supporting the cup-like receptacle on which the head of flowers sits. In Euphorbiaceae it is the cuplike structure that holds the nectar glands, nectar, and head of flowers, and sits above the bract-like cyathophyll structure. Involucres occur in Marchantiophyta, Cycads, fungi, and many other groups.
• involute – Rolled inwards, for example when the margins of a leaf are rolled towards the adaxial (usually upper) surface. Compare revolute.
• iridescent – Having a reflective coloured sheen produced by structural coloration, as in the speculum of the mirror orchid Ophrys speculum.
• iridoids – a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They are biosynthetically derived from 8-oxogeranial. Iridoids are typically found in plants as glycosides, most often bound to glucose.
• irregular – Not able to be divided into two equal halves through any vertical plane. See also asymmetrical. Compare zygomorphic, actinomorphic, and regular.
• isidium – pl. isidia – A warty of club-like structure in lichens that breaks off and forms new lichens without sexual reproduction. Isidia are dispersed by mechanical means, compare to soredia dispersed by wind.
• isobifacial – (of flat structures, especially leaves) Having both surfaces similar, usually referring to cell types or to the number and distribution of stomata.
• isobilateral – leaves are parallel to the main axis and to the direction of the sun.  Common in monocots 
• isomerous – Having an equal number of parts in the whorls. Anisomerous having unequal # of parts
• isophyllous – having leaves on the plant that are all the same. Compare anisophyllous. 
• isostemous – number of stamens equals the number of petals or sepals 
• isotomic – Having branches of equal diameter. Compare anisotomic.

J

• jugary – associated with a jugum or something yoke-like; see for example jugary gland.
• jugary gland – A gland occurring on the rachis of a pinnate or bipinnate leaf on a jugum, the junction or attachment of pairs of pinnae or pinnules, as in some Acacia species. Compare interjugary.
• jugate – yoke-like; describing a structure of paired items joined together as in a jugum or something yoke-like, such as some leaves and fruit.
• jugum – applied to various yoke-like organs, usually in the sense of their being paired, such as a pair of pinnae on a rachis.

K

• K, K+, K- – In lichenology, “K” is the abbreviation for the outcome of a test in which a 10% solution of potassium hydroxide (KOH — hence “K”) is placed on lichen tissues. Color change is noted by “K-” for none, and K+ for a yellow to red or purple color.
• k – strategists – species whose populations fluctuate at or near the carrying capacity (K) of the environment they live in. K-selected species typically have long gestation periods, slow maturation, and long life spans. They are sometimes referred to as equilibrium species.
• keel – adj. Keeled – A prominent longitudinal ridge like the keel of a boat, e.g. the structure of the corolla formed by the fusion of the lower edge of the two abaxial anterior petals of flowers in the Fabaceae.
• key innovation – A novel phenotypic trait that allows subsequent evolutionary radiation and success
• Klausenfrucht – Klausen or Klausenfrucht (German) is a special type of fruit in Lamiaceae and Boraginaceae. A dry, dehiscent fruit formed from a superior ovary with axile or basal placentation, with an adherent calyx, from more than one carpel and usually breaking apart into 1-seeded units by separating each carpel by false septa. One unit is a half carpel, mostly there are four units, seeds. English terms are eremocarp, schizocarp, mericarp or nutlets.
• knee – abrupt bend in a root or stem, commonly at a node; a cypress knee, or pneumatophore, is a type of bend or knob in the root of some plants, especially conifers such as some of the Taxodioideae, that shows as a projection of the root above ground level or mud level.

L

• labellum – lip; one of three or five petals which is (usually) different from the others, e.g. in Orchidaceae, Zingiberaceae, Cannaceae and Stylidiaceae.
• labiate – lipped; where a corolla is divided into two parts, called an upper and lower lip, the two resembling an open mouth with lips.
• lacerate – jagged, as if torn.
• lacinia – In foliose lichens, a linear to elongate lobe, usually arising from or at the end of a larger lobe
• laciniate – Of lobes – with ends irregularly divided into deeply divided, narrow, pointed segments; Of margins – deeply divided into pointed segments in an irregular manner.
• lactones – a phytochemical of cyclic esters, a ring of two or more carbon atoms and a single oxygen atom with a ketone group at one of the carbons adjacent to the other oxygen. 
• lacuna – An empty space, hole, cavity, pit, depression, or discontinuity.
• lamella – a thin, plate-like layer. (pl. lamellae; adjective lamellate composed of an assemblage of layers)
• lamina – the blade of a leaf or the expanded upper part of a petal, sepal or bract.
• laminal – of, or pertaining to, the upper surface, such as the cortex of a lichen.
• lanate – covered in or composed of woolly hairs; synonym of woolly.
• lanceolate – longer than broad, narrowly ovate, broadest in the lower half and tapering to the tip, like a lance or spear head; (sometimes, and incorrectly, used to mean narrowly elliptic).
• lapachol – natural phenolic compound isolated from the bark of the lapacho tree that causes skin irritation upon contact. 
• lateral – attached to the side of an organ, e.g. leaves or branches on a stem. For more detail see dorsal.
• laterocytic – stomata orientation with The guard cells were surrounded by a ring of subsidiary cells in the laterocytic type 
• latex – a milky fluid that exudes from such plants such as spurges, figs and dandelions.
• laticiferous – latex-bearing, producing a milky juice.
• latrorse – a type of anther dehiscence in which the anthers open laterally toward adjacent anthers. cf. introrse, extrorse.
• lauroid – resembling Laurus, the laurel genus, particularly its leaves.
• lax – loose, not compact. Of bundles of hyphae in lichens – not stiff and not agglutinate.
• leaf gap – a parenchymatous area in the stele above (distal to) a leaf trace.
• leaf opposed – when an inflorescence is born at a node opposite the leaf (not in the axil), seen in some epiphytes. 
• leaf scar – A healing layer forming on a stem where a leaf has fallen off.
• leaf trace – A vascular bundle connecting the stele to a leaf.
• leaflets – The ultimate segments of a compound leaf.
• lecanorine – of lichens, having apothecia with rims of tissue similar to the tissue of the thallus (Lecanora)
• legume – 1.  a fruit characteristic of the family Fabaceae, formed from one carpel and either dehiscent along both sides, or indehiscent. 2.  a crop species in the family Fabaceae. 3. a plant of the family Fabaceae. 
• lemma – the lower of 2 bracts enclosing a grass flower.
• lenticels – one of many raised pores in the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues
• lenticular – 1.  lens-shaped.  2.  covered in lenticels
• lepidote – covered with small scales.
• leprose – powdery
• leptocaul – growth form where the tree is branched many times, stems and leaves not usually large. 
• liana – a woody climbing plant, rooted in the ground (liane is also used).
• libriform – of a fibre of woody tissue, elongated and having a pitted thickened cell wall.
• lichenicolous – growing on or in lichens, often but not necessarily as parasites
• ligneous / Lignified – having hard lignified tissues or woody parts, woody
• lignum – Dead wood, typically in the context of a substrate for lichens.
• lignicolous – Growing on wood tissue after bark as fallen or been stripped off (compare to corticolous)
• lignotuber – a woody swelling of the stem below or just above the ground; contains adventitious buds from which new shoots can develop, e.g. after fire.  Lignotuberous. 
• ligulate – 1.  bearing a ligule.  2.  strap-shaped. Also eligulate is without a ligule. 
• ligule – 1.  A small membranous appendage on the top of the sheath of grass leaves.  2.  A minute adaxial appendage near the base of a leaf, e.g. Selaginella.  3. An extended, strap-like corolla in some daisy florets.
• linear – Very narrow in relation to its length, with the sides mostly parallel. See Leaf shape.
• lithophytic –  plant growing on rocks; an epilithic plant.
• lobe – adj: lobate. Part of a leaf (or other organ), often rounded and formed by incisions to about halfway to the midrib.
• lobulate – Having small lobes 
• loculicidal – A capsule that dehisces longitudinally into the center cavity of the locule, as in Epilobium. Compare septicidal.
• locule – A chamber containing seeds within an ovary, pollen within an anther or spores in a sporangium.
• lodicule – One of two or three minute organs at the base of the ovary of a grass flower, representing parts of a strongly reduced perianth.
• lomentum or loment – A pod-like indehiscent fruit that develops constrictions between the segments and at maturity breaks transversely into one-seeded segments instead of splitting open, a type of schizocarpic fruit. lomentaceous = adj. 
• longicidal – (of anthers) Opening lengthwise by longitudinal slits. Compare poricidal.
• lunate – Crescent-shaped.
• lumen – The cavity bounded by a plant cell wall.
• lumpers – taxonomists who prefer to lump more related genera together in the same more variable family rather than split them into smaller less variable families (the splitters).  
• lyrate – Lyre-shaped; deeply lobed, with a large terminal lobe and smaller lateral ones.
• lysigenous – Formed by the breaking down of adjoining cells; often applied to secretory cells 

