BUTTERWORT, the popular name of a small insectivorous plant, Pinguicula vulgaris, which grows in wet, boggy land. It is a herb with a rosette of fleshy, oblong leaves, I to Sin. long, ap pressed to the ground, of a pale colour, and with a sticky surface. Small insects settle on the leaves and are caught in the viscid se cretion. This, like the secretion of the sundew and other insec tivorous plants, contains a digestive enzyme which renders the nitrogenous substances of the body of the insect soluble and ca pable of absorption by the leaf. In this way the plant obtains ni trogenous food by means of its leaves. The leaves bear two sets of glands, the larger borne on usually unicellular stalks, the smaller almost sessile. When a fly is captured, the viscid secretion comes strongly acid and the naturally incurved margins of the leaf curve still further inwards, rendering contact between the insect and the leaf-surface more complete. The plant is widely tributed in the north temperate zone, extending into the arctic zone. In North America it ranges from the high northern tundras southward to Newfoundland, New York, Minnesota, tana and British Columbia. The butterwort belongs to the derwort family ceae) which comprises various other carnivorous plants. (See