Introduction to the Koeberliniaceae Family
Welcome to the Koeberliniaceae, a very tiny plant family with just a single genus and two species, one native to southwestern North America and the other a disjunct endemic of Bolivia. That’s it! However, despite its small size, this family is yet another of my favorites (and I have many!). I haven’t been to Bolivia (yet), so my only experience with this family is the American Southwest. These thorny desert shrubs have huge green thorns that provide an excellent refuge for desert dwellers like birds, lizards, and rabbits, who also love feeding on the berries, which do not taste bad, though they are difficult to pick! I also love how it thrives in inhospitable environments where most plants simply cannot survive. It is a truly admirable plant!
If you’re new to plant morphology, the guide below is a perfect beginner’s description if you are keen to learn how to identify the Allthorn or Koeberliniaceae family, with no need to know any scientific jargon.
Below the guide, you’ll find morphology photos to help you identify the features of the Koeberliniaceae family, information on uses and wildlife values, and pictures of individual Koeberliniaceae species I have photographed in North America, organized by supertribe and tribe, so you can start to see the relationships within the family as well.
Beginner’s Guide to the Allthorn (Koeberliniaceae) Family
For researchers or those wanting to learn more, further down the page is a Scientific Botanical Description and my genus-level distribution data throughout North, Central, and South America.
Leaves and Stems of the Allthorn Family
The allthorn family are shrubs or small trees with green, photosynthetic stems, no true leaves (reduced to scales), and are densely armed with long, sharp thorns at the ends of short branches that interlock to create an impenetrable thicket.
Flowers of the Allthorn Family
Allthorn members produce clusters of flowers, sometimes solitary, in the axils of the branchlets (where the branchlet meets the branch). Flowers are bisexual with both male (stamens) and female (ovary, stigma, style) parts in the same flower.
Flowers have 4 free petals that are creamy-, greenish-, or yellowish-white and 4 greenish sepals that are free or slightly joined at the base.
Reproductive Features of the Allthorn Family
Allthorns have 8 free stamens and an ovary that attaches above the point of petal attachment (superior) with a single thick style and simple stigma on top.
Fruits of the Allthorn Family
Fruits of the allthorns are fleshy, edible berries that are shiny black or dark purple when mature, with persistent sepals at their base and parts of the persistent style forming a pointy-looking tip (but not sharp or thorny).
Morphology of Koeberliniaceae in North America
There is Only One Species of Koeberliniaceae Found in North America
Koeberlinia spinosa—Crown of Thorns, Allthorn
Koeberlinia spinosa is one of only two members of the tiny Koeberliniaceae family, shown here with its characteristic interlocking thorny branches that make it an impenetrable thicket. The stems and thorns are photosynthetic, and it produces no visible leaves, as they are reduced to drought-deciduous scales. This plant has lots of little green fruits visible that are still maturing. It was found near Alamogordo, New Mexico, United States.
Uses of the Koeberliniaceae Family
While there are no commercial uses, Koeberlinia spinosa berries are edible and were part of indigenous diets in the American Southwest and Mexico, and smoke from the wood was used for medicinal and ceremonial purposes.
In modern desert landscaping they make excellent border plants for xeriscapes because the interlocking thorns are an impenetrable living security barrier or natural fence. However, they grow very slowly so they generally are not available commercially.
Ecosystem and Wildlife Values of the Koeberliniaceae
Due to their spiny nature, the shrubs make a valuable wildlife refuge for small birds like quail and cactus wrens, reptiles, desert rabbits, and more, keeping them safe from larger predators. They also create a nurse canopy to shelter desert seedlings from extreme temperatures.
The flowers produce abundant nectar that feeds native bees, wasps, flies, and moths, while the fleshy berries are eaten by numerous birds, rodents, and other desert dwellers. And while it is inedible to herbivores most of the year, they will feed on the fleshy new shoots after seasonal rains.
Taxonomy of the Koeberliniaceae Family
The Koeberliniaceae was designated as a family back in 1895; however, authors mostly still included it in the Capparaceae family until recent molecular studies supported its removal and designation as its own family.
Still, it sits solidly in the Brassicales order since it produces mustard oils (glucosinolates) just like Brassicaceae and most members of the order, and it also has 4 sepals, 4 petals, and a superior ovary, which are characteristic of the order.
Genera of the Koeberliniaceae Family:
Koeberlinia (2).
Key Differences From Similar Families
Since they are closely related and were once included in the Capparaceae family, these are the most common ones to mistake for Koeberlinia, as they share a woody habit, flowers with 4 petals, and both produce berries. The Capparaceae can be distinguished by usually having more than 8 stamens, often up to 100 or more, and often having a very long gynophore; they also occasionally produce dehiscent capsules or woody-shelled fruits (amphisarcas) instead of berries.
