Butterwort; a genus of the monogynia order, belonging to the diandra clafs of plants. There are four species; of which the most remarkable is the vulgaris, or common butterwort, growing commonly on bogs or low moist grounds, in England and Scotland. Its leaves are covered with felt, upright pellucid prickles, secreting a glutinous liquor. The flowers are pale red, purple, or deep violet colour, and hairy within. If the fresh-gathered leaves of this plant are put into the strainer through which warm milk from the cow is poured, and the milk let by for a day or two to become acidulent, it acquires a consistency and tenacity, and neither whey nor cream separate from it. In this state it is an extremely grateful food, and as such is used by the inhabitants of the north of Sweden. There is no further occasion to have recourse to the leaves; for half a spoonful of this prepared milk, mixed with fresh warm milk, will convert it to its own nature, and this again will change another quantity of fresh milk, and so on without end. The juice of the leaves kills lice; and the common people use it to cure the cracks or chops in cows' udders. The plant is generally supposed injurious to sheep, by occasioning in them that disease called the rot. But from experiments made on purpose, and conducted with accuracy, it appears, that neither sheep, cows, goats, horses, or swine, will feed upon this plant.