Introduction to the Droseraceae or Sundew Family

Welcome to the Droseraceae family, commonly known as the sundews, after Drosera’s unique sticky hair-like tentacles that glisten in the sun like dew but in reality are a deadly trap to small flies and other insects that get lured in, stuck, and digested and turned into plant food. Yes, the Droseraceae contains the Venus Flytrap, the family’s most famous member.  

This is easily one of my top 5ish or so favorite plant families (because I have many!), in part because I love carnivorous plants. I also love bog plants that find ways to adapt in nutrient-poor, waterlogged environments where most land plants simply cannot even survive. But these little herbs thrive and play a key role in nutrient cycling in bog ecosystems, providing crucial nitrogen, phosphorous, and other minerals that are limited in bogs.

If you’re new to plant morphology, the guide below is a perfect beginner’s description if you want to learn how to identify the Droseraceae or sundew 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 Droseraceae family, information on uses and wildlife values, and pictures of individual Droseraceae species I have photographed in North America. However, for researchers or those wanting to learn even more, further down the page is a Scientific Botanical Description with botanical terms and my genus-level distribution data throughout North, Central, and South America.

Beginner’s Guide to the Sundew (Droseraceae) Family

Leaves and Stems of the Sundew Family

The Sundew family are all carnivorous annual or perennial herbs that typically only inhabit bogs, except Aldrovanda, which is a free-floating carnivorous aquatic. They have small leaves, typically clustered at the bottom in a basal rosette.

The key defining feature is the presence of hair-like “tentacles” in Drosera that are covered in sticky mucilage that traps tiny insects, and the leaves curl up over them and slowly digest them. However, in Aldrovanda and Dionaea the leaves are smoother and flanked by teeth that rapidly snap shut to trap the prey.

Flowers of the Sundew Family

The flowers are mostly bisexual, containing both male (stamens) and female (style, stigma, and ovary) organs in the same flower, and are typically arranged in few flowered clusters on leafless stalks, but sometimes there is only a single flower.

There are usually 5 sepals that are mostly free and remain around the seeds in fruit. There are usually also 5 petals that may be white, pink, red, or rarely yellow or orange and also persist in fruit.

Reproductive Features of the Sundew Family

There are usually 5 fertile stamens, or equal in number to the number of petals, that are free (not fused) and are arranged alternating with the petals.

There are usually 3-5 styles that are often branched or divided, and the ovary is superior (attaches above the point of petal attachment).

Fruits of the Sundew Family

Fruits are mostly small dry capsules enclosed in the persistent calyx and splitting open by 3-5 openings (valves). Seeds are small to dust-like in size.

Morphology of Droseraceae in North America

Some Species of Droseraceae Found in North America

Dionaea muscipula—Venus Flytrap

This familiar plant, the Venus Flytrap, can be found in nurseries and grocery stores all over North America, grown as a short-term novelty plant. It’s a restricted endemic species of the USA found naturally only in North and South Carolina, USA, where it grows in wet, acidic longleaf pine savannas. This one was in cultivation at the Atlanta Botanical Gardens in Georgia, USA.

Drosera anglica—Great Sundew

The Great Sundew is a circumboreal species widely found across North America, Europe, and Asia, easily identified by its upright, strap-like rosette of leaves and completely hairless flower stalk. You can usually find it growing in Sphagnum moss mats and fens. This one was in the Shuswap region of BC, Canada.

Drosera capensis—Cape Sundew

This sundew is native to the Cape region of South Africa; I found it growing in Atlanta Botanical Gardens in Georgia, USA. However, it is also introduced in California, USA, and in Australia. It’s unique for its long, narrow, ribbon-like leaves that often fall over and its long scape with pretty magenta or pink five-petaled flowers.

Drosera rotundifolia—Round-Leaved Sundew

The round-leaved or common sundaw is pretty characteristic of the genus and the Droseraceae as a whole—low-growing herbs with rounded leaves, covered with sticky “tentacles” to capture prey. These are circumboreal and widespread across the northern hemisphere. They are very common in BC, Canada, where this one was photographed.

Uses of the Droseraceae Family

Several of the Drosera species, and Dionaea muscipula (Venus flytrap), are widely used in the ornamental carnivorous plant market, generally micropropagated via tissue culture for retail.

Drosera has been used in herbal medicines in Europe and Asia for centuries, often to relieve dry coughs, bronchitis, and whooping cough. The tuberous forms were a staple diet for many Australian Aboriginal peoples who roasted them and ate the starchy roots.

