Monographs Details: Psychotria
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Scientific Name:Psychotria
Discussion:

Grumilea Gaertn., Fruct. 1: 138. pl. 1, f 7. 1788.

Mapouria Aubl., Pl. Guian. 1: 175. pl. 67. 1775.

Ronabea Aubl., Pl. Guian. 1: 154. pl. 59. 1775.

Cephaelis Sw., Prod. Veg. Ind. Occ. 45. 1788.

Carapichea Aubl., Pl. Guian. 1: 167. pl. 64. 1775.

Tapogomea Aubl., Pl. Guian. 1: 357. pl. 60 and 63. 1775.

Petagomea Brem., Meded. Bot. Mus. Herb. Utrecht 11: 295. 1934.

Gamotopea Brem., Meded. Bot. Mus. Herb. Utrecht 11: 293. 1934.

Callicocca Schreb., Gen. 1: 126. 1789.

Evea of authors, not Aubl., PL Guian. 1: 103. pl. 39. 1775, excluding E. guianensis Aubl.

Uragoga L., Gen. PI. ed. 1. 378. n. 64. 1737; Baillon, Adansonia 12: 323. 1879.

Nonatelia Aubl., PI. Guian. 1: 182. pl. 70-75. 1775.

Ipecacuanha Arruda, Diss. 44. 1810; ex St. Hil. PI. Bras. pl. 6. 1824.

Chytropsia Brem., Meded. Bot. Mus. Herb. Utrecht 11: 291. 1934.

Notopleura (Benth.) Brem., Meded. Bot. Mus. Herb. Utrecht 11: 289. 1934.

Naletonia Brem., Meded. Bot. Mus. Herb. Utrecht 11: 284. 1934.

Type. Psychotria asiatica L., Syst. ed. 10. 929. 1759.

A detailed examination of some 300 taxa from the northern half of South America identified as Psychotria, Cephaelis, Mapouria, and other related segregated genera, has convinced the present author that the whole of these taxa must be grouped under one comprehensive genus, Psychotria. In reaching this conclusion, many other species from other parts of South America, Mexico, and Central America, the West Indies, and the Old World tropics have been examined. It should also be noted that similar conclusions have been recently obtained on the African species of Psychotria by Dr. E. Petit [Les Espèces Africaines du Genre Psychotria L. (Rubiaceae)-I Bull. Jard. Bot. Brux. 34: 1-229. 1964.], who was not able to maintain Grumilea, Mapouria, Cephaelis, or Uragoga separate from Psychotria.

The present author’s conclusions have been reached as the result of the following considerations: (1) Cephaelis is an artificial concept which has been maintained for those species with a strongly contracted inflorescence surrounded by large bracts and with the enclosed individual flowers surrounded by their own bracts and bracteoles. Strictly speaking, this combination of characters would include a relatively few species, but one cannot draw any well-marked line to separate the many variations of combinations of such characters to assign one group to Cephaelis, another to Psychotria, and still others to the various segregates proposed by Bremekamp. Many taxa have an inflorescence subtended by showy colored bracts or with only the outer flowers enclosed by bracts. Within an inflorescence enclosed by colorful enlarged bracts, some of the flowers may not have bracteoles and others may. In short, such taxa fail to meet the arbitrary requirements of a Cephaelis or of a Petagomea in which all the flowers must be enclosed individually by bracts and bracteoles. In some cases, these outer involucral bracts are united into a tube, in others free to the base. In addition, there are inflorescences in which the outer bracts subtend a series of larger bracts on the outer portion of the head of flowers, but, within and toward the center, no bracts may be present. Furthermore, one can observe a series of taxa in which the bracts shift in position from the base of the inflorescence to various higher portions of the axes of the inflorescence. This results in many variations of placement of bracts, in which some taxa possess two or three flowers subtended by one common bract, other taxa with the flowers not subtended, and other stages of bract and flower relationship. The application of a rigid concept, such as Cephaelis, to variation of bract placement within an inflorescence, is inconsistent and unnatural. Many species accepted as Psychotria show a bracteate development surrounding the inflorescence, such as in P. barbiflora, P. lupulina, and P. hoffmannseggiana, while P. polycephala, with a racemose or paniculate inflorescence, has the individual flowers subtended by bracteoles as in Cephaelis. Similarly, in the group of species involving P. altsonii, P. nivea, and P. sandwithiana, although the outermost bracts are strongly united to subtend the head as in many species of Cephaelis, the bracteoles are absent or obsolete, represented by glands or protuberances from the receptacle, thus not conforming to the concept of Cephaelis. Finally, our concept of Cephaelis is subjected to additional pressure in a consideration of the group to which P. uliginosa and P. macrophylla belong, which Bremekamp treated under the segregate genus Notopleura, originally published by Bentham as a section of Psychotria. In this group one finds the gamut of variation of placement and arrangement of the subtending involucral bracts, the outer bracts being either present or suppressed next to the outer flowers, and the bracteoles between the outer and inner parts of the head of flowers being present or absent. (2) In attempting to separate the genera Notopleura and Naletonia from Psychotria, Bremekamp in both instances (Rec. Trav. Bot. Neerl. 31: 285, 289-290. 1934) employed the character of imbricate aestivation of the corolla as an important and significant one. Through careful dissection of abundant material representing the taxa involved in Notopleura, it can be definitely asserted that the corolla lobes are valvate as is the condition throughout Psychotria. Moreover, other characters used by Bremekamp to sustain and separate new genera from Psychotria have been found not to hold or to be unreliable, as will be brought out in the discussion for each of the taxa later on in this treatment. (3) The type species of Psychotria, P. asiatica L., as shown by Petit (Bot. Jard. Bot. Brux. 34: 9-15, 24) belongs, together with P. brownei, actually in the group separated as Mapouria by Bremekamp and, in part by Mueller-Argoviensis. (4) Moreover, Petit’s study of the African species of Psychotria demonstrated the unreliability of the degree of rumination of the albumen to separate Grumilea from Psychotria and Mapouria. Segregate genera of Bremekamp, based on presense or absence of longitudinal fissure of the pyrenes, extent of dorsal ribbing or flattening of pyrenes, furrowing of the endosperm, together with variations of stipules, have been found either lacking characters that do not correlate or else run together in transitional series, of which many taxa are known only from flowering material. Petit, likewise, has rejected (p. 24) the separation of Mapouria, Apomuria, and Psychotria on the basis of seed characters, as employed by Bremekamp.

