Abstract: 1.The external morphology of a Chinese drug,Yang-Chin-Hua(Flos Daturae) is studied in order to identify the plant that yields it. 2.According to the morphology of the flower,Yang-Chin-Hua is determined as containing two kinds of flower.One belongs to Datura metel L.,and the other D.innoxia Mill.The former is known in the Chinese drug store as southern Yang-Chin-Hua,while the latter as nothern Yang-Chin-Hua. 3.Datura metel L.is distinguished from other species of Datura known in China by:(1)its white funnel-shaped flowers with five very shallowly cut lobes and a notch between each two of them;(2)somewhat pendulous fruit with stout spines. 4.Datura innoxia Mill.is characterized by:(1)its densely tomentose stem and foliage;(2)its large white flowers with five triangular petals alternatie with five triangular appendages in between;(3)its somewhat pendulous fruit with long,slender and rather soft spines.