TETRADYNAMIA, (τετραδύναμια "four," and δύναμις "power"), four powers; the name of the 15th class in Linnæus's Sexual System, consisting of plants with hermaphrodite flowers, having six stamens, four of which are long, and two short; it corresponds to the filiqueuse of Ray, and cruciformes of Tournefort. See BOTANY, p. 1296.