Dioneea

Dioneea muscipula (Venus's Fly-trap), the only known species of the genus, a plant belonging to the Droseraceee or Sundew family, native to the swampy ground round Wilmington in Carolina, but now commonly grown in greenhouses on account of its great physiological interest. It has few rootfibres and a scape terminating in a cluster of white flowers, but its important structures are its leaves. These form a radical rosette, not large individually. and pale green in colour. They have winged petioles or adnate stipules and round blades with strong mid-ribs. Round the margin of the leaf are inflexed spinous "tentacles," like the teeth of a gin, and on the upper surface of each half of the leaf are numerous glands and three or four long multicellular hairs. On these hairs being touched by an insect or other nitrogenous body, the normal electric current in the leaf is reversed, as was demonstrated with the galvanometer by Professor Burdon Sanderson, and the two halves of the leaf instantly shut together, the mid-rib acting as hinge. The glands then pour out a copious acid digestive secretion, and the leaf remains tightly closed until the food captured is digested and absorbed.