Memoirs of The New York Botanical Garden
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of Vascular Plants of Northeastern United States and adjacent Canada
Details: Psychotria capitata Ruiz & Pav.
Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Psychotria capitata Ruiz & Pav.
This taxon is highly variable. The variations are distinctive in their extremes, but so many intergrading series are present that they have been interpreted here as one taxon with several subspecies and varieties.