%monopetalou%

a. [ Mono- + petal: cf. F. monopétale. ] (Bot.) Having only one petal, or the corolla in one piece, or composed of petals cohering so as to form a tube or bowl; gamopetalous. [ 1913 Webster ]

☞ The most recent authors restrict this form to flowers having a solitary petal, as in species of Amorpha, and use gamopetalous for a corolla of several petals combined into one piece. See Illust. of Gamopetalous. [ 1913 Webster ]