A genus of worldwide distribution comprising over 300 species, the sundews display a wide variety of physical characteristics and environmental adaptations. However, all species share the common characteristic of leaves armed with many tentacles-each topped with a droplet of sticky mucilagenous glue. This glue glistens on the leaves in sunlight-giving the plants their common name.
Flying and crawling insects are attracted to the leaf by the sugary glue and upon alighting are immediately held. As the animal struggles to free itself, it's movements trigger surrounding hairs which gradually bend over and hold the prey in place. In some cases the whole leaf has the power of movement, completely encasing it's prey and making escape impossible.
As the insect moves it becomes covered in the glue and suffocates as it's breathing pores become blocked. Digestive enzymes are then released through the tentacles to break down the soft parts of the insect.
The resulting nutrients are then absorbed back through the tentacles and in to the leaf.
Species found in temperate regions (including the British Isles) adapt to their environment by producing tight dormant buds called hibernacula over the winter months. These protect the plant from freezing temperatures and once the warmer days return, growth resumes.
Many species need to survive high temperatures over the summer months, and employ other tactics.
These plants usually live in seasonally wet areas, which dry out completely during this time.
The majority of these are from Australia and South Africa, and lose their growth when the temperatures increase. Some Australian species are tuberous and retreat under ground to a small tuber (which is the same structure as a potato). They remain in this state for the summer and resume growth when the temperature drops and the rains return in the autumn.
One group also from Australia are known as the Pygmy Sundews, and include the smallest of the Drosera species. These are all small plants and those that live in seasonally wet areas produce a tight silvery stipule bud which encloses the growth point of the plant, protecting the plant from the burning heat of the sun.
They also have extremely long hair-like roots which penetrate deep in to the soil to reach any available moisture.
Some South African plants produce thick fleshy roots to help them survive the summer, and prout from these for the winter growth period, dying back again when the summer heat returns.