M

• maculate – stained, spotted, compare immaculate
• malacophilous – pollination by slugs
• mallee – A growth habit in which several woody stems arise separately from a lignotuber; a plant with such a growth habit, e.g. many Eucalyptus species; vegetation characterized by such plants.
• mangrove – Any shrub or small tree growing in salt or brackish water, usually characterized by pneumatophores; any tropical coastal vegetation characterized by such species.
• marcescent – Retention of dead plant organs that are normally shed
• margin – the edge of a structure, as in the edge of a leaf blade.
• marginal – Occurring at or very close to a margin.
• mast – Edible fruit and nuts produced by woody species of plants (e.g. acorns and beechmast) which is consumed on the ground by wildlife species and some domestic animals.
• mealy – Covered with coarse, floury powder.
• medulla – 1.  In a lichen, the typically undifferentiated tissue underneath the cortex of the thallus, or between the upper and lower cortex if both are present. The medulla is analogous to the tissues underneath the epidermis (skin) of a leaf. The uppermost region commonly contains most of the photobionts.  2.  pith. See also medullary rays in wood.
• medifixed – attached by the middles, as in anthers. 
• megasporangium – the larger of two kinds of sporangium produced by heterosporous plants, producing large spores that contain the female gametophytes. Compare microsporangium.
• megaspore – the larger of two kinds of spores produced by a heterosporous plant, giving rise to the female gametophyte. Compare microspore.
• megasporophyll – in heterosporous plants, a modified leaf bearing one or more megasporangia. Compare microsporophyll.
• megastrobilus – the larger of two kinds of cones or strobili produced by gymnosperms, being female and producing the seeds. Compare microstrobilus.
• membranous – thin, translucent and flexible, seldom green.
• mericarp – one segment of a fruit (a schizocarp) that splits at maturity into units derived from the individual carpels, or a carpel, usually 1-seeded, released by the break-up at maturity of a fruit formed from 2 or more joined carpels.
• meristem – Any actively dividing plant tissue.
• mesic – Moist, avoiding both extremes of drought and wet; pertaining to conditions of moderate moisture or water supply; applied to organisms (vegetation) occupying moist habitats.
• mesocarp – The fleshy portion of the wall of a succulent fruit inside the skin and outside the stony layer (if any), surrounding the seed(s); sarcocarp.
• mesomorphic – soft and with little fibrous tissue, but not succulent.
• mesophyll – 1.  The parenchyma tissues between the upper and lower epidermis. They vary in function, but usually include the photosynthetic tissue of a leaf  2.  In ecology, the blade of a leaf or leaflet that has a surface area 4500–18225 mm2; a plant, or vegetation, that has mesophyll (sized) leaves.
• mesophyllous – (of vegetation) Of moist habitats and having mostly large and soft leaves.
• mesophyte – A plant thriving under intermediate environmental conditions of moderate moisture and temperature, without major seasonal fluctuations.
• micropyle – an opening at the apex of an ovule.
• microsporangium – The smaller of two kinds of sporangium produced by a heterosporous plant, producing microspores that contain the male gametophyte. Compare megasporangium.
• microspore – The smaller of two kinds of spores produced by a heterosporous plant. Compare megaspore.
• microsporogenesis – The formation of microspores inside the microsporangia of seed plants. A diploid cell in the microsporangium, called a microsporocyte, undergoes meiosis and gives rise to four haploid microspores.
• microsporophyll – Heterosporous plants modified leaf bearing 1+ microsporangia. Com: megasporophyll
• microstrobilus – The smaller of two kinds of cones or strobili produced by gymnosperms, being male and producing the pollen. Compare megastrobilus.
• midrib – Also midvein. The central and usually most prominent vein of a leaf or leaf-like organ.
• mid petaline band – a band on the petals of some flowers – eg Ipomoea
• mixotrophic – plants gaining energy from both photosynthesis and mycorrhizal fungi; an autotroph and a parasite.  
• monad – A single individual that is free from other individuals, not united with them into a group. The term is usually used for pollen to distinguish single grains from tetrads or polyads.
• monocot – also monocotyledon – as the name implies, are defined by having seeds that contain a single (mono-) embryonic leaf known as a cotyledon. This is a monophyletic group that constitutes a majority of our agricultural biomass and include many important crop staples including, but not limited to, rice, wheat, corn, sugar cane, bamboo, onion, and garlic.  Monocots differ from dicots in six distinct structural features the flowers (parts usually in 3’s), leaves (usually parallel vein), roots (usually adventitious with storage organs), stems (lack secondary growth, different vascularization), and pollen grains (monosulcate, meaning that the pollen has a single furrow or pore through the outer layer.). But the root of these differences stem from the very early embryonic stages of the angiosperm, providing the biggest difference of all between monocots and dicots, is the seed. Note there are always exceptions to the rule. Some monocots may have a feature typically found in dicots, or vice versa and approximately 2% of angiosperms don’t fit into either the monocot or the dicot category and are classified in this book as basal angiosperms.
• moniliform – Resembling a string of beads.
• monocarpic – Flowering and setting seed only once before dying. See also semelparous.
• monochasium – A cymose inflorescence with branches arising singly. Compare dichasium, pleiochasium.
• monochlamydeous – Flowers with only one set of floral envelopes, ie either a corolla or a calyx 
• monoecious – (of vascular plants) Hermaphroditic, with all flowers bisexual, or with male and female reproductive structures in separate flowers but on the same plant, or of an inflorescence that has unisexual flowers of both sexes. Contrast dioecious.
• monoicous – (of bryophyte gametophytes) Hermaphroditic or bisexual, where both male and female reproductive structures develop on the same individual. Contrast dioecious.
• monogeneric – (of a genus or species) consisting of only one type of animal or plant.
• monograph – Of a group of plants, a comprehensive treatise presenting an analysis and synthesis of taxonomic knowledge of that taxon; the fullest account possible (at the time) of a family, tribe or genus. It is generally worldwide in scope and evaluates all taxonomic treatments of that taxon including studies of its evolutionary relationships with other related taxa, and cytological, genetic, morphological, palaeobotanical and ecological studies. The term is often incorrectly applied to any systematic work devoted to a single taxon. Compare revision.
• monomerous – monomeric – Gynoecium consisting of a single carpel, not fused. 
• monomorphic – Of one type, rather than several. See dimorphic (two types), polymorphic (many types).
• monophyletic – or monophylogeny, is a term used to describe a group of organisms that are classified in the same taxon and share a most common recent ancestor. A monophyletic group includes all descendants of that most common recent ancestor.
• monophyllous – Having a single leaf.
• monopodial – A mode of stem growth and branching in which the main axis is formed by a single dominant meristem. Contrast sympodial.
• monostromatic – Being a single cell thick, as in the alga Monostroma.
• monosulcate – of pollen has a single furrow or pore through the outer layer.
• monothecal – having a sole compartment or cell. a monothecal stamen/anther. 
• monotypic – Containing only one taxon of the next lower rank, e.g. a family with only one genus (also referred to as monogeneric), or more often applied to a genus that includes only a single species.
• morphology – The shape or form of an organism or part thereof.
• mucro – Diminutive: mucronule. Sharp, short point, at the tip of the leaf or the tip of the midrib of compound leaf.
• mucronate – Terminating in a mucro (a sharp stiff point).
• multiple fruit – A cluster of fruits produced from more than one flower and appearing as a single fruit, often on a swollen axis, as with many species of the family Moraceae. Compare aggregate fruit.
• muricate – Covered with short hard protuberances.
• muticous – lacking an awn, spine or point
• mycelium – The “vegetative” (nonreproductive) part of a fungus, mostly composed of aggregations of hyphae. It functions in substrate decomposition and absorption of nutrients.
• mycobiont – The fungal component of a lichen. Compare photobiont.
• mycorrhiza – pl. mycorrhizae; adj. mycorrhizal One of several types of symbiotic association between a fungus and the roots of a plant.
• mycotroph – adj. mycotrophic – A plant that obtains most or all of its carbon, water, and nutrients by associating with a fungus.
• mycoheterotroph – Mycoheterotrophy is a symbiotic relationship between certain kinds of plants and fungi where the plant gets all or part of its food from parasitism upon fungi instead of or as well as photosynthesis. A mycoheterotroph is the parasitic plant partner and the interface between the two is the roots of the plant and the mycelium of the fungus, closely resembling mycorrhiza except that the flow of carbon is from the fungus to the plant instead of vice versa.
• myriophyllin – Idioblasts (myriophyllin cells) with condensed tannins present in some species.
• myrosin – When herbivores damage plant tissues, myrosinase released from myrosin cells catalyzes hydrolysis of glucosinolates to produce toxic compounds against herbivores. Myrosin cells specifically develop adjacent to phloem cells (on the abaxial side of vasculature) and are called myrosin phloem cells.

N

• nectar – Usually sweet, nutrient-rich fluid produced by the flowers of many plants and collected by insects.
• nectary – adj. Nectariferous, nectaries – A specialized gland that secretes nectar.
• neophyte – A plant that has recently been introduced to a geographic area. Contrast archaeophyte.
• neoteny – arresting of normal development of all cells except the germ line, resulting in sexually mature organisms with juvenile characteristics.  
• neotropical – denoting a phytogeographical kingdom comprising Central and South America but excluding the southern parts of Chile and Argentina and excluding most of Mexico. 
• nerve – Another name for a vein.
• node – The part of a stem from which leaves or branches arise.
• Nomen conservandum – (Latin) A conserved name, usually a name that became so much better known than the correct name, that a substitution was made.
• nucellus – the tissue of the ovule of a seed plant that surrounds the female gametophyte. It is enclosed by integuments and is not of epidermal origin.
• nucleotide – an organic molecule that is the building block of DNA and RNA that also function in cell signaling, metabolism and enzymatic reactions. A nucleotide is made up of three parts: a phosphate group, a 5-carbon sugar and a nitrogenous base.
• nuculanium – a dry drupe composed of a thin outer layer (exocarp), a thick, fibrous middle layer (mesocarp), and a hard inner layer (endocarp) surrounding a large seed. As in coconuts.  The “meat” of the seed is endosperm tissue and a small, cylindrical embryo is embedded in this nutritive tissue. “Coconut water” is a liquid endosperm that has not developed into solid tissue composed of cells. 
• nucular – Nut-shaped; of or relating to a nucule — a section of a compound (usually hard) fruit.
• numerous – Stamens are described as numerous when there are more than twice as many as sepals or petals, especially when there is no set number of them. Compare indefinite
• nut – A one-seeded, dry, indehiscent (does not split at maturity) fruit with a hard pericarp, usually derived from a one-loculed ovary. 
• nutlet – 1.  A small nut.  2.  One of the lobes or sections of the mature ovary of some members of the Boraginaceae, Verbenaceae, and Lamiaceae.
• nyctinastic – the periodic movement of flowers or leaves caused by nightly changes in light intensity or temperature; these same plants usually also respond to touch (ie: Mimosa).

O

• ob– A prefix meaning “inversely”; usually the same shape as that described by the word stem, but attached by the narrower end. See obcordate, oblanceolate and obovate.
• obconic – (of a fruit, hypanthium, pistil, or calyx) Shaped like an inverted cone, attached at the apex.
• obcordate – (of a leaf blade) Broad and notched at the tip; heart-shaped but attached at the pointed end.
• obdeltate – triangular leaf blade broader at the tip then then base.
• obdiplostemonous – Having stamens arranged in two whorls, and having twice as many stamens as petals, with the outer whorl being opposite the petals. Compare diplostemonous, haplostemonous.
• oblanceolate – Having a lanceolate shape but broadest in the upper third.
• obligate – (of parasites) Unable to survive without a host. Contrast facultative.
• oblique – Slanting; of a leaf or stem, larger on one side of the midrib than the other; asymmetrical.
• obloid – Having a three-dimensional oblong shape, e.g. a fruit.
• oblong – Having a length a few times greater than the width, with sides almost parallel and ends rounded.
• obovate – (of a leaf) Having a length about 1.5 times the width, and widest above the centre.
• obsolete -Not evident, or at most rudimentary or vestigial.
• obturator – Part of the ovary that chemically guides the pollen tube into the micropyle.
• obtrapeziform – trapeziform, but attached by the narrower trapezoidal base (e.g. of a leaf)
• obtuse – Blunt or rounded; having converging edges that form an angle of more than 90°. Compare with acute.
• ochrea – Also spelled ocrea. Adj: ochreate, ochreolate probably refers to small ochrea on inflorescences. A sheath formed from two stipules encircling the node.  In Polygonaceae, Moraceae, grasses etc 
• odd-pinnate – Also imparipinnate. Having an odd number of leaflets in a compound pinnate leaf, such that there is only one terminal leaflet.
• oligosaccharide – oligosaccharides are any carbohydrate made of 3 to 6 units of monosaccharides (simple single carbohydrate sugars).  Intermediate between monosaccharides and polysaccharides in terms of size, complexity and molecular mass. 
• ontogeny – ontogenetically, ontogenesis, ontogenetic.  The sequence of developmental stages through which an organism passes as it grows.
• operculate capsule – Fruit that dehisces through pores, which are covered by a flap or lid, as in Papaver.
• operculum (calyptra) – A lid or cover that becomes detached at maturity, e.g. in Eucalyptus, a cap covering the bud and formed by the fusion or cohesion of perianth parts.
• opposite – 1.  Describing leaves or flowers borne at the same level but on directly opposite sides of their common axis.  2.  Describing the occurrence of something on the same radius as something else, e.g. anthers opposite sepals. Compare alternate.
• oppositiperianth – adjective. Especially of a stamen placed in front of or opposite the perianth, used with flowers that have tepals instead of sepals and petals. 
• oppositisepalous – adjective. Especially of a stamen placed in front of or opposite the petals or divisions of the corolla.
• oppositisepalous – adjective. Especially of a stamen placed in front of or opposite the sepals or divisions of the calyx.
• orbicular – Flat and more or less circular.
• ornithophilous –  pollination of flowers by birds.
• ortet – The original single parent plant from which a clone ultimately derives.
• orthotropous – When an ovule is erect upright. With the micropyle directed away from the placenta; atropous. Compare amphitropous, anatropous, campylotropous.
• ostiole – pl. ostioles – a small hole or opening through which algae or fungi release their mature spores. The term is also used in higher plants, for example to denote the opening of the fig inflorescence through which fig wasps enter to pollinate and breed.
• oval – See elliptical.
• ovary – The basal portion of a carpel or group of fused carpels, enclosing the ovules.
• ovate – Shaped like a section through the long-axis of an egg and attached by the wider end.
• ovoid – Egg-shaped, with wider portion at base; 3-D object, ovate in through long-axis.
• ovule – Loosely, the seed before fertilization; a structure in a seed plant within which one or more megaspores are formed (after fertilization it develops into a seed).