Ecosystem and Wildlife Values of the Droseraceae

The Droseraceae prey on Diptera, small Formicidae, and micro-Lepidoptera (and aquatic micro-crustaceans and mosquito larvae with Aldrovanda), and by trapping thousands of insects per meter during summer blooms, they help modulate the local insect density.

Their presence in peatlands plays a major role in nutrient cycling, where the animal-derived nitrogen, phosphorous, and trace minerals directly enter the bog peat layer as leaf litter during seasonal senescence.

Despite being carnivorous, their flowers are on tall scapes, keeping pollinators safe from the traps, which is good, especially since they are deceptive in that not many actually produce nectar.

Many members of this family are endangered, with several species already facing local extirpation, and as a result, they are federally protected in many countries. For instance, Aldrovanda is a monospecific genus of Africa, Asia, and Australia that has been extirpated from Austria, the Baltic States, Bulgaria, Greece, Korea, and Uzbekistan, despite also being introduced in the United States.

Taxonomy of the Droseraceae Family

The Droseraceae are a small family made of just 3 genera and about 262 species. They are part of the Caryophyllales order of the core Eudicots. Since they are such a small family, and 2 of the 3 genera are monotypic, we don’t break them into subfamilies or tribes.

Genera of the Droseraceae Family

Aldrovanda (1), Dionaea (1), Drosera (260).

Key Differences From Similar Families

As a carnivorous bog plant with glandular “tentacles,” it is hard to confuse with most other plant families, except other carnivorous plants.

The Drosophyllaceae was historically classified in the Droseraceae, so it is no wonder it is the most commonly confused. Drosophyllum lusitanicum looks like a big, somewhat woody sundew with long, grass-like leaves covered in glistening red stalks. It was historically classified inside Droseraceae. You can tell them apart immediately by habitat: Droseraceae are bog plants that need waterlogged environments, while Drosophyllum only grows in dry, gravelly Mediterranean heath and pine barrens. Also, few of the Droseraceae grow such long leaves, and the few that do are not so stiff; the leaves of Drosophyllum are also incapable of curling around their prey, unlike Droseraceae.

The Lentibulariaceae, or butterwort family, could also be confused simply because they are carnivorous plants with sticky hairs and grow in many of the same environments. However, butterworts have smooth, succulent, or buttery-looking leaves and lack the long dewdrop tentacles. They also produce two-lipped spurred flowers, unlike the 5-petaled regular flowers of Droseraceae.

Scientific Botanical Description of the Droseraceae Family

Habit & Leaf Form of the Droseraceae Family

The Droseraceae are all herbaceous annuals or perennials. Plants are hydrophytic or helophytic to mesophytic and are all carnivorous. They are usually rooted (fibrous, rhizomatous, or geophytic with stem tubers), but Aldrovanda is a free-floating, rootless aquatic.

Leaves are usually small and arranged either in basal rosettes (often) or alternate along the cauline stem, but rarely whorled in Aldrovanda. They are non-sheathing and may be stipulate (fimbriate, scarious, or forming a protective bud/hibernaculum) or exstipulate.

Vernation is predominantly adaxially circinate (coiled inward toward the upper surface), but non-circinate, conduplicate, or inflexed in various lineages. The lamina is simple, typically entire to flabellate, peltate, or spathulate, but deeply dichotomously divided in Drosera binata, or modified into a terminal, bi-lobed bivalve trap hinged along the midrib (Aldrovanda, Dionaea).

Carnivorous Trapping Mechanisms of the Droseraceae

Trapping mechanisms are active, exhibiting two distinct evolutionary syndromes:

1. Adhesive traps (Drosera): Lamina are adaxially covered with multicellular, vascularized glandular emergences (“tentacles”) that secrete an acidic, polysaccharide-rich mucilage with extreme viscoelastic properties. Prey retention induces thigmonastic and thigmotropic incurving of the emergences and, frequently, slow wrapping of the entire lamina mediated by auxin/acid growth and action potentials. Specialized taxa possess dry, bilaterally symmetric snap-tentacles capable of rapid, sub-second mechanical catapulting (Drosera glanduligera, sect. Bryastrum).
2. Snap-traps (Aldrovanda, Dionaea): Lamina are modified into a rapid bivalved closure mechanism flanked by marginal teeth or cilia. Closure is initiated when prey deflects multicellular sensory trichomes (trigger hairs) located on the adaxial surface, propagating electrical action potentials that prompt swift hydraulic leaf bistability and cell turgor changes within 100–200 ms.

Flowers of the Droseraceae Family

Plants are predominantly hermaphroditic, or rarely polygamodioecious or functionally dioecious. Pollination is mostly entomophilous, but the flowers can be autogamous to facultatively cleistogamous (Aldrovanda and high-latitude/alpine Drosera).

