GYMNOSPERMS.) Various poisonous plants of the parsley family (Umbelli f erae) are also called hemlock, as the poison hemlock and the water hemlock (qq.v.). The fool's-parsley (Aethusa Cynapium) is known as lesser or small hemlock. Because of the resemblance of its foliage to that of the eastern hemlock the American yew (Taxes canadensis) is frequently called ground hemlock. (See