Psychotria grandifolia Willd. ex Roem. & Schult., Syst. Veg. 5: 190. 1819.
This is the earliest of the group of the section Oribasa M.-Arg., placed under Psychotria by Müller-Argoviensis in Martius’s Flora Brasiliensis (6(5): 223. 1881), characterized by its usually 5-celled ovary, contrasted with those taxa having 2-celled ovaries and corollas sigmoid-curved or unequally gibbose at the base in section Palicourea, likewise placed by Müller-Argoviensis under Psychotria.
The various taxa treated by Müller-Argoviensis in section Oribasa (Psychotria grandifolia, P. wallisiana, P. megalophylla, P. macrothyrsa, P. amazonica, P. sprucei, and P. cataractarum) involve closely related forms which cannot be maintained as species. Psychotria grandifolia and P. amazonica are alike in having the lower surface and midrib of the leaf blades glabrous, whereas P. sprucei, P. macrophylla, P. macrothyrsa, and P. ulei share the common quality of having the lower surface and midrib of the leaf blade more or less pubescent. Other characters used by M.-Argoviensis to separate the above taxa, such as differences of relative proportions of the length of hypanthium and calyx, degree of divergence of lateral nerves of leaf blades, or shape of hypanthium, have not been found to be trustworthy or stable. The result is a merging of the taxa cited above into one species, which varies in the lower surface and midrib of the leaf blades from pubescence to glabrous.