Monographs Details: Psychotria amplectens Benth.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Description:Distribution and Ecology - Distribution. Brazil, southwestern Venezuela, and Suriname. SURINAME. In sylvis savann. prope kamp 19, fluv. Sipaliwini superior, 15 Feb 1936, H. E. Rombouts 470 (type of Psychotria romboutsii Brem.). VENEZUELA. Amazonas: forest along Río Yatua at base of Cerro Arauicaua, alt 100 m, 10 Apr 1970, Steyermark & Bunting 102510; Mavaca, Alto Orinoco, Jan 1970, Aristeguieta & Lizot 7407. BRAZIL. Amazonas: Rio Acarí, Proctor Cooper III 2; in vicinibus Barra, Prov Rio Negro, Dec-Mar 1850-51, Spruce s n; Barra (Manaus), Mar 1851, Spruce 1176 (type of Psychotria paradoxa M. Arg.); Manaus-Itacoatiara highway, Rio Urubu, 4 Apr 1967, Prance, Pena, Forero, Ramos & Monteiro 4770. Pará: 1871, Derby s n. Terr. Rondonia: basin of Rio Madeira, Rio Bananeiras at crossing of road Guajará-Mirim to Abuña, 5 Aug 1968, Prance, Forera, Wrigley, Ramos & Farias 6779.

Discussion:

Psychotria paradoxa M.-Arg., Mart. FI. Bras. 6(5): 313. 1881.

Psychotria romboutsii Brem., Rec. Trav. Bot. Neerl. 33: 712. 1936; Meded. Bot. Mus. Herb. Rijks Univ. Utrecht 35: 712. 1936.

Type. Rio Branco, Brazil, Robert Schomburgk 879.

It has not been possible to maintain Psychotria paradoxa and P. romboutsii as distinct from P. amplectens. Bremekamp (Rec. Trav. Bot. Néerl. 33: 712-3. 1936) emphasized the importance of the differences in length of internodes of the inflorescence between P. romboutsii and P. paradoxa, namely, that in P. romboutsii the upper internodes of the inflorescence are 2-3 mm long and shorter than the basal internodes, which are 2.5-5 mm long, whereas in P. paradoxa the internodes are stated to increase in length gradually toward the periphery. However, examination of an isotype collection of P. paradoxa at NY as well as the photo of the type at K does not bear out Bremekamp’s observations, as both the photo and the Spruce specimen shows the upper internodes chiefly shorter than or nearly equaling the lower internodes, which range from 7-9 mm, while the upper internodes are 4-6 mm long.

Considerable variation is shown by P. amplectens, P. paradoxa, and P. romboutsii in bract length, presence or absence of interior calycine glands, and length of the internodes of a branch of the inflorescence. Müller-Argoviensis described P. paradoxa from a specimen without flower or fruit, although the photo of the Spruce 1176 specimen in the Delessert Herb, at G shows a fruiting plant with elongated bracts and the internodes close together. M.-Argoviensis stated that the internodes were thus: “ramorum internodiis infima 5-7 mm longa, sequentia gradatim longiora.” However, the specimen of Prance et al 4770, taken not far from the type locality at Manaus, shows only crowded internodes in the fruiting state (as does the photo of the type of P. paradoxa) and successive internodes between the remains of the ovaries are successively shorter rather than “longiora” as indicated by M.-Argoviensis. This is apparent not only in the specimen of Prance et al 4770, but equally evident in other collections assigned to either P. amplectens or P. romboutsii.

The presence of calycine glands was stated by Bremekamp in his description of P. romboutsii. These are also present in the collection of Steyermark & Bunting 102510 from Amazonas, Venezuela, which has a corolla length of 5.5-6 mm, attaining a length described for P. romboutsii. However, the length of the bracts in the Steyermark & Bunting specimen vary from 3-5 mm long on some branches to 5-11 mm long on others and indicate the unreliability of bract length.

Since I have been unable to correlate bract length, internode length, and presence or absence of calycine glands between the taxa under consideration, I have taken up the oldest name, Psychotria amplectens Benth. for this group of species. Although Bentham described the flowers as tetramerous, an examination of the type collection from K shows five corolla lobes.

Distribution:Brazil South America| Venezuela South America| Suriname South America|