ÆTHUSA, in botany, a genus of the pentandria digynia class; and, in the natural method, ranking under the 45th order, Umbellate. The characters are: The calyx is an universal umbel expanding, the interior rays shorter by degrees; with a partial umbel, small, and expanding. There is no universal involucre; the partial one is dimidiated, with three or five leaflets,
lets, and pendulous; the proper perianthium scarcely discernible. The universal corolla is uniform, with fertile florets; the partial one has five heart-inflected unequal petals. The stamina consist of five simple filaments, with roundish anther. The pistillum is a germen beneath; with two reflected styli; the stigma obtuse. There is one pericarpium; the fruit is ovate, striated, and tripartite. The seeds are two, roundish and striated. There is but one species, viz. the sethusa synapium, fools-parsley, or lesser hemlock (a native of Britain), which grows in corn-fields and gardens. This plant, from its resemblance to common parsley, hath sometimes been mistaken for it; and when eaten, it occasions sickness. If the curled-leaved parsley only was cultivated in our gardens, no such mistakes would happen in future. Cows, horses, sheep, goats, and swine, eat it. It is noxious to geese.