Some remarks on the taxonomy of the Plumerioideae (Apocynaceae)

Abstract

The family of the Apocynaceae is usually subdivided into two subfamilies, the Plumerioideae with the type genus Plumeria from tropical America, and the Apocynoideae, often named Echitoideae, with the type genus Apocynum from North America. These subfamilies show two characters which are more or less diagnostic for all members.

However, since the taxonomists have built up the present scheme of the Apocynaceae, phytochemists have observed that many plants belonging to the Plumerioideae contain alkaloids, and that many representatives of the Apocynoideae contain glycosides. Some of the alkaloids, e.g. those of Catharanthus, Rauvolfia and Voacanga, and some of the glycosides, e.g. those of Funtumia and Strophanthus are of medicinal interest.

In the present paper, the arrangement of the genera within the Plumerioideae is mainly that of Pichon (1949, 1950, 1953a, 1953b). He subdivided all tribes, except the Tabernaemontaneae, into subtribes, which is an excellent concept according to the present author. The latter, however, does not always agree with the delimitation of the genera. For instance, he does not accept the sinking of Acokanthera under Carissa, especially as the plants belonging to these genera show great differences in architecture (Hallé & Oldeman 1970; Hallé, Oldeman & Tomlinson, 1978), but he sinks several genera maintained by Pichon, e.g.  Ervatamia under Tabernaemontana (1976).