The bulbils of Dioscorea sansibarensis fall at maturity and are carried away from the parent plant, if at all, by water: they rest through the Dry season; and germinate when the soil under them is able to supply moisture. The new plant, is thrust into the surface of the soil and there shaped by its geotropic responsiveness. Its tuber is the result of a more or less one-sided enlargement of the first internode of the axis: it is perennial and its greatest growth becomes annular. The annual stems, which rise from the tuber are produced cymosely, each from the lowest axil of its parent axis; and, by arrest of internodes between them, all are sessile on the tuber. Thus crowded they are unable to grow in positions which are theirs theoretically and are accommodated by a certain amount of fluidity in the growth of the top of the tuber. D. sansibarensis must be excluded from the section Opsophyton because its tubers are more specialized organs than its bulbils, as well as on differences in the male inflorescences.