P

• pachycaul – with a disproportionately thick trunk
• pachycladus – with disproportionately thick stems
• palea – (pl. paleae or paleas) 1.the upper of two bracts enclosing a grass flower, major contributors to chaff in harvested grain. 2. Chaffy scales on the receptacles of Asteraceae. 3. Chaffy scales on the stipe of ferns.
• paleate – Bearing paleae or chaffy scales, as in description of the receptacle of a capitulum of Asteraceae.
• paleaceous – Chaff-like in texture.
• paleotropical – denoting a region comprising the tropical parts of the Old World.
• palmate – 1.  leaf with veins radiating out from a central point (usually at the top of a petiole), resembling spread out fingers pointing away from the palm.  2.  A compound palmate leaf has leaflets that radiate from a central point (usually at the top of a petiole).
• palmatifid – Deeply divided into several lobes arising from more or less the same level.
• palmatisect – Intermediate between palmate and palmatifid, i.e. the segments are not fully separated at the base; often more or less digitate.
• paludal – Growing in marshland 
• panduriform – (of a leaf shape) having rounded ends and a contracted center. fiddle-shaped, pandurate. unsubdivided, simple – (botany) of leaf shapes; of leaves having no divisions or subdivisions.
• panicle – dj. Paniculate – A compound raceme; an indeterminate inflorescence in which the flowers are borne on branches of the main axis or on further branches of these.
• papilionate – papilionaceous – Butterfly-like; having a corolla like that of a pea.
• papilla – pl. papillae; adj. papillose or papillate A small, elongated protuberance on the surface of an organ, usually an extension of one epidermal cell.
• pappus – In daisy florets, a tuft or ring of hairs or scales borne above the ovary and outside the corolla (representing the reduced calyx); a tuft of hairs on a fruit.
• paracytic – Stomata with one or more subsidiary cells parallel to the opening between guard cells 
• parallelodromous – multiple parallel veins originating at base and converging towards apex (ie monocots) 
• paramo – Páramo can refer to a variety of alpine tundra ecosystems above the continuous timberline but more specifically it is a Neotropical high mountain biome with vegetation composed mainly of giant rosette plants, shrubs and grasses.
• paraperigonium – Also paraperigone. An anomalous secondary outgrowth of the perianthal meristem with ramifying vasculature. See also perigonium, perianth, and corona.
• paraphyletic – also paraphyly – a term used in evolutionary biology to describe a group of plants which contains a common ancestor and some, but not all, of the descendants.  
• parasite – An organism living on or in a different organism, from which it derives nourishment. Some plant species are parasitic. Compare saprophyte and epiphyte.
• parenchyma – A versatile ground tissue composed of living primary cells which performs a wide variety of structural and biochemical functions in plants.
• parietal – Attached to the marginal walls of a structure, e.g. ovules attached to placentas on the wall of a syncarpous unilocular ovary. See placentation.
• paripinnate – Having an even number of leaflets (or pinnae), i.e. terminated by a pair of pinnae as opposed to a single pinna. Compare imparipinnate.
• parthenocarpy – The development or production of fruit without fertilization. Compare stenospermocarpy.
• patelliform – Disk shaped with a narrow rim
• patent – Also patulous. Spreading; standing at 45–50° to the axis. See also erecto-patent.
• pauciflor – Having few flowers per inflorescence. Compare pluriflor and uniflor.
• pectinate – Pinnately divided with narrow segments closely set like the teeth of a comb.
• pedate – Having a terminal lobe or leaflet, and on either side of it an axis curving outwards and backwards, bearing lobes or leaflets on the outer side of the curve.
• pedicel – adj. pedicellate The stalk of a single flower; also be applied to the stalk of a capitulum in the Asteraceae.
• peduncle – adj. pedunculate – The stalk of an inflorescence.
• peltate – Shield-like, with the stalk attached to the lower surface and not to the margin; subpeltate is almost peltate.
• pellucid – Transmitting light; for example, said of tiny gland dots in the leaves of e.g. Myrtaceae and Rutaceae that are visible when held in front of a light.
• peloric – Flowers having a mutation such that a normally asymmetric flower becomes radially symmetric. 
• pendulous – Hanging an ovule attached onto a placenta on the top of the ovary. Compare suspended.
• penicillate – Tufted like an artist’s brush; with long hairs towards one end.
• penninervation – adj. penninerved – With pinnately arranged veins.
• pentangular  – 5 sided
• pentamerous – In five parts, particularly with respect to flowers, five parts in each whorl. See also trimerous and tetramerous.
• pepo – A type of berry formed from an inferior ovary and containing many seeds, usually large with a leathery non-septate rind as in Cucurbita.
• perennating – Of an organ that survives vegetatively from season to season. A period of reduced activity between seasons is usual.
• perfect – (of a flower) Bisexual; containing both male and female reproductive parts in the same inflorescence. Contrast imperfect.
• perfoliate – With its base wrapped around perforated the stem (so that the stem appears to pass through it), e.g. of leaves and bracts.
• perforate – With many holes. Used to describe the texture of pollen exine, and also to indicate that tracheary elements have a perforation plate. See also fenestrate.
• perforation plate – in a tracheary element, part of the cell wall that is perforated; present in vessel members but not in tracheids. Should not be confused with a pit.
• perianth – The collective term for the calyx and corolla of a flower (generally used when the two are too similar to be easily distinguishable). Abbreviation: P; for instance, P 3+3 indicates the calyx and corolla each have 3 elements, i.e. 3 sepals + 3 petals.
• pericarp – The wall of a fruit, developed from the ovary wall.
• periclinal – Curved along parallel to a surface. Compare anticlinal.
• pericycle – A cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outermost part of the stele of plants.
• perigone – used in reference to a perianth tube with tepals instead of sepals and petals. 
• perigonium – In flowering plants, synonym of perianth.
• perigynium – A sac from a modified tubular bract, or when fully closed an utricle around the pistillate flower of sedges
• perigynous – Borne around the ovary, of perianth segments and stamens arising from a cup-like or tubular extension of receptacle (free from ovary but extends above its base). Compare epigynous, hypogynous.
• peristem – Nutritive tissue in seeds derived from the nucellus, surrounds the embryo. 
• peristome – an anatomical feature that surrounds an opening to an organ or structure; the one or two circles of small, pointed, tooth-like appendages around the orifice of a capsule or urn of mosses, appearing when the lid is removed.
• persistent – Remaining attached to the plant beyond the usual time of falling, for instance sepals not falling after flowering, flower parts remaining through maturity of fruit. Compare deciduous, caducous.
• personate – bilabiate corolla with 2 lips but with the throat closed by a prominent palate (snapdragon)
• perule – adj. perulate – 1.  The scales covering a leaf or flower bud, or a reduced scale-like leaf surrounding the bud. Buds lacking perulae are referred to as “naked”.  2.  In Camellias the final bracts and sepals become indistinguishable and are called perules.  3.  A kind of sac formed by the adherent bases of the two lateral sepals in certain orchids.
• petal – In a flower, one of the segments or divisions of the inner whorl of non-fertile parts surrounding the fertile organs, usually soft and conspicuously coloured. Compare sepal.
• petaloid – Like a petal; soft in texture and coloured conspicuously.
• petiolar petiolary – Associated with a petiole, as in petiolary glands.
• petiolate – (of a leaf) Having a petiole. Contrast sessile.
• petiole – The stalk of a leaf.  
• petiolule – The stalk of a leaflet in a compound leaf.
• petricolous – Rock-dwelling; living on or among rocks.
• phaneranthous – showy flowers that advertise to pollinators, as opposed to aphananthous (unshowy)
• phanerogam – Gymnosperms and angiosperms; plants producing stamens and gynoecia; literally plants with conspicuous sexual reproductive organs. Compare cryptogams.
• phenolic – are aromatic benzene ring compounds with one or more hydroxyl groups produced by plants mainly for protection against stress. The functions of phenolic compounds in plant physiology and interactions with biotic and abiotic environments are difficult to overestimate. 
• phenology – The study of the timing of seasonal biological phenomena, ie flowering, leaf emergence etc.
• phlobaphene – reddish, alcohol-soluble, water-insoluble phenolic substances that can be extracted from plants or result from treatment of tannin extracts with mineral acids.
• phloem – A specialized conducting tissue in vascular plants, transports sucrose from leaves to other organs.
• photobiont – In a lichen, the component that does the photosynthesis, the green algae (Chlorophyta) or blue-green algae (Cyanobacteria). (compare to mycobiont, the fungal component.) Also called phycobiont.
• photorespiration – a process in plant metabolism where the enzyme RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) oxygenates Ribulose-1,5-bisphosphate (RuBP) wasting some of the energy produced by photosynthesis.
• phototoxic – also phototoxin – Phototoxic effects are usually skin irritation in mammals that stem from chemical exposure by plants, in addition to the presence of light.
• phyllary – An individual bract within an involucre or involucel.
• phyllid – A leaf-like extension of the stem in Bryophytes
• phyllode adj. phyllodineous – A leaf with the blade much reduced or absent, and in which the petiole and or rachis perform the functions of the whole leaf, e.g. many acacias. Compare cladode.
• phyllopodium – (in ferns) A short outgrowth of the stem on which the frond is borne and which remains attached to the rhizome after the frond has been shed.
• phyllotaxy – the arrangement of leaves on a stem or axis.
• phyllosphere – The above-ground surface of plants as a habitat for epiphytic microorganisms.
• phytochemistry –  is the study of phytochemicals, which are chemicals derived from plants. … The compounds found in plants are of many kinds, but most are in four major biochemical classes, the alkaloids, glycosides, polyphenols, and terpenes. Phytochemistry can be considered a sub-field of botany or chemistry.
• phytomelan – Also phytomelanin; adj. phytomelanous A black, inert, organic material that forms a crust-like covering of some seeds, commonly found in Asparagales, Asteraceae, etc.
• phytonutrients – are natural chemicals or compounds produced by plants. They keep plants healthy, protecting them from insects and the sun. 
• phytotoxin – substances that are toxic to the growth of plants; or toxic chemicals produced by plants themselves that function as defensive agents against predators. 