Scientific Botanical Description of the Koeberliniaceae Family
Habit & Leaf Form of the Koeberliniaceae Family
The Koeberliniaceae are shrubs or small trees, up to 5 m tall, with heavily branched stems that form a dense, impenetrable, rounded or flat-topped thicket. It has alternate, spirally arranged leaves, which are sessile, very minute, scalelike, and drought-deciduous, so the leaves are seldom noticeable. Despite being technically deciduous, it is functionally evergreen via photosynthetic stems.
Branches are densely armed with lateral branchlets that diverge nearly at right angles and interlock with each other, creating a formidable barrier. The branchlets are short, rigid, and terminate in characteristic sharp green thorns 1.5-5 cm long, which make the family easy to identify.
Flowers of the Koeberliniaceae Family
Koeberliniaceae inflorescences are racemose, corymbose, or solitary, located in branchlet axils on short peduncles. Bud scales are usually persistent at the base, and bracts are usually absent. Pedicels are present and slender. An intrastaminal nectary disc or glandular tissue is present around the base of the ovary.
Flowers are bisexual, small, actinomorphic, rotate to crateriform, campanulate, or urceolate; the perianth and androecium are hypogynous.
There are 4 sepals that persist in fruit and are free or slightly connate at the base, all greenish and equal.
There are 4 distinct petals in the corolla, inserted on the receptacle, and they are imbricate, distinct, equal, and greenish-white to cream or pale yellow in color.
Androecium of the Koeberliniaceae Family
The Koeberliniaceae have 8 free stamens with slender filaments that may be hairless or slightly puberulent, taper upward, and are slightly expanded at the base. Anthers dehisce via longitudinal slits.
Gynoecium of the Koeberliniaceae Family
The Koeberliniaceae gynoecium consists of a sessile ovary that is 2-locular (2 fused carpels), with axile placentation and 1-4 ovules per locule that are anatropous and bitegmic.
There is 1 short, thick style and a capitate terminal stigma without any lobes.
Fruit of the Koeberliniaceae Family
The Koeberliniaceae always produce indehiscent, spheroidal, fleshy berries 3-6 mm in diameter that mature to a shiny black or dark purple and are subtended by a persistant calyx and tipped with a persistent remnant of the short style. Seeds are small, blackish, shiny, and smooth to slightly rugose with scant or absent endosperm, with 1-4 (usually 2-4) per fruit.
Distribution of the Koeberliniaceae Family
The Koeberliniaceae is a small family with just two species. One is found in southwestern North America (United States and Mexico), while the other is in Bolivia in South America. They are found nowhere else in the world.
Distribution of the Koeberliniaceae in the Americas
Canadian Koeberliniaceae Genera:
Absent
USA Koeberliniaceae Genera:
Koeberlinia spinosa is a North American endemic species native to CA, AZ, NM, and TX.
Mexico Koeberliniaceae Genera:
Koeberlinia spinosa is a North American endemic species native to north and central Mexico, mostly in Chi, Coa, NL, Tam, Dgo, Zac, SLP, Hdg, Son, and BCS.
Neotropical Koeberliniaceae Genera:
Koeberlinia holacantha is endemic to Bolivia in the dry inter-Andean valleys.
Patagonia Koeberliniaceae Genera:
Absent
Additional Information and References
- Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
- Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, along with my own personal observations throughout North America.
- FNA 1993+. Flora of North America. https://floranorthamerica.org/Main_Page. Accessed 2022-current.
- iNaturalist.org 2020+. https://www.inaturalist.org/. Accessed 2020-current. If you like plants or nature in general, please join the iNaturalist community and start sharing your observations with others. The data we track is invaluable for scientists like me wanting to track population changes over time.
- POWO 2019+. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/. Accessed 2020-current.
- Stevens, P. F. 2001+. Angiosperm Phylogeny Website. Version 14, July 2017 [more or less continuously updated since]. http://www.mobot.org/MOBOT/research/APweb/
- USDA, NRCS. 2020+. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; Accessed 2020-present.
- Watson, L., and Dallwitz, M.J. (1992). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
- WFO (2022+): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current
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I am currently seeking funding to expand my website and SEO capabilities as I keep adding new families, and I am also looking to invest in a new macro lens, as I will soon be adding floral dissections to some of the families. Donate to support native plant education using the GoFundMe link, also at the bottom of the page.
Copyright Information
The information and the photos on this site are free to use for educational purposes, with proper attribution. For other uses, please contact me first.
You can cite this site as Willis, Lyrae (2020+). Lyrae’s Nature Blog – Plant Families of North America. https://lyraenatureblog.com/