An attempt has been made in the following treatment, which includes all the species known from Venezuela, the Guianas, Guayana Highland, and Amazonian Brazil, together with related taxa, to classify the neotropical species of Psychotria under two main subgenera: (1) Psychotria, the type species of which, P. asiatica L., proves congeneric with Mapouria, and (2) Heteropsychotria, comprising the main assemblage of species previously assigned to Psychotria, Cephaelis, Uragoga, and segregate genera. Under Heteropsychotria have been indicated sectional and series names. These names have been supplied, despite our present rudimentary knowledge of the entire genus, pending future and more detailed studies of the remainder of the Neotropical species, to show apparent relationships between the taxa presented. However, in many instances, no evident relationships are indicated and in such cases no formal names have been assigned. Also, some sections and series are found to include portions of one or more sections indicated previously by Bentham & Hooker (Gen. PI. 2: 123-125; 127-128. 1873) and Mueller-Argoviensis [Mart. FI. Bras. 6(5): 222-223; 241-427. 1881], In other instances a new name has had to be proposed for the name of the species comprising that group without formally assigning the group a name. Some distinct groups of species, unknown to Bentham, Mueller-Argoviensis, and others, have been found to constitute a distinct new section, such as the Potaroenses.

In connection with the treatment of subgenera, a statement should be made concerning the subgenus Tetramerae (Hiern) Petit (sect Tetramerae Hiern in Oliver, FI. Trop. Afr. 3: 193. 1877) erected by Petit (Bull. Jard. Bot. Brux. 34: 27-28. 1964) and later re-evaluated (Bull. Jard. Bot. Brux. 36: 67. 1966). The subgenus Tetramerae was designated as such by Petit and based on Hiern’s grouping of the species (in Oliver, Fl. Trop. Afr. 3: 193. 1877) to accommodate those taxa from Africa and (subsequently by Bremekamp) from Madagascar having bacterial nodules in the leaves, together with the characters of elongated, narrow, biacuminate stipular teeth, small loose or dense panicles with very small bracts, non-ruminate seeds, and sometimes tetramerous flowers. Although Petit attributed the status of subgenus to Hiern, the latter treated the epithet Tetramerae as a section implied as such along with four others, i e, Paniculatae, Confertiflorae, Bracteatae, and Chasalia, of which the first three (Paniculatae, Confertiflorae, and Bracteatae) were interpreted as sections later by Petit (Bull. Jard. Bot. Brux. 34: 27. 1964) and attributed by Petit to Hiern as sections. Hepper, likewise, in Hutchinson & Dalziel’s FI. W. Trop. Afr. 2: 191. 1963, interpreted Hiern’s treatment of Chasalia in Oliver’s Fl. Trop. Afr. as a section, by Hepper, however, treated in the generic status.

Petit would appear, therefore, to have been the first to establish the epithet Tetramerae Hiern in a subgeneric sense, and I have so interpreted his treatment as a new status. Thus far, no species of the subgenus Tetramerae have been found outside of Africa and Madagascar. However, granted the possibility that an exhaustive future study of Neotropical members of the genus Psychotria may reveal the presence of such bacterial nodules, such a situation would create a reconsideration of the subgeneric status of Tetramerae.

On at least two occasions, Bremekamp (Not. Syst. 16: 45. 1960; Verh. Kon. Ned. Akad. Wetens. II. 54 : 8. 1963) has conceded that the genus Mapouria cannot be legitimately retained apart from Psychotria, since the type species of Psychotria is congeneric with Mapouria. Nevertheless, he suggests that the name Psychotria asiatica L., the type species of the genus, be considered a “nomen confusum,” “parce que . . . comprend des éléments héterogènes,” meriting at some future time the idea of the selection of a new type for the genus. However, as Petit has pointed out (pp 12-13), the definitive limits of Psychotria are not changed, whether one refers to P. asiatica L. as the type species from Asia or as “P. asiatica” from Jamaica (= P. brownei), since the two taxa are sufficiently related to be congeneric. Bremekamp’s suggestion of a “nomen confusum” and selection of a new generic type appears to be unrealistic and unnecessary.