top of page
Drosera capensis 'Alba'

Drosera capensis 'Alba'

SKU: 00328

This page is under construction - check back for more information over the weekend!

  • Droseras - What, Where, How, Why?

    As of Sept 30, 2022, This thorough exploration of Sundews (Droseras) is currently being worked on so please excuse any obvious typos or omissions. Please check back later if it is not yet complete. Thank you for your interest in these awesome plants as well as our content. We strive to provide the most comprehensive information about our plants as possible and will be finishing this as soon as possible!

    Droseras are a genus of carnivorous plants with almost 200 species widely distributed around the world in both tropical and temperate regions. Their leaves and other organs are covered with specialized trichomes (plant hairs) with mucilaginous glands on stalks producing sticky resin and digestive enzymes which lure, trap and consume insects. Upon contact with an insect, these trichomes, (referred to as "tentacles" in the context of Droseras), signal the leaf to wrap itself around the prey, forming a pocket that traps it. The insect is then enzymatically digested and the remains, particularly the organic nitrogen from the proteins, are absorbed by the plant. This particular and fascinating evolutionary innovation allows Droseras and other carnivorous plants to grow in very nitrogen-poor conditions. 

    Commonly referred to as "Sundews", Droseras are so named (colloquially and in Latin) for the substances they produce at the end of their trichomes that appear like the morning dew but appear in the middle of the day even in bright sun.

    Their evolutionary adaptation in order to live in their otherwise infertile natural habitats has been a fascinating subject for evolutionary biologists going back to Charles Darwin himself who allegedly was quite taken by Drosera rotundifolia. More recent molecular analyses of some Droseras suggest that this group has become so adapted to carnivory that certain species (eg. Pygmy Droseras) lack an enzyme - nitrate reductase - common to almost all plants on earth that allows them to utilize nitrate in the soil. Thus Pygmy Droseras can be considered "obligate carnivores" as they can ONLY use reduced organic nitrogen from digesting other organisms (or possibly from ammonia). 

    In practical terms, unlike many other carnivorous organisms that do not require "feeding" if grown with some available nitrogen, many Droseras require or at the very least, benefit enormously from being given the occasional "meal". Without it, some species will simply die, some will shrink, and some will cease to grow. Even more generalized, hardier species benefit enormously from "feedings" which can induce growth spurts and increase flowering. Luckily Droseras are easy to feed for the most part and only need to be fed occasionally, once a month is plenty. Plus actually feeding your houseplant a piece of food is a novel and fun experience that delights children and adults alike and no doubt contributes enormously to the popularity of these unique plants. 

    Taken together, Droseras are an extremely diverse and ancient lineage of angiosperms that have survived and been evolving for millions of years. It is unsurprising that their epicenter of diversity is the far-flung continent of Australia with 50% of all known species and the most diversity among species.

    Because of their evolutionary age compared to other carnivorous plants, Droseras have a huge amount of diversity and the widest global range - by far - from the equatorial tropics to temperate and even cold regions well into Canada and even Alaska. They range as far south as New Zealand and the southern tip of South America. Found on all continents except Antarctica, Droseras’ range includes almost the entire continental United States except the dryest regions in the Southwest and range north, just shy of the territories in Canada, continuing northward along the southern Alaskan coast into the Aleutian islands. Many species are found in boggy areas and wetlands. Globally, they tend to be absent from desert regions and species from dryer climates have diverse and elaborate adaptations to deal with the, often seasonal lack of moisture - their diversity is the highest in arid Australia both in the number of species and the diversity of those species. South America and Africa also host many species and even the temperate regions of North America and Eurasia have a few native varieties. Due to the extremely high biodiversity of Sundews in Australia, along with their presence on every continent, they are most likely to have first evolved there before the breakup of Gondwana.

    Despite their cosmopolitan presence, some botanists such as Luwig Deils notes that they are conspicuously missing from several regions where they would be expected including notably many rainforests as well as the American Pacific Coast though that’s been contradicted.    