• pileate – Having a cap, a pileus.
• pileus – A cap or cap-shaped structure, such as the cap of mushrooms or the plumule of some monocots.
• piliform -Having the shape of a cap, a pileus.
• pilose – covered with soft, weak, thin and clearly separated hairs, which are usually defined as long and erect and sometimes ascending.
• pinna – (plural pinnae) a primary segment of a compound leaf.
• pinnate – a compound leaf with leaflets arranged on each side of a common petiole or axis; also applied to how the lateral veins are arranged in relation to the main vein.
• pinnatifid – Pinnately lobed.
• pinnatisect – pinnately divided almost to midrib but segments still confluent.
• pinnule or pinnula – Usage varies: ultimate free division (or leaflets) of a compound leaf, or a pinnate subdivision of a multi pinnate leaf.
• piriform – pear shaped. Also spelled pyriform. 
• pistil – 1.  a single carpel when the carpels are free.  2.  a group of carpels when the carpels are united by the fusion of their walls.
• pistillate flower – a flower containing one or more pistils but no stamens. Aka a female flower.
• pistillode – pistillodial.  A sterile or rudimentary pistil.
• pit – In tracheary elements, a section of the cell wall where the secondary wall is missing, and the primary wall is present. Pits generally occur in pairs and link two cells.
• pith – The central region of a stem, inside the vascular cylinder; the spongy parenchymatous central tissue in some stems and roots.
• placenta – The tissue within an ovary to which the ovules are attached.
• placentation – Arrangement of ovules inside ovary; axile, free-central, parietal, marginal, basal, or apical.
• placodioid – The form of a lichen thallus which radiates outward with the ends of the radiating arms peeling up from the substrate, but which lack a cortex on the underside (unlike foliose lichens).
• plastochron – The time between successive leaf initiation events.
• pleiochasium – pl. pleiochasia. An inflorescence in which several buds come out at the same time. cf. monochasium, dichasium.
• plesiomorphic – An ancestral character state
• plicate – Pleated; folded back and forth longitudinally like a fan, such as the leaves of fan palm species; plicate flowers have corollas with folds in them. The concept often appears in specific names in forms such as Kumara plicatilis and Acacia plicata. Commonly such names are not correctly appropriate, but are applied to distichous structures rather than plicate.
• plinerved – (of leaves) A suffix indicating that the main nerves are lateral and arise from a point distinctly above the base of the leaf. Combined with a numerical prefix to form words like 3-plinerved, 5-plinerved, etc. Eg Dissotis of Melastomataceae. 
• plumose – Like a feather; with fine hairs branching from a main axis.
• plumule – The part of an embryo that gives rise to the shoot system of a plant. Compare radicle.
• pluriflor – Having many flowers per inflorescence. See also pauciflor and uniflor.
• pluriovulate – Having many ovules as in placentae, carpels or ovaries.
• pneumatophore – A vertical appendage, aerial at low tide, on the roots of some plants. Pneumatophore functions are unclear, but possibly related to gas exchange, or to root anchoring. Pneumatophores typically occur on mangrove roots, but some versions occur on species of conifers, such as some in the Taxodioideae.
• pod – 1. A legume, the fruit of a leguminous plant, a dry fruit of a single carpel, splitting along two sutures. 2. A siliqua and silicula, fruit of Brassicaceae, a dry fruit composed of two carpels separated by a partition.
• pollen – powdery mass shed from anthers (of angiosperms) or microsporangia (of gymnosperms); the microspores of seed plants; pollen-grains.
• pollinium pl pollinia – pollen-grains cohering by waxy texture or fine threads into a single body or mass. 
• pollinarium – noun. Pl: pollinaria.  The structure in an orchid flower which becomes attached to an insect during pollination. Includes the pollinia, caudicle, and viscidium. 
• pollen transmitting tissue – the tissue in the style of a flower through which the pollen tubes grow.
• pollination – The transfer of pollen from a male organ (such as an anther) to the receptive region of a female organ (such as a stigma).
• polygamodioecious – Having bisexual and male flowers on some plants and bisexual and female flowers on others. Compare androdioecious, andromonoecious, dioecious, monoecious etc.
• polygamomonoecious – having male, female and bisexual flowers on the same plant. Compare androdioecious, andromonoecious, polygamodioecious, polygamous.
• polygamous – having bisexual and unisexual flowers on the same plant.
• polymorphic – Of several different kinds (in respect to shape and/or size), hence polymorphism. See also monomorphic (a single type) and dimorphic (two types)
• polyploid – Also polyploidy – a condition in which the cells of an organism have more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.
• polysaccharides – complex carbohydrates formed from a chain of numerous smaller monosaccharides or oligosaccharides.
• polystemonous  – having numerous stamens; the number of stamens being at least twice the number of sepals or petals, but not strictly three or four times that number.
• polystichous –  arranged in several rows or series.
• pome – A berry-like fruit, adnate to a fleshy receptacle, with cartilaginous endocarp, as in Malus. (accessory structures Receptacle and Hypanthium). Fruit is partly from ovary wall but mostly hypanthium. 
• pomarium –  fruiting receptacle of a schizocarpic fruit divided into many cavities, an aggregate of many apocarps. e.g. Ravensara of Lauraceae, Siparuna of Monimiaceae.
• poricidal – Opening by pores, as in Triodanis.  Note Poppies are often called poricidal, which they are, but their pores are covered by a cap and are called operculate capsules.  Compare longicidal.
• porrect – extending horizontally outward and forwards. 
• posterior – Positioned behind or towards the rear. Contrast anterior.
• posticous – adj: posticously 1. posterior. 2. situated on the outside of an anther (extrorse) 
• precocious – appearing or developing early; example when precocious flowers appear before the leaves
• prickle – Prickly – A hard, pointed outgrowth from the surface of a plant (involving several layers of cells but not containing a vein); a sharp outgrowth from bark, detachable without tearing wood. Compare thorn.
• primary species – In lichens, a species reproducing mainly by sexual reproduction rather than by vegetative reproduction.
• primary vein – The single vein or array of veins that is conspicuously larger than any others in a leaf. In pinnate venation, the single primary vein can generally be found in the middle of the leaf; in palmate venation, several such veins radiate from a point at or near the base of the leaf.
• primordia – an organ or tissue in its earliest recognizable stage of development
• prolate – elongated along the polar diameter (opposed to oblate)
• prop roots – adventitious roots that supports the plant, for example the aerial roots of the mangrove tree or of corn, some palms etc
• propagule – In lichens, a part of the thallus that has both fungal and algal parts and can break off for vegetative reproduction, e.g. an isidium, phyllidium, phyllocladium, or soredium).
• prophyll – A leaf formed at the base of a shoot, usually smaller than those formed later.
• procumbent – Spreading along the ground but not rooting at the nodes; not as close to ground as prostrate.
• propagule – Any structure capable of generating a new plant; includes seeds, spores, bulbils, etc.
• prostrate – Lying flat on the ground; commonly rooting at nodes that touch the soil surface.
• protandrous – Having male sex organs which mature before the female ones, e.g. a flower shedding pollen before the stigma is receptive. Compare protogynous.
• proteinase – An enzyme that breaks down proteins into smaller components. 
• proteranthous – With new leaves appearing before flowers. See also hysteranthous and synanthous.
• prothallus – A #gametophyte plant, usually flattened and delicate, e.g. in ferns and fern allies.
• protocorm – a tuber-shaped body with rhizoids that is produced by the young seedlings of various orchids and some other plants having associated mycorrhizal fungi.
• protogynous – Having female sex organs which mature before the male ones, e.g. a flower shedding pollen after the stigma has ceased to be receptive. Compare protandrous.
• proximal – Adj: proximally – Near the point of origin or attachment. Compare distal.
• pruinose – Covered with a powdery, waxy material; having a bloom.
• pseudanthium – A type of inflorescence occurring in the Asteraceae and Euphorbiaceae, in which multiple flowers are grouped together to form a flower-like structure, commonly called a head or capitulum.
• pseudo– – A prefix meaning “false, not genuine”
• pseudanthial – “false flower” – composite flower or capitulum
• pseudobasifixed – (of an anther) Connected to the filament of the stamen by connective tissue which extends in a tube around the filament tip. See also basifixed and dorsifixed.
• pseudobulb is a thickened, bulb-like internode in orchids, but not an actual bulb.
• pseudocarp – An aggregation of achenes embedded in an accessory fleshy receptacle, as in Fragaria. 
• pseudodrupe – Two-four loculed nut surrounded by an accessory fleshy involucre, as in Juglans. 
• pseudostipule – An enlarged, persistent axillary bud scale that resembles a stipule; ie Bignoniaceae.
• pseudoverticillate – Having the appearance of being whorled (verticillate), without actually being so.
• psilate – of pollen – lacking ornamentation. 
• puberulent – Also puberulous. Covered with minute soft erect hairs, diminutive of pubescent, similar but with very short hairs instead of short. 
• pubescent – Downy; covered with short, soft hairs, especially erect hairs.
• pulverulent – Having powdery or crumbly particles as if pulverized.
• pulviniform – Pulvinar; cushiony; pillowy; pad-like. In botany, cushion-shaped.
• pulvinus – pulvinate – a swelling at either end of a petiole of a leaf or petiolule of a leaflet, e.g. in Fabaceae, that permits leaf movement.
• punctate – (from Latin puncta= puncture or prick-mark) marked with an indefinite number of dots, or with similarly small items such as translucent glands or tiny hollows.
• punctiform – Dot-like or in the shape of a prick-mark.
• pungent – Having a sharp, hard point.
• pustule – A blister-like swelling.
• pustulate – Having pustules.
• pyramidal – (of a growth habit) Conical or pyramid-shaped. Most familiar in some coniferous trees, especially species adapted to snowy climates
• pyrene – 1. The stone of a drupe, consisting of the seed surrounded by the hardened endocarp.  2. The fleshy fruit with each seed surrounded by a bony endocarp, as in Ilex.
• pyriform – Pear-shaped; a term for solid shapes that are roughly conical in shape, broadest one end and narrowest at the other. As a rule the distal third of their length is the broadest, and they are narrowest near the proximal end, the base, where the stalk, if any, attaches.
• pyrophile – Plants which need fire for their reproduction.
• pyrophyte – Plants which have adapted to tolerate fire.

