TRAP TYPE: Flypaper Trap
Currently Ca. 152 listed species occupying temperate and tropical habitats
throughout the world.
The master of sticky fly paper, Drosera (sundew), is a slow trap compared
to the one in Venus Flytrap. However, the sundew relies on first trapping
its prey with its sticky, glandular hairs, as shown in Figure 1, before
it slowly rolls up the edges of the leaf. It does not fold
like the Venus fly trap, but it can effective enclose small flies with
the numerous hairs.
The sundews, so named because their glandular leaf hairs glisten like
dew in the sun, are not only common in bogs, but can occur on sandy banks
and other mineral soils poor in organic nitrogen and phosphorus. So fascinating
is this tiny plant that Darwin (1875) spent 285 pages of his book on insectivorous
plants describing his own experiments on it.
The hairs are stalked glands (Figure 3, 4 & 5) and produce digestive
juices that decompose the trapped prey. These digestive enzymes, including
protease and phosphatase, increase in production once a prey has been
captured, reaching maximum concentration about the fourth day.
Although one sundew is hardly an effective means of eliminating insect
pests, Oliver (in Heslop-Harrison, 1978) counted insects trapped in a
sampling of plants in England and estimated that about six million insects
were trapped in a bog of about two acres!
Darwin cultivated sundews and showed that those that were fed insects
were more vigorous, produced more flowers, and set more seeds than the
ones that were denied any prey (in Heslop-Harrison, 1978). Pate and Dixon
found that 40% of the amino acid arginine stored in the underground corms
of Drosera had come from the insects they had experimentally fed with
labeled nitrogen (in Heslop-Harrison, 1978).