    Droseras share a common body plan around a rosette crown but are otherwise highly diverse in form from "rosetted" types where the petioles and leaves are prostrate or lie flat against the substrate, to upright types that can be more than a meter tall. There are climbing species and tuberous species whose biomass is primarily underground. All Droseras possess and are covered with modified trichomes called glandular hairs or "tentacles" that help attract and trap prey. All are able to move their tentacles (thigmonasty) - usually inward so that more tentacles make contact with the trapped prey. The "dew" at the tips of the tentacles is made of sweet mucilage (to attract prey) along with a concoction of digestive enzymes that together, turn an insect into a nutrient soup that is absorbed by the surface of the leaf - often by specialized sessile glands. Many species are also able to slowly move and reshape their leaves around the prey, not unlike a Venus FlyTrap with Drosera capensis being the fastest to do so in 30 minutes. This allows the plant to better digest and absorb its bounty.

    The tentacles serve as bait, trigger, trap, and digester. Darwin, a big fan of Sundews, is said to have discovered that the detection of prey by a single tentacle is enough to initiate the Sundew's response. The movement of the tentacles uses a typical auxin-mediated cellular expansion mechanism similar to various tropisms among plants in general. Interestingly enough, however, the detection of motion by the tentacles results in the firing of an 'action potential' - the same type of rapid electrical biological signaling used by our brain and nervous system. The detection of the lightning-fast action potential sets off the much slower orchestra of mechanical and physiological responses to trap and digest the prey.

    Among the non-Australian Sundews, there are two primary types. The subtropical sundews that inhabit frost-free regions and the temperate sundews that have to deal with winter. Subtropical sundews are like most subtropical plants and maintain a somewhat consistent vegetative growth state year-round while temperate sundews are usually ‘hemicryptophytes’ - capable of forming protective structures called a hibernaculum (similar to the pupae of insects) in which they lie and wait until the spring and resume their carnivory with their vegetative parts unharmed. For some species, this is required and must be allowed to hibernate annually while other temperate species are able to maintain their vegetative state year-round as long as the conditions allow. This natural ability makes it possible to keep your sundews outdoors even in northern winters though most Sundew enthusiasts will bring their plants (especially those that do not require hibernation) indoors during autumn.

    Since Sundews are angiosperms, they reproduce sexually through by flowering, pollination, and seed formation. For such interesting and physiologically divergent plants, Sundews produce relatively common flowers, virtually always radially symmetrical with five petals and both male (stamen, pollen) and female (pistil, ovary) parts. Flowers are simple (non-compound). They are almost always produced on tall stalks, keeping potential pollinators far from the deadly traps below, and tend to be open for only a short amount of time. Flower production is often bolstered when the plant has been well fed and induced by high light intensity such as long periods of direct sunlight. The flowers are also heliotropic and follow the movement of the sun. Many species can self-pollinate if the flowers have not been successfully pollinated. Once pollinated, the ovary forms a seed capsule containing many small seeds that are either able to germinate in the right conditions or require a period of winter dormancy termed stratification. Generally, subtropical species produce seeds that can germinate immediately while temperate species’ seeds require stratification to ensure they germinate after the winter.

    Vegetative reproduction is also widespread among Sundews and are a natural part of life for many species. Some of the more derived varieties in Australia have evolved ways of doing so intentionally but most Droseras can produce new plantlets from root tissue that is gets too close to the surface or older leaves that are touching the ground - not unlike some ferns.           

    Because Sundews acquire the bulk of their mineral nutrition through their carnivory, they, like many carnivorous plants, have fairly simple root systems primarily for the absorption of water and to anchor them in place. Though their roots are inadequate for the uptake of mineral nutrients, Some species have evolved more novel uses for their roots - such as for vegetative reproduction. Among the diverse Australian species some use their roots for the storage of water and other resources. Interestingly, some temperate species, namely D. intermedia and D. rotundifolia appear capable of forming arbuscular mycorrhizae, a complex type of interaction with beneficial fungi (mycorrhizae) that allows them to penetrate into the organ itself, thus increasing its ability to uptake water and even mineral nutrients. This may allow these species to use their otherwise meager roots to utilize nutrients in the soil, if available, to supplement or even replace the nutrients otherwise obtained through carnivory in the event that prey is lacking. 




$29.98 Regular Price
$19.98Sale Price
Out of Stock

Related Products