Q

• quincuncial – in aestivation – with 5 parts where 2 petals or sepals are outside all others, 2 are inside all others and the 5^th is outside on one margin and inside on the other.
• (q.v.) – q.v. (quod vide) used to tell readers to look in another place in the same book for a piece of information; specific to botany means undivided, whole; in reference to a Family that contains more component genus ie lumped instead of split. See also s.s.

R

• r – strategists – species whose populations are governed by their maximum reproductive capacity, r. They are generally capable of reproduction at a relatively young age, however, many offspring die before they reach reproductive age. They are often referred to as opportunistic species because they typically have a very low level of specialization, in that they can survive in less than ideal environmental conditions.
• raceme – adj. Racemose – An indeterminate inflorescence in which the main axis produces a series of flowers on lateral stalks, the oldest at the base and the youngest at the top. Compare spike. Racemules are small racemes or the ultimate raceme unit.  Also racemiform is raceme like. 
• racemose corymb – a raceme in which the pedicels of the lower flowers are longer than those of the upper ones so that the appearance of the inflorescence overall is that of a flat flower
• rachilla (rhachilla) – the axis of a grass spikelet, above the glumes.
• rachis pl. rachises or rachides – The axis of an inflorescence or a pinnate leaf; for example ferns; secondary rachis is the axis of a pinna in a bipinnate leaf distal to and including the lowermost pedicel attachment.
• radial – With structures radiating from a central point as spokes on a wheel 
• radiate – (of daisies, of a capitulum) With ray florets surrounding disc florets.
• radical – Springing from the root; clustered at base of stem.
• radicle – The part of an embryo giving rise to the root system of a plant, the first organ to appear. Compare plumule.
• ramet – An individual member of a clone.
• ramicaul – a single-leafed stem, as in Pleurothallis orchids.
• ramified – ramification is the divergence of the stem and limbs of a plant into smaller ones, i.e. trunk into branches, branches into increasingly smaller branches 
• ramiflorus –  Of a plant: having flowers or fruit borne directly on (older or larger) branches. Also: (of a flower or fruit) growing from a branch; designating or relating to this habit of growth.
• raphe – longitudinal ridge on the side of ovules or seeds
• raphides – any of numerous needle-shaped crystals, usually of calcium oxalate, that occur in many plant cells as a metabolic product.
• ray – 1.  zygomorphic (ligulate) flowers in a radiate flowerhead, that is, ray-florets/flowers, for example Asteraceae.  2.  each of the branches of an umbel.
• receptacle – the axis of a flower, in other words, floral axis; torus; for example in Asteraceae, the floral base or receptacle is the expanded tip of the peduncle on which the flowers are inserted. 
• receptacular – pertaining to or growing on the receptacle
• recurved – bent or curved backwards or downwards.
• reduplicate – folded outwards, or with the two abaxial surfaces together.
• reflexed – bent sharply back or down.
• regma – a capsule with two or more lobes and as many one-seeded, two-valved cells, which separate at maturity, splitting elastically from the persistent axis (carpophore), as in Geranium. It is a schizocarp.
• reniform – Kidney-shaped. Also subreniform almost kidney shape.
• replum – fruits – the remain after framework of some pods that remain after the valves drop off, a result of persistent false septa
• resin – a solid or highly viscous substance secreted for their protective benefits in response to injury. The resin protects the plant from insects and pathogens.
• resupinate – 1.  In botany, describing leaves or flowers that are in an inverted position because the petiole or pedicel, respectively, is twisted 180 degrees. compare: #hyper-resupinate  2.  In lichenology, referring to either having or being a fruiting body that lies flat on the substrate, with the hymenium either over the whole surface or at the periphery.
• reticulate – reticulodromous.  Forming a network (or reticulum), often used in venation where veins join one another at more than one point.
• retincacula – also retinaculum – A small gland or process to which bodies are attached; as, the glandular retinacula to which the pollinia of orchids are attached, or the hooks which support the seeds in many acanthaceous plants.
• retrorse – Bent backwards or downwards. Compare antrorse.
• retuse – Having a blunt (obtuse) and slightly notched apex.
• revolute – rolled under (downwards or backwards), for example when the edges of leaves are rolled under towards the midrib. Compare involute.
• rhizine – The “root” or “trunk” projection of a foliose lichen that attaches the lichen to the substrate (what the lichen is growing on)
• rhizodermis – the root epidermis, the outermost primary cell layer of the root
• rhizoids – a short, thin filament found in fungi and in certain plants and sponges that anchors the growing (vegetative) body of the organism to a substratum and that is capable of absorbing nutrients. In fungi, the rhizoid is found in the thallus and resembles a root.
• rhizome – a perennial underground stem usually growing horizontally. See also stolon. Abbreviation: rhiz.
• rhizomatous – adj. a plant whose above ground stem is derived from a below ground stem (rhizome). cf. arhizomatous (arhizomatic)
• rhizosphere – the below-ground surface of plants and adjacent soil as a habitat for microorganisms.
• rhytidome – the dead region of the bark that lies outside the periderm.
• rhombic – like a rhombus: an oblique figure with four equal sides. Compare trapeziform, trullate.
• rhomboid – a four-sided figure with opposite sides parallel but with adjacent sides an unequal length (like an oblique rectangle); see also rhombic.
• rhomboidal – a shape, for instance of a leaf, that is roughly diamond-shaped with length equal to width.
• rimose – with many cracks, as in the surface of a crustose areolate lichen.
• root – a unit of a plant’s axial system which is usually underground, does not bear leaves, tends to grow downwards, and is typically derived from the radicle of the embryo.
• root hairs – outgrowths of the outermost layer of cells just behind the root tips, water-absorbing organs.
• root microbiome – the dynamic community of microorganisms associated with plant roots.
• root nodules –  found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria
• rootstock – 1. the part of a budded or grafted plant which supplies the root system, also simply called a stock. 2.  plants selected to produce a root system with some specific attribute, e.g. a virus-free rootstock.
• rosaceous – with 5 or more wide spreading roundish petals like a rose eg Rosa.
• rosette – Adj: rosulate. When parts are not whorled or opposite but appear so, due to the contractions of internodes, e.g. the petals in a double rose or a basal cluster of leaves (usually close to the ground) in some plants.
• rostellate – possessing a beak (rostellum). Synonym of rostrate
• rostrate – having a beak resembling that of a bird.
• rotate – circular and flattened, wide spreading; for example a corolla with a very short tube and wide spreading wheel like lobes (for instance some Solanaceae).
• RuBisCO – An enzyme found in chloroplasts involved in fixing atmospheric carbon dioxide during photosynthesis and in oxygenation of the resulting compound during photorespiration.
• ruderal – a plant that colonizes or occupies disturbed waste ground. See also weed.
• rudiment – In the structure of a plant, an item that is at best hardly functional, either because it is immature and has not yet completed its development (such as a leaf still incompletely formed inside a bud), or because its role in the organism’s morphology cannot be completed and therefore is futile (such as the leaf rudiment at the tip of a phyllode, that will be shed while immature, because the leaf function will be taken over by the phyllode). Compare cataphyll, vestige.
• rudimentary – Being of the nature of a rudiment; at most barely functional because incompletely developed; begun, but far from completed, either temporarily or permanently. Compare vestigial.
• rufus – reddish – brown color
• rugose – Also rugae – wrinkled, either covered with wrinkles, or crumpled like a wrinkled leaf, either as a stiffening structure, or in response to disease or insect damage.
• rugulose – finely wrinkled.
• ruminate – (usually applied to endosperm) Irregularly grooved or ridged; appearing chewed, e.g. the endosperm in certain members of Myristicaceae.
• runcinate – Sharply pinnatifid or cleft, with the segments directed downward.
• rupicolous – rupestral, saxicolous, growing on or among rocks. Compare epilithic and lithophytic.

