14 Nov Carnivorous plants that glisten in the sun
By Dr Kirsti Abbott, UNE Discovery Voyager
You may have noticed at your feet, as you trudged through sandy moist ground, small flower like plants glistening in the sunlight, with what look like dew drops on their tiny rounded leaves. They are carnivorous plants in the genus Drosera; a large and diverse group of beautiful plants that typically live in nutrient poor soils and therefore need to supplement their deficiencies with the nitrogen-rich bodies of insects.
Sundews, as they are referred to, occur on all continents on earth except Antarctica. Their rosettes can be as small as 0.5cm high up to a metre! And some climbing species can reach lengths of up to three metres. They can live between two and 50 years, and in harsh conditions like dry, hot summers or cold winters, can go into hibernation, reduce their leaf area and wait until the environment is more to their liking to show their shimmering beauty.
The leaves of sundews have many small tentacles that finish in a droplet of mucilage, a sticky substance that looks like water but acts like a glue for insects that accidentally land on them. The tentacles respond to the insect’s movement by enveloping their prey, channeling the dead body toward the centre of the plant for digestion. The tentacles are so sensitive that, according to Charles Darwin, the contact of the legs of a small gnat on a single tentacle is enough to induce a response.
Charles Darwin was inordinately fond of these little plants, so much so that his wife noted his fascination with them as he conducted his early experiments on Drosera. Darwin made thousands of drawings that appeared in his book ‘Insectivorous Plants’ (~1876) that also documented the biology, ecology and physiology of pitcher plants, fly traps and other carnivorous plants. He was curious about the mechanisms that these plants evolved to move, and trap and digest insects.
At one time, Darwin declared: “I care more about Drosera than the origin of all the species in the world.”
In the New England, there are many species of Drosera to be found. Look in areas of sandy soil, good sunlight and usually wet underfoot for a good part of the year. In Armidale you can see sundews around Dumaresq Dam and surrounding areas.
So next time you’re on a bushwalk, look down at the little things at your feet. You might just catch the sundews glistening in the sun, waiting to kill and digest an unsuspecting insect for lunch!