D. bulbifera is the most widespread species of the genus, extending through tropical Africa and Asia to the remotest Pacific islands. It has been in cultivation in Asia and Africa for thousands of years and many ennobled races (cultivars) exist in Asia (see Prain & Burkill in Ann. Roy. Bot. Gard. Calc. 14: 111–132 (1936)). The best-known Asiatic race is known as var. sativa, whilst in Africa a different edible race with angular aerial tubers has been evolved, known as var. anthropophagorum. This has been introduced to tropical America.Unfortunately in the absence of knowledge of the aerial tubers, and of the presence or absence of terrestrial tubers, it is not possible to distinguish the cultivated variety from the typical wild variety (var. bulbifera) and many gatherings in herbaria cannot be satisfactorily determined. As a result the distributions given above are very incomplete. An added complication is that, in the sterile state, it is not possible to distinguish var. bulbifera from the closely allied D. asteriscus Burkill, which is apparently more frequent than D. bulbifera in eastern Africa.