Rubiaceae of the New World

By Piero Delprete and Rocio Cortés
 

UNCARIA Schreber

Uncaria guianensis             Photo C. Gracie Saul, French Guiana

Uncaria guianensis      Photo S. Mori             El Palmar, Venezuela

Synonyms: Ourouparia Aublet; Restiaria Loureiro, non Restiaria O. Kuntze; Uncinaria C. L. Reichenbach (nomen)

Woody vines, lianas or scandent shrubs; raphides absent; axillary thorns strongly recurved (cat claw-shaped). Stipules interpetiolar, free at base, deltoid, obovate or cordate, persistent or subcaducous. Leaves opposite, long or short-petiolate; blades ovate, elliptic, obovate or oblong, stiffly chartaceous, papyraceous, thinly to thickly coriaceous; foliar pellucid glands absent; domatia sparse tufts of hairs, hairy-pockets, tuft-pits or absent. Inflorescence terminal, frondose, paniculate, with branches terminating in globose few- to many-flowered heads. Flowers bisexual, protandrous, or functionally unisexual (staminate and pistillate flowers on separate individuals). Calyx funnel-shaped or short tubular, persistent; lobes 4 to 6, narrowly ovate, ovate or broadly ovate, minute. Calycophylls absent. Corolla hypocrateriform or narrowly infundibuliform, actinomorphic, white to cream-white or yellow when young, turning red in later stages; tube externally retrorsely puberulous, villous or sericeous, internally glabrous or sericeous; without a pubescent ring inside; orifice annular thickening absent; lobes 4 to 6, imbricate (tube non reduplicate), narrowly ovate, ovate, rounded or oblong, margin entire, rounded at apex. Stamens alternate to the corolla lobes, partially exserted (only tips exserted); anthers elongate, with pointed extension at base, with acuminate extensions at apex, dehiscing by longitudinal slits, dorsifixed near the base; filaments attached near the mouth of the corolla tube, free at base, short (anthers subsessil), equal, glabrous. Style exserted well beyond the corolla, terete, not fleshy, capitate, glabrous; lobes absent, stigmatic surface located at style apex. Ovary inferior; 2-locular, ovoid; placentation axile, placenta peltate to the entire lenght of the septum, ovules many per locule. Fruit a septicidal capsule, dehiscing basipetally, the valves not splitting at apex, thinly woody. Seeds ascendingly imbricate, medium or large, laterally compressed, irregurlarly narrowly oblong to fusiform in outline; wings bipolar, margin entire.

Geographic distribution: Northern Central America (up to southern Mexico), southern Central America, northern Chocó area, Magdalena-Llanos area, Napo-Marañón drainage, southwestern Amazon Basin, western Amazon Basin, Guayana Shield, central Amazon basin, eastern Amazon basin, Brazilian planalto. A pantropical genus with about 35 species; 2 of which occuring in the Neotropics, and reputed of important medicinal properties.

Number of species: 2.

References: J. A. Steyermark, Uncaria. Fl. Venezuela 1: 32–39. 1974; L. Andersson, Uncaria. Fl. Ecuador 50: 106–109. 1994; B. Boom & P. Delprete, Uncaria. In: S. Mori et al., Pl. Centr. Fr. Guiana 2: xxx-xxx (accepted).