Little shop of horrors for protozoa.

For the first time, botanists have found a carnivorous plant that preys on protozoa.

The discovery ends considerable puzzlement over lifestyles in the genus Genlisea. Discovered at the beginning of the last century, these rare plants form tiny rosettes of leaves on the ground and send up flowers that look like snapdragons. Darwin guessed that the wad of pale, rootlike strands trailing underground from the rosette might trap some kind of creature. "But it's underground--what could it catch?" asks Wilhelm Barthlott of the University of Bonn in Germany.

The plants can survive in soils so poor in nutrients they're practically glass, like Brazilian quartz sands. Yet even in these extremes, a Genlisea typically sports showy flowers, a bit like the tax cheat living too well for his or her ml known resources. "It has to have an additional source of income," jokes Barthlott.

These dainty beauties are actually specialized death traps for protozoa, Barthlott and his colleagues report in the April 2 Nature. Y-shaped forks at the tips of the underground strands secrete chemicals that attract protozoa, say the researchers. They found that paramecia streamed to cubes of agar which had picked up the attractants from contact with the strand ends. This is the first example of a carnivorous plant secreting a chemical lure, says Barthlott.