Monographs Details: Forsteronia guyanensis Müll.Arg.
Authority: Maguire, Bassett & Wurdack, John J. 1958. The botany of the Guayana Highland--Part III. Mem. New York Bot. Gard. 10: 1-156.
Family:Apocynaceae
Discussion:This collection has a corymbose inflorescence, as described for F. brevifolia Mgf. by Woodson in the key to the species of Forsteronia (Ann. Missouri Bot, Gard. 22: 155. 1935). It seems, however, that F. brevifolia should be regarded as merely a synonym of F. guyanensis. The type was collected along the Tocantins, Amazonas, Brazil. Ricardo de Leinos Froes 21471 (Mata do Igarape do Massabo, Cabary, Rio Negro, Amazonas, Brazil) agrees very well with the photo of the type of F. brcrifolia, but also ties up with Wurdack d: Monachino 39733 and some of the Guiana material of F. guynncnsis. The NYBG specimens of F1418 and F2113 from British Guiana, cited as F. gracilis (Benth.) Muell.-Arg. in Bull. Torrey Club 75: 554 (1!>48), are of F. guyanensis. Killip & Smith 30151 (Manaos, Amazonas, Brazil), cited by Woodson as F. riedeln Muell.-Arg., and Ducke 1980 and 420 (Manaos), which are similar to the Killip & Smith clolection, are probably also conspecific with F. guyanensis. The leaves of these specimens are not altogether eglandular; there are small glands or gland-scars at the base of some leaf-blades. It is suspected that glandulosity is a somewhat variable character in F. guyanensis, as are the size and shape of the sepals, the size of the corolla, and the kind of indumentum. In reference to F. riedeln, Woodson states (p. 177) that the type specimen Avas collected by Riedel and cited as from Serra d' Estrella. "It will not be surprising, therefore, if the specimens cited from Amazonas may eventually be proved to represent a distinct species."