Wednesday, May 17, 2017

The Coolest Plant Ever: Cape Sundew

Drosera capensis, commonly known as Cape Sundew is a carnivorous plant native to the Cape in South Africa. The Cape Sundew is the best of nearly 194 species of Sundews, categorized by the hairlike, mucilaginous glands covering their leaf surfaces. Cape Sundews are made of scapes (a long stem) surrounded by many long leaves or "tentacles," that are covered in the hairlike glands.


Unlike other, boring, carnivorous plants, they do not catch their prey using pitfall traps (e.g. pitcher plants), or by folding (e.g. Venus flytraps), but by using their sticky hairs to lure and trap small arthropods (like flies and spiders). 

Figure 1: The sticky hairs of a Cape Sundew (D. capensis)

Figure 2: A cultivated Cape Sundew (D. capensis) plant.

Plant Food: Trapping Prey
The Cape Sundew, like all other Sundews, is covered in brightly colored, sticky hairs. Unlike all other Sundews, it has tentacle leaves that curl up into fun spirals. When an insect lands on one of its tentacles, it slowly rolls its it up to trap the insect on more sticky hairs and prevent escape.


Figure 3: A Cape Sundew (D. capensis) spiral



The time it takes for a Cape Sundew to trap its prey is longer than other digestive plants, but the digestion only takes around six hours (which is very fast compared to the 5-12 day digestion period of a Venus fly trap). Between attracting, trapping, and digesting its prey, the Cape Sundew does a ton of work.

Thigmotropism:

Thigmotropism is a plant's directional response to its sense of touch. When an insect lands on a Cape Sundew, a process called "differential growth" is started. During this process, cells on the non-contact side of the tentacles are stimulated to grow, and cells on the contact side are compressed. This is what allows the Cape's leaves to curl around and trap insects to be digested. Cape Sundews have an extremely sensitive sense of touch so they can tell when an insect lands on them.


Figure 4: Thigmotropism


Figure 5: Cape Sundew (D. capensis) reacts to insect

Special Enzymes:
Since arthropods have exoskeletons, Cape Sundews need the help of some extra enzymes to digest them. There are two different types of glands on their hairs: stalked glands that attract insects and secrete enzymes to digest them, and sessile glands that absorb the remaining bug juice (ew). Once an insect is trapped, the plant will secrete esterase, peroxidase, phosphatase and protease enzymes to help dissolve and digest it.



Flowers and Roots

Cape Sundews produce small, pink flowers in a row at the end of their scapes. Their flowers can self pollinate and are controlled to be open for just one day so that only one flower is open at a time (isn't that crazy?).

Figure 5: A flowering Cape Sundew (D. capensis)

All Sundew species are found in nutrient-poor, acidic, moist soil. Like other carnivorous plants, the Cape Sundew digests insects in order to supplement their diet. Digesting insects supplements their diet, providing them with key nutrients like nitrogen (more about that here). Because it gets most of its nutrients from digesting insects, its roots are generally useless for nutrient uptake, and mainly serve to anchor the plant and uptake water.

Figure 7: A wild Cape Sundew (D. capensis)

Taking Care of Your Own Cape Sundew

Clearly, Cape Sundews are superior to all other types of plants, and should be the go-to for starting a garden. They are extremely easy to grow, and will eat all (okay, maybe not all, but some) of the insects roaming around your house/garden. Just in case you decide you want one, here are some care tips:

Lighting: bright, indirect light
Water: keep soil evenly moist (they do prefer moist to dry but don't drench them)
Humidity: they are native to tropical environments, and prefer medium-high humidity
Temperature: average room temperature is best, but they prefer warm over cold
Fertilizer: DO NOT FERTILIZE- fertilizer is for plants that take in nutrients the normal way (through the roots), and can harm your plant. You will, however, need to feed it flies to keep it alive. 

Good Luck!




No comments:

Post a Comment