QUASSIA, in botany, a genus of the monogynia order, belonging to the decandria class of plants. There is but one species, viz. the amara, or bitter-
ash, as it is called in the West Indies. It has of late come into great repute as a medicine, and the root is the part made use of. Its virtues were first revealed by a negro at Surinam, whose name was Quassi. This root appears to be the most pure and intense of all the bitters. At Surinam it has acquired a high character in curing intermitents, even in cases where the Peruvian bark has failed. It may be given in any form; but the most usual is an aqueous infusion, in the proportion of one drachm to a pint, the dose of which is one ounce.