S

• saccate – Pouched or shaped like a sack.
• sagittate – Shaped like the head of an arrow; narrow and pointed but gradually enlarged at the base into two straight lobes directed downwards; may refer only to the base of a leaf. Compare hastate.
• salverform – Trumpet-shaped; having a long, slender tube and a flat, abruptly expanded limb.
• samara – A dry, indehiscent fruit with its wall expanded into a wing, e.g. in the genus Acer. A samaroid is adj – samara like, subsamaroid is almost a samaroid.  
• samaracetum – An aggregation of samaras, as in Liriodendron.
• samphire – A common name given to various edible coastal plants, such as Salicornia spp. (Amaranthaceae), Crithmum maritimum (Apiaceae) and Limbarda crithmoides (Asteraceae).
• sanguine – from Latin sanguineus, blood-coloured: crimson; the colour of blood.
• saponin – any of various mostly toxic glycosides that occur in plants (such as soapwort or soapbark) and are characterized by the property of producing a soapy lather making it useful as a surfactant, some natural saponins are harvested for use as surfactants (detergents).
• saprophyte – adj. Saprophytic – A plant, or loosely speaking, a fungus or similar organism, deriving its nourishment from decaying organic matter such as dead wood or humus, and usually lacking chlorophyll. Compare parasite, saprotroph and epiphyte.
• saprotroph – adj. saprotrophic – An organism deriving its nourishment from decaying organic matter. Contrast parasite and epiphyte.
• sarcotesta – outer, usually softer fleshy part of a testa in various seeds (esp cycads).
• sarment – A long, slender, prostrate stolon, commonly called a runner.
• sarmentose – Reproducing by sarments; strawberry plants are the most familiar example.
• saxicolous – Growing on stone, like some lichens.
• scabrous – Also scabrid. Rough to the touch, with short hard protrusions or hairs.
• scalariform – Ladder-like in structure or appearance.
• scale – 1.  A reduced or rudimentary leaf, for example around a dormant bud.  2.  A flattened epidermal outgrowth, such as those commonly found on the leaves and rhizomes of ferns.
• scandent – Climbing, by whatever means. 
• scape – adj. scapose – A stem-like flowering stalk of a plant with radical leaves, a leafless flower stalk with leaves only at the base.  A long naked or nearly naked peduncle often growing directly from the rhizome or bulb.
• scapose/scapiflorous/scapigerous – Having a scape.
• scarious – Dry and membranous.
• schizocarp – A dry fruit formed from more than one carpel but breaking apart into individual carpels (mericarps) when ripe. There are many types of schizcarops.
• schizocarpic berries – Separating berries which have a fleshy pericarp, as in Phytolacca.
• schizocarpic follicles – Separating follicles which are dry, dehiscent (splits at maturity) fruits derived from one carpel, splitting along one suture, as in Apocynaceae.  Also called follicetum. 
• schizocarpic nutlets – Separating nutlets which are dry,indehiscent (do not split at maturity) 4-parted fruits with a hard pericarp around a gynobasic style, as in the Boraginaceae and Lamiaceae. Aka cenobium
• schizogenous – of intercellular space in plants formed by the splitting of the common wall of contiguous cells.  Often applied to secretory cells. 
• scion – The aerial part of a graft combination, induced by various means to unite with a compatible understock or rootstock.
• sclereid – A cell with a thick, lignified, cell wall that is shorter than a fiber cell and dies soon after the thickening of its cell wall.
• sclerenchyma –  A strengthening or supporting tissue composed of sclereids or a mix of sclereids & fibers.
• sclerophyll – sclerophyllous – A plant with hard, stiff leaves; structures stiffened with thick-walled cells.
• scorpioid cyme – Branching alternately on one side and then the other; a type of monochasium on which the successive axes arise alternately in respect to the preceding one.  Synonym cincinni or cincinnus. Compare helicoid cyme.
• scrobiculate – Having very small pits.
• scrubland – Dense vegetation dominated by shrubs.
• scurf – adj. scurfy.  Minute, loose, membranous scale like particles on the surface of some plant parts, such as leaves.  
• secondary metabolite – Chemicals produced by a plant that do not have a role in so-called primary functions such as growth, development, photosynthesis, reproduction, etc.
• secondary species – In lichens, a “species” taxon of lichen reproducing only by vegetative means, whose components reproduce mainly by sexual means – cf. primary species.
• secretory tissue – tissues concerned with the secretion of gums, resins, oils and other substances in plants.
• secund – Having all the parts grouped on one side or turned to one side (applied to inflorescences).
• segment – A part or subdivision of an organ, e.g. a petal is a segment of the corolla. A term sometimes used when the sepals and petals are indistinguishable.
• self-pollination – (also selfing) The acceptance by stigmas of pollen from the same flower or from flowers on the same plant, which means they are self-compatible.
• semaphyll – A structure such as a bract or sepal (if the remainder of the perianth is inconspicuous) which has become modified to attract pollinators.
• semelparity – When a plant flowers once then dies.
• semicarpous – nearly apocarpous, barely fused carpels 
• seminal roots – Any of the adventitious roots that grow from the base of the stem during early seedling growth and take over the functions of the radicle.
• semiterete – Rounded on one side but flat on the other. See also terete.
• sensitive – A descriptive term for stigmas that, in response to touch, close the two lobes of the stigma together, ending the receptivity of the stigma, at least for the time that the lobes are closed together. Mimulus is perhaps the best-known example.
• sensu lato – (of a plant group) In a broad sense.
• sensu stricto – (of a plant group) In a narrow sense.
• sepal – In a flower, one of the segments or divisions of the outer whorl of non-fertile parts surrounding the fertile organs; usually green. Compare petal.
• septicidal – A capsule that dehisces (splits at maturity) longitudinally through the septa, along partitions between loculi. As in Penstemon.  Compare loculicidal. 
• septifragal – dehiscing by breaking away of the valves from the septa
• septum – pl. septa – A partition, e.g. the membranous wall separating the two valves of a seed pod.
• seriate – Arranged in rows.  biseriate – arranged in 2 rows, triseriate arranged in 3 rows etc.
• sericeous – Silky with dense appressed soft silky hairs; similar to strigose but soft instead of stiff hairs.
• serrate – Toothed with asymmetrical teeth pointing forward; like the cutting edge of a saw.
• serrulate – Finely serrate.
• sessile – Attached without a stalk, e.g. of a leaf without a petiole or a stigma, when the style is absent.
• seta – pl. setae; adj. setose, setaceous – A bristle or stiff hair (in Bryophytes, the stalk of the sporophyte). A terminal seta is an appendage to the tip of an organ, e.g. the primary rachis of a bipinnate leaf in Acacia.
• sheath – A tubular or rolled part of an organ, e.g. the lower part of the leaf in most grasses.
• shoot – The aerial part of a plant; a stem and all of its dependent parts (leaves, flowers, etc.).
• shrublet – dwarf shrub
• sigmoid – Shaped like the letter ‘S’.
• silicle – A dry, dehiscent (splits at maturity) fruit derived from two or more carpels that dehisce along two sutures and which has a persistent partition after dehiscence and is as broad as, or broader, than long.
• silicula – a stout siliqua (in contrast to a siliqua, not more than twice as long as wide).
• silique –  dry, dehiscent fruit (in contrast to a silicula,more than twice as long as wide) formed from a superior ovary of two carpels, with two parietal placentas and divided into two loculi by a ‘false’ septum.
• silky – densely covered with fine, soft, straight, appressed hairs, with a lustrous sheen, satiny to the touch.
• simple – Undivided or unsegmented, e.g. a leaf not divided into leaflets (note, however, that a simple leaf may still be entire, toothed or lobed) or an unbranched hair or inflorescence.
• sinuate or sinuose – Having deep, wave-like depressions along margins, but mostly flat. Compare undulate.
• Sinus – A notch or depression between two lobes or teeth in the margin of an organ.
• s.l. – sensu lato – in the broad sense refers to more broadly described families.     
• solitary – Single, of flowers that grow one plant per year, one in each axil, or widely separated on the plant; not grouped in an inflorescence.
• soralia – In a lichen, the structure that bears soredium for non sexual reproduction.
• soredium – pl. soredia – In a lichen, a small groups of algal cells surrounded by fungal filaments that form in soralia, which break off and grow new lichens without sexual reproduction after being dispersed by wind. Compare to an isidium, which breaks off and is dispersed by mechanical means.
• sorus – pl. sori A cluster of sporangia. Sori typically occur in ferns, some Algae and some fungi. In many fern species the sorus is covered by a protective indusium
• spadix – A spicate (spike-like) inflorescence with the flowers crowded densely, even solidly, around a stout, often succulent axis. Particularly typical of the family Araceae
• spathe adj. spathaceous or spatheate – A large bract en-sheathing an inflorescence. Traditionally any broad, flat blade.  Without a spathe: espatheate. 
• spatheolate – a small bract en-sheathing an individual flower.
• spathulate  or spatulate – Spoon-shaped; broad at the tip with a narrowed projection extending to the base.
• spica adj. spicate or spiciform – Another name for a spike.
• spicule – adj spiculate – A small sharp crystal, such as one of silicate or calcium carbonate supporting the soft tissue of certain plants and invertebrates.
• spike – adj. spicate – An unbranched, indeterminate inflorescence in which the flowers are without stalks. Compare raceme.
• spikelet – A subunit of a spike inflorescence, especially in grasses, sedges and some other monocotyledons, consisting of one to many flowers and associated bracts or glumes.
• spine – adj. Spinose or spiniferous  – A stiff, sharp structure formed by the modification of a plant organ that contains vascular tissue, e.g. a lateral branch or a stipule; includes thorns. Also spinulose is small spinose. 
• spinescent – Ending in a spine; modified to form a spine.
• spiral – Of arrangement, when plant parts are arranged in a succession of curves like the thread of a screw, or coiled in a cylindrical or conical manner.
• spiraperturate –  pollen grains of Berberis, Eriocaulon spp with spiral apertures or with somewhat aperturoid weak streaks which probably derived from colpi, rugae, or sulci etc. S
• spirocyclic –  also known as ‘Hemicyclic’. having flowering parts such as stamens and carpels are arranged spirally in Ranunculaceae. The arrangement of Spirocyclic flower is spiral and whorled.
• spirodistichous – referring to a type of leaf arrangement in which the leaves are initially distichous but later appear spirally arranged. 
• splash-cup (sporangia) – A cup-like structure in fungi such as Nidulariaceae and in cryptogams such as some mosses. The cups function in spore dispersal, in which the energy of raindrops falling into the cup causes the water to splash back out carrying the spores.
• splitters – taxonomists who prefer to split genera up into less variable smaller families (which make identification and family descriptions more specific and useful) than lump them together in more variable families. 
• sporangium (sporangia) – A structure in which spores are formed and where mature spores are released
• sporangiophore –An organ bearing sporangia, e.g. the cones of Equisetum.
• spore – A haploid propagule, produced by meiosis in diploid cells of a sporophyte that can germinate to produce a multicellular gametophyte.
• sporocarp – A fruiting body containing spores.
• sporophyll – In pteridophytes, a modified leaf that bears a sporangium or sporangia.
• Sporophyte – The haploid multicellular phase in the alternation of generations of plants and algae that produces the spores. Compare gametophyte.
• sport – A naturally occurring variant of a species, not usually present in a population or group of plants; a plant that has spontaneously mutated so that it differs from its parent plant.
• spreading – Extending horizontally (in branches). Standing out at right angles to an axis (leaves or hairs).
• spur – 1.  a short shoot.  2.  a conical or tubular outgrowth from the base of a perianth segment, often containing nectar.
• squamule – (plural squamules, squamulae) small scales; In lichens, squamules are overlapping plate-like forms, sometimes overlapping so much as to become leaf-like, but which lack a lower cortex, unlike the leafy forms of foliose lichens – adjective: squamulose
• squamulose – Covered with small scales (squamules). In lichens, being composed of squamules.
• squarrose – Having tips of leaves, stems, etc. radiating or projecting outwards, e.g. in the moss Rhytidiadelphus squarrosus.
•  s.s. – sensu stricto –in the strict sense refers to families more broken down and strictly defined.
• stachysporous – sporangia borne directly on a more or less modified stem
• stalk – The supporting structure of an organ, usually narrower in diameter than the organ itself.
• stamen – adj. staminate – The male organ of a flower, consisting (usually) of a stalk called the filament and a pollen-bearing head called the anther.
• staminate flower Also male flower. – A flower with stamens but no pistil.
• staminode – adj: staminodal.  A sterile stamen, often rudimentary, sometimes petal-like.
• staminophore – A structure, around the apex of eucalypt, myrtaceae hypanthia, that supports the stamens.
• standard – The large posterior petal of pea-flowers.
• standard specimen – A representative specimen of a cultivar or other taxon which demonstrates how the name of that taxon should be used.
• stele – the primary vascular system (including phloem, xylem, and ground tissue) of plant stems and roots.
• stellate – adj: stellately as in stellately spreading.  Star-shaped.  Star shaped hairs common in Malvaceae.
• stem – The plant axis, either aerial or subterranean, which bears nodes, leaves, branches and flowers.
• stenospermocarpy – The development or production of fruit that is seedless or has minute seeds because of the abortion of seed development. Compare parthenocarpy.
• stigma – The pollen-receptive surface of a carpel or group of fused carpels, usually sticky; usually a point or small head at the summit of the style.
• stipe – Generally a small stalk or stalk-like structure. The stalk of a frond of a fern; the stalk supporting the pileus of a mushroom; the stalk of a seaweed (ie kelp); the stalk-like support of a gynoecium or a carpel
• stipella – stipel; pl. stipellae – One of two small secondary stipules at the base of leaflets in some species.
• stipitate – stalked; borne on a stipe; of an ovary, borne on a gynophore.
• stipulate – Bearing stipules.
• stipule – A small appendage at the bases of leaves in many dicotyledons.
• stipel – adj: stipellate . A small stipule at the base of leaflets and not at the base of the leaf as is the case with a true stipule.  Stipels are only found in compound leaves.
• stolon – Also runner.  A slender, prostrate or trailing stem, producing roots and sometimes erect shoots at its nodes. See also rhizome.
• stoloniferous – Having stolons.
• stoma – pl. stomata – A pore or small hole in the surface of a leaf (or other aerial organ) allowing the exchange of gases between tissues and the atmosphere.
• stone cell – a sclereid cell, such as the cells that form the tissue of nut shells and the stones of drupes.
• striate – Striped with parallel, longitudinal lines or ridges.
• strigose – Covered with appressed, straight, rigid, bristle-like hairs; the appressed equivalent of hispid.  Finely strigose is strigulose. 
• strobilus – pl. strobili adj: strobiloid or strobiliform.  A cone-like structure consisting of sporophylls (e.g. conifers and club mosses) or sporangiophores (e.g. in Equisetopsida) borne close together on an axis.
• style – An elongated part of a carpel or a group of fused carpels between the ovary and the stigma.
• stylodium – An elongate stigma that resembles a style; a false style, found in the Poaceae and Asteraceae.
• stylopodium – A swelling on top of the ovary, at the base of the styles, found in flowers of the Apiaceae.
• stylulus – The elongated apex of a free carpel which functions like the style of a syncarpous ovary, allowing pollen tubes from its stigma to enter the locule of only that carpel.
• subcoriaceous – Slightly leathery or coriaceous.
• subentire – almost entire, slightly indented.
• suberose – relating to or resembling cork, corky. 
• subglobose – Inflated, but less than spherical. See also globose.
• subpyramidal – shrubs, almost pyramidal in shape
• subshrub – subshrubs. Also undershrub. A small shrub which may have partially herbaceous stems, but generally a woody plant less than 1 meter (3.3 ft) high.
• subtend – To stand beneath or close to, as in a bract at the base of a flower.
• subterranean – below the ground
• subquadrangular – Not quite square. Compare quadrangular.
• subturgid – slightly turgid
• subulate – Narrow and tapering gradually to a fine point.
• subvaginate – less than sheathed but not quite unsheathed. Vaginate is synonym of sheathed. 
• succulent – 1.  Juicy or fleshy.  2.  A plant with a fleshy habit.
• succession and successional advancement – the natural progression from one ecosystem type to another. There are typically a number of different stages, each generally with increasing structural complexity.
• sucker – A shoot of more or less subterranean origin; an erect shoot originating from a bud on a root or a rhizome, sometimes at some distance from the stem of the plant.
• syconium – A syncarp (multiple fruit) with the achenes borne on the inside of a hollowed-out, compound, fleshy receptacle or peduncle, as in Ficus.
• suffrutex – pl. suffrutices – A subshrub or undershrub.
• sulcate – Furrowed; grooved. May be single (monosulcate), two (bisulcate) or many (polysulcate). Also sulcus, sulci.
• superficial – On the surface.
• superior – Of an ovary, borne above the level of attachment of the other floral parts, or above the base of a hypanthium. Contrast inferior and half-inferior.
• suspended – Of an ovule, when attached slightly below the summit of the ovary. Compare pendulous.
• suture – A junction or seam of union. See fissure and commissure.
• sward – Extensive, more or less even cover of a surface, e.g. a lawn grass. Compare tussock.
• switch plants – plants with photosynthetic functions transferred from leaves to other organs, usually stems.
• sympatric – Having more or less similar or overlapping ranges of distribution.
• sympodial – A mode of growth in which the main axis is repeatedly terminated and replaced with a lateral branch. Examples occur in Combretaceae, including the genera Terminalia and Combretum. cf. monopodial
• syconium – also syncarp A hollow infructescence containing multiple fruit, such as that of a fig; formed from 2+ carpels of one flower or the aggregated fruits of several flowers, ie an entire inflorescence.
• syn– Also sym-. A prefix meaning “with, together”.
• symmetrical –  Capable of being divided into at least two equal, mirror-image halves (e.g. zygomorphic) or having rotational symmetry (e.g. regular or actinomorphic). Compare irregular and asymmetrical.
• sympetalous – Having united (connate or fused) petals, not free (#apopetalous)
• synandrium – an androecium with fused anthers
• synangium – A fused aggregate of sporangia, e.g. in the trilocular sporangia of the whisk fern Psilotum.
• synanthous – A type of growth in which new leaves and flowers appear and die back at the same time. See also hysteranthous and proteranthous.
• synapomorphy – a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants.
• synaptospermy – The dispersal of diaspores as units, where each bears more than one seed, for example where each diaspore comprises an entire inflorescence, as in Brunsvigia or multi-seeded fruit as in Tribulus zeyheri. Ephemeral synaptospermy is the term for when the diaspores split into units containing fewer or single seeds each, as in most tumbleweeds. True synaptospermy is when the diaspore generally remains entire until germination, as commonly happens in species of Grielum.
• syncarpous – (of a gynoecium) Composed of united carpels.
• synflorescence – A flower cluster segregated from any other flowers on the same plant, together with the stems and bracts (reduced leaves) associated with it. Certain plants produce inflorescences, whereas others produce only solitary flowers. 
• synonym – An outdated or ‘alternative’ name for the same taxon.
• synoecious – A synonym of bisexual.
• synovarious – the fusion of ovaries and carpels but the style and stigmas remain separate. 
• synsepalum – fused sepals 
• synstylous – the fusion of styles but the ovary carpels remain separate. Compare synstylovarious.  
• synstylovarious – the fusion of styles and ovary. Compare synstylous.
• syntepalous – Having fused tepals. See also sympetalous (having fused petals).

