A look at Drosera

Figure 1. The threatened Water Sundew (Drosera intermedia). Photo taken by:
Noah Elhardt http://en.wikipedia.org/wiki/File:Drosera_intermedia_ne1.jpg
This post is one of a series from Botany professor Nisse Goldberg's students at Jacksonville University. Student author: Keenan Carpenter.

Allow me to introduce you to an odd little group of plants of the genus Drosera, otherwise known as the Sundews. The Sundews belong to larger family group Droseraceae which encompasses the rest of the carnivorous/insectivorous plants. There are five species of Sundew found here in Florida: The Pink Sundew (Drosera capillaris), the threatened Spoon-Leaved or Water Sundew (Drosera intermedia), the Dwarf Sundew (Drosera brevifolia) , the Thread-Leaved Sundew (Drosera filiformis), and Tracy’s Sundew (Drosera tracyi).

Figure 2. A common flower form seen among the members
of Drosera. Photo taken by: Denis Barthel
Sundews are for the most part swamp and bog plants that have managed to work their way into a niche in their environments that not many other plants have been able to inhabit. The members of Drosera make their homes in moist, acidic, and nutrient deficient soil. However, the Sundews have developed a strategy to get the nutrients they need from a different source…

If one was to examine any Sundew they would find that its leaves are covered in numerous tiny hair-like structures (Figure 1) each glistening with a drop of moisture that could easily be mistaken for dew clinging to the plant (Hence one reason for the name!). If they were to investigate further so far as touching one of the glistening hairs they may find the plant springs to life! This interesting adaptation is how the Sundews fill the nutritional gap left by their environment.

Sundews are insectivorous, meaning they feed on insects (Figure 2). That glistening dew-like substance on the leaves is actually a bead of sticky mucus packed with enzymes to digest unwary bugs lured in by the sweet smells the Sundew emits. When an insect lands on the plant the leaves immediately begin to curl around it, covering it in sticky digestive mucus, which will suffocate and eventually digest the insect into nutritious slurry which is then absorbed through the surface of the leaf.

Figure 3. An insect is digested by a Thread-Leaf Sundew.
Photo taken by: Tim Ross
Like many other plants, those in the genus Drosera produce flowers (Figure 3). Sundews flower when they have gathered sufficient nutrients to produce viable flowers and then seeds. The healthier and more well “fed” the Sundew, the more flowers and seeds are produced.

Aside from hybridized and tropical Sundews, the plants typically enter a dormant phase during the colder months of the year (November-February), at which time they form a hibernaculum, a dense cluster of buds made to aid them in toughing out the winter. Other species may die back to a tuberous root called a corm when it is too cold or too dry and then spring forth again when growing conditions are favorable again in the warm and/or wet season. All of the Floridian and North American species form hibernaculum during the unfavorable months.

From early on (Early as the 15th century) the various Sundews have been used for their medicinal properties (Figure 4). It has been seen that Sundews prove effective against a number of gram-negative bacteria (a group of bacteria, among which are those like shigella and salmonella). The leaves also contain quinones which make them effective for combating several bronchial ailments, like bronchitis. The digestive mucus itself is used as a topical treatment for pain and itching and works by distracting the brain with a new sensation.

Figure 4. 15th century book detailing Drosera, perhaps
for the first time.  Photo taken by: Denis Barthel

Sundew Facts

· Sundews seeds can remain viable for fifty years

· In some species a new Sundew can be grown from almost any part of the plant

· Larger Sundews can even take lizards and small rodents as prey items!!!

· Sundews can be fast. Snap trap Sundews can whip their arms in completely in a tenth of a second, literally flinging prey into the sticky center of the plant.

· Sundew leaves grow much like those of ferns, starting curled and gradually uncurling as the leaf matures

· There are approximately 130 species of Sundew scattered across the world

· Modification and cross-breeding has resulted in a strain of D.filiformis that turns completely red in direct sunlight. It’s been named the Florida All-Red.

Sources Cited:

Austin, D. F. 2002. Sundews . The Palmetto, 21(3) 12-13. http://www.fnps.org/palmetto/v21i3p12.pdf (6 July, 2002).
"University of Florida Herbarium Digital Image Search." Florida Museum of Natural History. Web. 10 Nov. 2011. http://www.flmnh.ufl.edu/herbarium/cat/imagesearch.asp?srchproject=CV.

Web. 10 Nov. 2011. http://www.sarracenia.com/faq/faq5240.html .

"The Sundew Flowering and Seed-Collecting Process- When and How Should I Harvest Drosera Seeds?" The Sundew Grow Guides. Web. 10 Nov. 2011 http://www.growsundews.com/sundews/drosera_seed_collecting_sundew_seed_harvesting.html.

"Drosera." Wikipedia, the Free Encyclopedia. Web. 10 Nov. 2011. http://en.wikipedia.org/wiki/Drosera .


Wonderful, thank you! Appreciate the beautiful photos and botanical illustration - hard to beat the art in those old illustrations.
Rich said…
Very cool, thanks for posting. Need to get back to the Botanical Garden soon.

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