Fauna beware

Day of the Triffids by John Wyndam was one of the first books I ever borrowed from a library, and it probably had a lot to do with my following science as a career. The story describes a world where humankind, blinded after watching a spectacular meteorite shower, is at the mercy of carnivorous plants (called Triffids) which roam the country-side killing all and sundry. Even to this day, whenever I observe a shooting star I do it with one eye closed … just in case.

Some triffid-like carnivorous plants showing signs of life at the moment are plants of the genus Droseraceae (from the Greek word drosos meaning dewdrops), the Sundew plants. Though not as sexy as the well-known Flytraps, which catch their prey by snapping shut their leaves, the way in which sundews capture their food is equally interesting.

Sugar Ant trapped in Scented Sundew leaves

Each leaf of the sundew sprouts a number of tentacles that exude sweet liquid, which attracts insects (see photo above). When the insects touch this sticky liquid they become trapped and eventually die either of exhaustion in trying to escape, or asphyxiation as the sticky goo covers them. Enzymes are then released to dissolve the insects and the plant absorbs the nutrients. The picture (right) shows a mosquito trapped in the sticky tentacles. The black debris seen on the leaves are the remains of digested insects.

Scented Sundew

The commonest species of sundews in our area are the Scented Sundew (Drosera aberrans) and the Tall Sundew (Drosera peltata). In Scented Sundews, which are flowering now (pictured left), the leaves lie along the ground. In Tall Sundews these leaves are on stems (pictured below), making them look much more sinister and triffid-like. It has pale pink flowers in early summer.

Tall Sundew

These sundews won’t dissolve your leg, should you stand on one, unless you’re a mosquito. The Tall Sundews stand about 50 mm high so kangaroos and possums are safe from entrapment. But knowing evolution, it’s just a matter of time.