T

• tapetum – a specialized layer of nutritive cells found within the anther of flowering plants between the sporangenous tissue and the anther wall. Tapetum is important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat.
• taproot – The primary descending root of a plant with a single dominant root axis.
• tartareous – Having a surface that is course, thick, rough, and crumbling.
• tegmen – The inner layer of the testa (seed coat). It develops from the inner integument of the ovule.
• tendril – Any slender organ modified from a stem, leaf, leaflet, or stipule and used to cling to an object.
• tenuinucellate – ovules with no nucellar tissue separating embryo sac and epidermis 
• tepal – A segment of a perianth, either sepal or petal; usually used when all perianth segments are indistinguishable in appearance.
• Tepuis – A tepui, or tepuy is a table-top mountain or mesa found in the Guiana Highlands of South America, especially Venezuela and western Guyana. The word tepui means “house of the gods” in the native language of the Pemon, the indigenous people who inhabit the Gran Sabana.
• terete – Also semiterete. Circular in cross-section; more or less cylindrical without grooves or ridges.
• terminal – Situated at the tip or apex.
• ternate – In groups of three; of leaves, arranged in whorls of three; of a single leaf, having the leaflets arranged in groups of three.
• terpene – terpenes  are a large and diverse class of organic compounds produced by a variety of plants but especially conifers (and some insects). They often have a strong odor and seem to protect the plants by deterring herbivores and attracting predators and parasites of herbivores.
• terrestrial – Of or on the ground; of a habitat, on land as opposed to in water (aquatic), on rocks (lithophytic), or on other plants (epiphytic).
• testa – The seed coat.
• tetracytic – Refers to stomata that possess one or more pairs of lateral subsidiary cells oriented parallel with the guard cells. Tetracytic. Refers to stomata that possess both lateral and polar subsidiary cells. Terms applied to stomata in which development is well documented.
• tetrad – A group of four; usually used to refer to four pollen grains which remain fused through maturity
• tetragonal – Square; having four corners; four-angled (cross-sections of stem Lamiaceae herbs).
• tetradynamous – a flower has six stamens, two outer shorter than the inner four
• teratological – the science of animal or plant monstrosities that deals with malformations or monstrous or abnormal growths in the animal or plant kingdoms.
• tetramerous – In four parts, particularly with respect to flowers; four parts in each whorl. See also trimerous and pentamerous.
• tetraploid – Organisms that possess 4 times more chromosomes than a haploid cell. tetraploid. nucleus, cell or organism that has four copies of the normal haploid chromosome set.
• tetraspore – The asexual spore of red algae. It is so named because each sporangium produces just four spores. See Rhodophyceae.
• thallus – the “vegetative” part (part other than sexual fruitbodies) of a lichen that has both the fungus (mycobiont) and photobiont; plural thalli
• theca – One of the usually two synangia in which pollen is produced in flowering plants. It consists of two fused sporangia known as pollen sacs. The wall between the pollen sacs disintegrates before dehiscence, which is usually by a common slit. Pl: thecae  
• thorn – A sharp, stiff point, usually a modified stem, that cannot be detached without tearing the subtending tissue; a spine. Compare prickle.
• throat – The opening of a corolla or perianth.
• thyrse – A branched inflorescence in which the main axis is indeterminate (racemose) and the lateral branches determinate (cymose).
• tomentose or tomentum – A dense covering of short, matted hairs, similar to woolly but shorter hairs; tomentulose is slightly tomentose. Tomentose is often used as a general term for bearing an indumentum, but this is not a recommended use.
• toothed – Having a more or less regularly incised margin.
• trapeziform – 1.  Like a trapezium (a four-sided figure with two parallel sides of unequal length). 2.  Like a trapezoid (a four-sided figure, or quadrilateral, with neither pair of sides equal); sometimes used erroneously as a synonym for rhombic.
• treelet – An erect, single-stemmed, woody plant less than 5 centimeters dbh and more than 2 meters tall; differences between treelets and unbranched shrubs or trees are sometimes unclear.
• triad – A group of three.
• triangular – Planar and with 3 sides.
• tribrachiate – the style divides into three petal-like (petaloid) style branches (sometimes also referred to as ‘stylodia’), almost to the base of the style.
• trichome – In non-filamentous plants, any hair-like outgrowth from the epidermis, e.g. a hair or bristle; sometimes restricted to unbranched epidermal outgrowths.
• tridentate – used to describe either having 3 teeth, or having teeth that are themselves bidentate. 
• trifid – Split into three parts. See also bifid.
• trifoliate – A compound leaf of three leaflets; for example, a clover leaf.
• trifoliolate – See trifoliate.
• trigonous – Triangular in cross-section and obtusely angled. Compare triquetrous.
• trilacunar – The node with a single gap and a single trace to a leaf is known as unilacunar; the node with three gaps and three traces to a leaf (one median and two lateral) is known as trilacunar; and the node with several to many gaps and traces to a leaf is known as multi-lacunar.
• trimerous – In 3 parts, particularly flowers with 3 parts in each whorl. See tetramerous and pentamerous.
• Trine – 3 fold; having 3 of something. 
• trinerved – Having three nerves or veins.
• tripinnate – having bipinnate leaflets that are themselves pinnately divided. 
• triplinerved – (of leaves) Having three main nerves with the lateral nerves arising from the midnerve above the base of the leaf.
• triploid – applied to a cell that has three sets (3n) of chromosomes in its nucleus, or to an organism composed of such cells (as opposed e.g. to haploid (n) or diploid (2n) cells or organisms). See also polyploid.
• triquetrous – More or less triangular in cross-section, but acutely angled (with 3 distinct longitudinal ridges). Compare trigonous.
• tristichous – Arranged in 3 rows 
• tristylous – also tristyly condition in which three different style lengths and corresponding stamen lengths are found in the same species, the flower morphs are short styled, intermediate styled, and long styled. 
• trivalve – Divided into three valves. Also trivalvar. See also bivalve.
• trophophyll – A vegetative, nutrient-producing leaf or microphyll whose primary function is photosynthesis. It is not specialized or modified for some other function. Compare sporophyll.
• trullate – Ovate but angled, as with a bricklayer’s trowel; inversely kite-shaped. Compare rhombic.
• truncate – Cut off squarely; having an abruptly transverse end.
• trunk – The upright, large and typically woody main stem of a tree.
• truss – A compact cluster of flowers or fruits arising from one centre; evident in many rhododendrons.
• tryma – Two-four loculed nuts surrounded by a dehiscent (splitting at maturity) involucre at maturity, as in most species of Carya. (accessory structure Involucre)
• trymarium – schizocarp of  trymas released at maturity by splitting accessory perianth
• tuber – Any of many types of specialized vegetative underground storage organs. They accumulate food, water, or in protection from death by fire, drought, or other hard times. Tubers generally are well differentiated from other plant organs; for example, informally a carrot is not generally regarded as a tuber, but simply a swollen root. In this they differ from the tuber of a sweet potato, which has no special root-like function. Similarly, corms are not generally regarded as tubers, even though they are underground storage stems. Tubers store food for the plant, and also have important roles in vegetative reproduction. They generally are of two main types: stem tubers formed by the swelling of an underground stem growing from a root, or from structures such as underground stolons. Stem tubers generally produce propagative buds at their stem nodes, forming a seasonal perennating organ, e.g. a potato. The main other class is the root tuber, also called tuberoid. They differ from stem tubers in features such as that they do not form nodes.
• tubercle – A small wart-like outgrowth or protuberance of tissue.
• tuberculate or tubercled – Covered in tubercles. See tubercle or warty.
• tuberoid – Alternative name for underground storage organ formed by swelling of a root; occurs in orchids.
• tuberous – Resembling a tuber or producing tubers.
• tubular – Having the form of a tube or cylinder.
• tufted – Densely fasciculate at the tip.
• tunic – The outer covering of some bulbs and corms.
• tunicate – (of bulbs) Consisting of concentric coats.
• turbinate – Shaped like a spinning top or beetroot.
• turgid – Swollen with liquid; bloated; firm. Compare flaccid.  Adj: turgescent 
• tussock – A dense tuft of vegetation, usually well separated from neighboring tussocks, for example in some grasses. Compare sward.
• two-ranked – Having leaves arranged in 2 rows in the same plane, on opposite sides. See distichous.

