A new species of edible yam (Dioscorea L) from western Madagascar

摘要

A new species of yam from Western Madagascar, Dioscorea slerilis O. Weber & Wilkin, is described and illustrated. It differs from D. Irichanlha Baker mainly in its torus shape (saucer-shaped versus flat and discoid in I), trirha)ilh(i) and the presence of a sterile flower at the base of each cymule of its male inflorescences. It grows mainly in deciduous forests on limestone. Dioscorea Irichanlha is leclotypifivd. The significance of torus shape for the systematics of Dioscorea in Madagascar is discussed.