contrayerva; a genus of the monogynia order, belonging to the tetrandria clas of plants. There are four species, all of them low herbaceous plants, growing in the warm countries of America. The root is used in medicine. It is full of knots; an inch or two in length, about half an inch thick; DOR, [2518] DOU

Dorsum thick; externally of a reddish brown colour, and pale within: long, tough, slender fibres shoot out from all sides of it, which are generally loaded with small round knots. The root has a peculiar kind of aromatic smell, and a somewhat astringent, warm, bitterish taste, with a light and sweetish kind of acrimony when chewed. The fibres have little taste or smell; the tuberous part therefore should only be chosen.—Contraryva is one of the mildest of those substances called alexipharmacies: it is indisputably a good and useful diaphoretic. Its virtues are extracted both by water and rectified spirit, and do not arise by evaporation with either.—The plants cannot be propagated in this country without the greatest difficulty.