U

• umbel – adj umbellate – racemose inflorescence in which all the individual flower stalks arise in a cluster at the top of the peduncle and are of about equal length; in a simple umbel, each stalk is unbranched and bears only one flower. A cymose umbel looks similar to an ordinary umbel but its flowers open centrifugally.  The secondary umbels of compound umbels are known as umbellules or umbellets.
• umbelliform – a compressed cyme that resembles an umbel. 
• umbonate – umbo – Having an umbo, with a conical or blunt projection arising from a flatter surface, as on the top of a mushroom or in the scale of a pine cone.
• unciform – Hook-shaped.
• uncinate – Having a hook at the apex.
• undershrub – A low shrub, often with flowering branches that die off in winter. Compare subshrub.
• undulate – Wavy and not flat. Compare sinuate.
• uniflor – Having a single flower (uniflory). Compare pauciflor (few) and pluriflor (many).
• unifoliate  – having a single leaf or leaflike part | 
• unilocular – Having one loculus or chamber, e.g. the ovary in the families Proteaceae and Fabaceae.
• uniserial – Arranged in a single row or series. Unbranched. Uniseriate.
• uniseriate – Arranged in a single row or series. Unbranched. Uniserial.
• unisexual –  Of one sex; bearing only male or only female reproductive organs, dioecious, dioicous. See Sexual reproduction in plants.
• unitegmic – (of an ovule) Covered by a single integument. See also bitegmic, having two integuments.
• urceolate – Shaped like an urn or pitcher, with a swollen middle and narrowing top. Examples include the pitchers of many species of the pitcher plant genera Sarracenia and Nepenthes.
• utricle – 1.  A small bladder; a membranous bladder-like sac from the ovary wall, thin pericarp, becomes more or less bladdery or inflated at maturity enclosing an ovary or fruit. 2.  In sedges, a fruit in which the fruit is loosely enclosed by a modified tubular bract, see perigynium.
• urticating – trichomes with hollow points that secrete an acrid fluid that cause burning and itching sensations. Eg: Euphorbiaceae, Urticaceae.

V

• vallecular canal – A resin canal coinciding with a longitudinal groove in the seeds of Asteraceae. A longitudinal cavity in the cortex of the stems of Equisetum, coinciding with a groove in the stem surface.
• valvate – (of sepals and petals in bud) Meeting edge-to-edge but not overlapping.
• valve – A portion of an organ that fragments or splits open, e.g. the teeth-like portions of a pericarp in a split (dehisced) capsule or pod when ripe.
• variant – A plant or group of plants showing some measure of difference from the characteristics associated with a particular taxon.
• variegated – Irregularly marked with blotches or patches of another colour.
• vascular – Referring to the conducting tissues (xylem and phloem) of vascular plants. Adj: vascularization 
• vascular bundle – A bundle of vascular tissue in the primary stems of vascular plants, consisting of specialized conducting cells for the transport of water (xylem) and assimilate (phloem).
• vasculum – A container used by botanists for collecting field specimens.
• vein – Also nerve. A strand of tissue, e.g. in the leaves of vascular plants. 
• veinlet – A small vein; the ultimate (visible) division of a vein.
• velamen – A spongy tissue covering the aerial roots of orchids and some other epiphytes.
• velutinous/Velvety – Densely covered with fine, short, soft, erect hairs.
• venation – The arrangement of veins in a leaf.
• ventral – adj: ventrally – From Latin venter, meaning “belly”. The opposite of dorsal. Partly because the term originally referred to animals rather than plants, usage in botany is arbitrary according to context and source. In general “ventral” refers to “the belly or lower part”, but in botanical usage such concepts are not always clearly defined and may be contradictory. For example: facing towards the axis (adaxial) in referring to a lateral organ of an erect plant
• ventrifix – attached on the inner side
• vernation – The arrangement of unexpanded leaves in a bud; the order in which leaves unfold from a bud.
• vernonioid – In the Compositae, style with sweeping hairs borne on abaxial surfaces of style branches.
• verruciform – Wart-like in form.
• verrucose – Having warts, synonym of tuberculose.
• verruculose – Minutely verrucose; minutely warty. 
• versatile – (of anthers) Swinging freely about the point of attachment to the filament.  Compare non-versatile, unable to swing freely at the point of attachment.
• verticillate – Arranged in one or more whorls, i.e. several similar parts arranged at the same point of the axis, e.g. leaf arrangement. Compare pseudoverticillate (appearing whorled or verticillate but not actually) and subverticillate almost verticillate but not quite. 
• verticillaster – pairs of opposite axillary, usually sessile, cymes, common in Lamiaceae; they appear whorled but are not.
• vesicular – (of hairs) Bladder-like; vesciculous, bearing such hairs.
• vessel – A capillary tube formed from a series of open-ended cells in the water-conducting tissue of a plant.
• vestigial – Reduced in form and function from the normal or ancestral condition.
• vexillary – in aestivation where a larger petal (i.e. the standard) overlaps other smaller petals, often seen in the Fabaceae family. 
• vilano – the whorl of sepals, another name for calyx
• villous – covered with long, soft, shaggy hairs, not entangled (then woolly).
• vine – 1.  Scandent plants climbing by means of trailing or twining stems or runners.  2.  Such a stem or runner. 3.  A member of the genus Vitis.
• virgate – Diminutive: virgulate – Wand-shaped, twiggy, especially referring to erect, straight stems. In mycology, referring to a pileus with radiating ribs or lines.
• viridiplantae – A clade of autotrophic organisms that includes the green algae, Charophyta and land plants, all of which have cellulose in their cell walls, chloroplasts derived from primary endosymbiosis with Cyanobacteria that contain chlorophylls a and b and lack phycobilins.
• viscous or viscid – Sticky; coated with a thick, resinous secretion.
• viviparous – 1.  Referring to seeds or fruits which germinate before being shed from the parent plant. 2. The development of plantlets on non-floral organs, e.g. leaves.
• volva – a cup-shaped structure that sheathes the base of the stalk of certain mushrooms. 

W

• warty – A surface covered with small round protuberances, especially in fruit, leaves, twigs and bark. See tuberculate.
• watershoot – An erect, strong-growing, or epicormic shoot developing from near the base of a shrub or tree, but distinct from a sucker.
• weed – 1.  Any plant growing where it is not wanted; commonly associated with disrupted habitats. See also ruderal.  2.  An unwanted plant which grows among agricultural crops.  3.  A naturalized, exotic, or ecologically “out-of-balance” indigenous species outside of the agricultural or garden context, which, as a result of invasion, adversely affects the survival or regeneration of indigenous species in natural or partly natural vegetation communities.[14]
• wild – Originating from a known wild or purely natural habitat (wilderness).
• whorl – A ring of organs borne at the same level on an axis (e.g. leaves, bracts, or floral parts).
• wing –  1.  A membranous expansion of a fruit or seed which aids in dispersal, for instance on pine seeds. 2.  A thin flange of tissue extending beyond the normal outline of a structure, e.g. on the column of some orchids, on stems, on petioles.  3.  One of the two lateral petals of a flower of subfamily Faboideae of family Fabaceae, located between the adaxial standard (banner) petal and the two abaxial keel petals.
• woolly – Very densely covered with long, more or less matted or intertwined hairs, resembling sheep wool, similar to tomentose but usually longer hairs.

X

• xerochastic – dehiscence were seeds are released by successive dehiscence of the locules.
• xeromorph – A plant with structural features (e.g. hard or succulent leaves) or functional adaptations that prevent water loss by evaporation; usually associated with arid habitats, but not necessarily drought-tolerant. Compare xerophyte.
• xerophyte – A plant generally living in a dry habitat, typically showing xeromorphic or succulent adaptation; a plant able to tolerate long periods of drought. Compare xeromorph.
• xylem – A specialized water-conducting tissue in vascular plants.

Z

• zonate – Having light and dark circular bands or rings, typically on leaves or flowers.
• zygomorphic – Bilaterally symmetrical; symmetrical about one vertical plane only; applies to flowers in which the perianth segments within each whorl vary in size and shape. Contrast actinomorphic and irregular.  
• zygote – A fertilized cell, the product of fusion of two gametes.

Currently Seeking Funding To Continue This Non-Profit, Ad-Free Work

If you are able to donate so that I can continue this non-profit work of supplying people with scientific information on the plant families, native plants, and invasive species found throughout North America, please donate using the GoFundMe link below. Thank you!