I he circumscription of the genus Cladium as adopted by Bentham (1883), Pax (1887), Clarke (1908), and also recently by Kukenthal (1942), in his monographic treatment, has often been criticized and with good reason, for it covers species so heterogeneous that they can not be considered congeneric. Cladium was published as a monotypic genus based on C. jamaicense Crantz from the West Indies (Browne, 1756; Crantz, 1766). After Brown (1810) had extended it considerably by the inclusion of a number of Australian species, several authors of the last century restricted it again to the immediate allies of ~ C. jamaicense. I'or the other species some new genera were created, such as Machaerina Vahl (1806), Baumea and Vincentia Gaudich. (1829), Chapelliera Nees (1834), which were reduced once more to sections or subgenera of Cladium by Bentham and his followers. This reduction, however, was neither accepted by Palla (1902), who on morphological and anatomical grounds reinstated Baumea as a separate genus, nor by Staff (1914), who transferred a number of Malaysian Cladia to Vincentia, with the remark that the West Indian Machaerina approaches so closely to Vincentia that its claim to generic rank might be questioned.