Flowers are aggregated in terminal or axillary, scapose, uncoiling scorpioid or helicoid cymes, or rarely are reduced to a single flower (Drosera uniflora, Aldrovanda) or branched into paniculate cymes in certain tuberous Drosera.

Flowers are actinomorphic, typically 5-merous, but sometimes 4-merous or pleiomerous (6-12) in certain Drosera. The perianth is biseriate, dichlamydeous, and isomerous.

The calyx is made of 5(4-8) sepals that are free or basally connate into a short tube. They are regular, imbricate, and persistent in fruit, often glanular-pilose or carinate.

The corolla is made of 5 (2-12) petals alternating with the sepals that are free or rarely basally coherent. They are imbricate or contorted, regular, shortly clawed to cuneate or obovate, membranous, marcescent, and twisting around the developing ovary after anthesis. Petals are typically white, pink, magenta, or red, rarely yellow or orange.

Androecium of the Droseraceae Family

The androecium is composed of 5(4–20) fertile stamens that are free of the perianth and of one another and are usually isomerous and alternating with the petals.

The filaments are filiform to flattened/subulate. Anthers are bithecal, tetrasporangiate, dorsifixed or basifixed, and they dehisc extrorsely via longitudinal slits. Pollen is shed in tetrads (predominantly in Drosera and Dionaea) or monads (Aldrovanda), polyforate or inaperturate.

Gynoecium of the Droseraceae Family

The Droseraceae gynoecium is made of a 3-5 carpeled superior ovary that is syncarpous and unilocular (rarely 3–5-locular with intruded parietal placentae).

There are 3–5 styles, rarely 2, that are free to the base or are basally connate, frequently bifid, flabellate, multi-branched, or fimbriate at the apices (variable and diagnostic in Drosera); often longer than the ovary. Stigmas are capitate, papillose, or branched.

Placentation is parietal or basal. There are 6 (2-5) or to 300+ (in some Drosera) ovules that are ascending, horizontal, or pendulous; anatropous, bitegmic, and crassinucellate (rarely subcrassinucellate).

Fruit of the Droseraceae Family

The fruit is usually dry (rarely slightly fleshy in submerged Aldrovanda) and enclosed within the persistent, marcescent calyx. Dehiscence is predominantly loculicidal via (2–)3–5 valves (Drosera) or may be an irregularly/tardily dehiscent capsule (Dionaea) or indehiscent to irregularly rupturing via rotting of the pericarp under water (Aldrovanda).

Seeds are few to numerous, small to minute and dust-like. They are copiously endospermic, fleshy or oily, and rich in lipids and proteins. Seeds are mostly wingless, but some seeds are flattened and winged.

Global Distribution of the Droseraceae Family

The Droseraceae family, while small, is cosmopolitan and found on all continents except Antarctica, from frigid to tropical climates, absent only in the desert regions. While widespread, they are highly threatened due to habitat destruction. Since they are able to supplement nutrient intake, especially nitrogen, by feeding on insects, it allows them to thrive in low-nutrient places like bogs, which are on the decline around the world.

Distribution of the Droseraceae in the American Continents

Canadian Droseraceae Genera

Drosera 9 spp. cosmopolitan genus are native in all of Canada, including the Arctic (and Greenland).

USA Droseraceae Genera

Aldrovanda 1 sp. introduced to NY, NJ, and VA; Dionaea monospecific former narrow USA endemic native to FL, SC, NC, and NJ, and introduced to WA, CA, GA, VA, and NY; Drosera 14 spp. cosmopolitan genus native to most of the USA, inc. AK and HI, but exc. NV, UT, AZ, SD, NE, and MO.     

Mexico Droseraceae Genera

Drosera 2 spp. cosmopolitan genus native to SW+SE+Gulf Mexico.

Neotropical Droseraceae Genera

Dionaea monospecific former narrow USA endemic is introduced to Jamaica; Drosera ~40 spp. cosmopolitan genus native to CAM (exc. Guatemala and El Salvador), the Greater Antilles (exc. Haiti), Trinidad-Tobago, and most of SAM except N Chile and NW Argentina.

Patagonian South America Droseraceae Genera

Drosera 1 sp. cosmopolitan genus native throughout Patagonia and the Falkland Islands.   

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.
• Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
• 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.
• International Carnivorous Plant Society CP Names Database. (2026). Retrieved September 18, 2026, from https://cpnames.carnivorousplants.org/
• Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. 2009+. Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
• Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
• 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.
• WFO (2022+): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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/