Monographs Details: Rhynchosia
Authority: Grear, John W. 1978. A revision of the New World species of Rhynchosia (Leguminosae-Faboideae). Mem. New York Bot. Gard. 31 (1): 1-168.
Scientific Name:Rhynchosia
Description:Genus Description - Perennial herbs, lianas or subshrubs, erect or ascending, twining, procumbent or prostrate. Rootstocks napiform, fusiform or irregularly club-shaped. Stems terete to angular and striate, simple or diffuse-branched. Stipules persistent or cauducous, striate, free. Leaves long-petiolate or subsessile, unifoliolate or pinnately trifoliolate, the leaflets very diverse in size and form, resin-dotted on both surfaces or sometimes only below; stipels small,when present. Inflorescences racemose, axillary, the flowers lax or congested, rarely solitary. Bracts small, striate, persistent or cauducous, bracteoles lacking. Corolla papilionaceous, usually yellow but often striped or flushed purple or reddish-brown; standard usually obovate with two inflexed auricles at the base and the claw cupulate; wings narrowly oblong, uniariculate, the claw attenuate; keel petals falcate and broader, slightly incurved at apex, laterally saccate, claw attenuate. Calyx campanulate with five long lobes or tubuliform-campanulate with short lobes, the two vexillar lobes connate. Stamens 10, diadelphous, the vexillar stamen free; anthers uniform. Ovary sessile to subsessile, densely villous, biovulate (often uniovulate); style filiform and glabrous, the stigma subcapitate. Fruits 2-valved, beaked and variable in shape from ovate- or oblong-elliptic to falcate or dumbbellshaped; usually compressed, pubescent and gland-dotted. Seeds usually two (rarely one), suborbicular to ovate-reniform, red and brown to black and mottled or bicolored red and black, lustrous, with a whitish strophiole, which is thick and prominent or reduced to a thin membrane covering the hilum; hilum lateral, ovoid to elongate.

Discussion:Type species: R. volubilis Loureiro. Dolicholus Medik, Vorl. Churpf. Phys.-Okon. Ges. 2: 354. 1787, nomen rejiciendum. Type species: D. flavus Medik., nom. illegit. (Dolichos minimus Linnaeus). Cylista Aiton, Hort. Kew. ed. 1, 3: 36, 512. 1789, nomen rejiciendum. Type species: C. villosa Ait., = R. hirta (Andrews) Meikle & Verdcourt. Arcyphyllum Ell., Jour. Acad. Phila. 1: 371. 1818. Austerium Poit. ex DC., Prodr. 2: 385. nomen nudum. Polytropia Presl, Symb. Bot. 21, t. 13. 1831. Cyanospermum Wight & Am., Prodr. 1: 259. 1834. Nomismia Wight & Arn., Prodr. 1: 236. 1834. Pitcheria Nutt., Jour. Acad. Phila. 7: 93. 1834. Chrysoscias E. Meyer, Comm. Pl. Afr. Aust. 1: 139. 1836. Copisma E. Meyer, Comm. Pl. Afr. Aust. 1: 132. 1836. Hidrosia E. Meyer, Comm. Pl. Afr. Aust. 1: 89. 1836. Orthodanum E. Meyer, Comm. Pl. Afr. Aust. 1: 131. 1836. Rynchosia J. Macfadyen, Fl. Jam. 1: 275. 1837. Chrysonias Benth., Ann. Wien. Mus. 2: 114. 1839. Phyllomatia Benth., Ann. Wien. Mus. 2: 113. 1839. Ptychocentrum Benth., Ann. Wien. Mus. 2: 113. 1839. Phaseolus subg. Rhynchosia Eaton & Wright, N. Amer. Bot. 353. 1840. Sigmodostyles Meissn., Hook. Lond. Jour. Bot. 2: 93. 1843. Walpersia Meissn. ex Krauss, Flora 27: 357. 1844. Rhinchosia Zoll. & Mor., Natuur-en Geneesk. Arch. Nederl. Indie 3: 78. 1846. Stipellaria Klotz., Schomb. Faun. Fl. Brit. Gui. 3: 1203. 1848, nomen nudum. Hydrosia A. Juss., Orbigny: Dict. Hist. Nat. 7: 270. 1849. Leycephyllum Piper, Jour. Wash. Acad. 14: 363. 1924. Leucopterum Small, Man. S. E. Fl. 713. 1933. The type of the genus is Rhynchosia volubilis Loureiro, an Old World species which has a wide range in southeast Asia, Indonesia, the Phillipines and southern Japan and Korea. The traditional division of the genus in the New World into two sections is retained in this treatment. In addition, it is believed that further subdivision into species groups, or series, is desirable. However, formal nomenclature and typification for the series is being withheld until much more is known about the variability of the genus throughout its entire range. Characters that define the series are included in the key. Four series are recognized here in section Copisma and two in section Arcyphyllum.