Monographs Details: Psychotria capitata subsp. amplifolia (Raeusch.) Steyerm.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Discussion:

Psychotria amplifolia Raeusch., Nom. Ed. 3. 56. 1797.

Nonatelia violacea Aubl., Pl. Guian. 1: 188. pl. 73. 1775.

Oribasia violacea (Aubl.) Gmel., Syst. Nat. 367. 1791.

Palicourea violacea (Aubl.) A. Rich., Mem. sur les Rub. 95. 1829.

Naletonia violacea (Aubl.) Brem., Rec. Trav. Bot. Neerl. 31: 285. 1934.

Psychotria violacea Willd., Sp. PI. 1: 966. 1797, not Psychotria violacea Aubl. 1775.

In segregating Naletonia as a genus distinct from other members of the Psycho-trieae, Bremekamp (Rec. Trav. Bot. Neerl. 31: 284. 1934) emphasized as of greatest significance the characters of imbricate aestivation of the corolla, tetramerous flowers, and entire or notched, large, deciduous stipules. As regards imbricate aestivation, I have carefully dissected corolla buds from numerous collections and all show a typical valvate aestivation in which the margins of the corolla lobes join one another at their edges without any overlapping. Bremekamp may have been misled by the appearance of the dried corolla bud, which, when pressed, shows the broader lower part of the corolla lobe folded or pressed over part of the surface of the adjacent lobe, producing a superficial impression of being imbricate. However, upon dissection, this is found to be nothing more than the manner in which the pressed corolla lobe is folded over, as, upon boiling of the flower, the edges of each adjacent corolla lobe are found to be united along their margins and not overlapping one another. Seen from above, a bud would be cross-shaped in the tetramerous flowers.

The character of tetramerous flowers can be dismissed as of little or no generic value, since tetramerous flowers occur frequently throughout taxa of the genus Psychotria, and many species exhibit both tetramerous and pentamerous flowers on the same inflorescence. Of the specimens cited above, Fanshawe 2037 from British Guiana, shows flowers with both 4-5 stamens and 4-5 corolla lobes in the same inflorescence. Although the flowers are usually tetramerous in subsp amplifolia, both teramerous and pentamerous flowers occur throughout the taxon P. capitata and subsp inundata var inundata and var roraimensis. The character of the stipules in subsp amplifolia is the most distinctive one to separate it from typical P. capitata and subsp inundata, but this character alone is not sufficient to maintain Naletonia as a genus, and, moreover, a great diversity of stipule sizes and shapes are to be found throughout Psychotria. Actually, the degree of stipule notching and bifurcation varies in subsp amplifolia from somewhat bifid to a bifurcation of 1/4 to 1/3 distance down the length of the stipule. A similar variation occurs in some specimens of P. capitata subsp capitata var capitata from Peru, such as in Schunke 427 with stipules lobed only 1/3 to 1/2 instead of nearly to their bases as in other collections of subsp capitata var capitata.

Although the bracts of the inflorescence in subsp amplifolia are usually longer and broader than those of subsp inundata, they are similar to those of subsp capitata var capitata. The inflorescence of subsp amplifolia approaches or matches the size and number of axes found in subsp inundata. The inflorescence of subsp amplifolia is often oblong or elongated, while that in subsp capitata and subsp inundata may average broader than high to subhemispheric, but there is no correlation in this character, and the same general shape and size of the inflorescence may be found in widely separated areas. The collections of Holt & Blake 797 from Amazonas, Venezuela, have deeply parted stipules typical of subsp inundata but small inflorescences matched by a Nicaraguan collection (Proctor, Jones & Facey 26943) of subsp amplifolia with only suberose stipules.

Bremekamp remarked that the ovary of Nonatelia violacea is “in reality 2-celled” instead of 5-celled as described by Aublet. Dissection of numerous flowers of a collection from French Guiana by Halle 485 shows that the ovary varies from 2-3-celled, the disk being 2- or 3-parted.

In short, a comparison and evaluation of the various characters noted for Naletonia violacea (Aubl.) Brem. lead the present author to conclude that it must be considered as part of the variation of the Psychotria capitata group, and regarded in the status of subspecies. As indicated above, the major distinctive character is that of the stipule, and even this character intergrades in some specimens within the range.

The material examined from Central America had been previously identified as P. capitata, but all the specimens show entire to shortly bifid stipules, characteristic of the subsp amplifolia.