Monographs Details: Senna spinescens (Hoffmanns. ex Vogel) H.S.Irwin & Barneby var. spinescens
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 1: 1-454.
Synonyms:Cassia spinescens Hoffmanns. ex Vogel, Cassia secedens Ducke
Description:Variety Description - Characters as given in key [Key: "Lfts glabrous above; sepals strongly heteromorphic, the inner ones (mostly glabrate, rarely velutinous) 11-15 x (5-)6-12 mm; longest anther (excluding beak) 7.5-13.5 mm; style usually less than 1, rarely up to 2.5 mm, ±0.4 mm diam; high-climbing vines, widely dispersed in Amazon and Orinoco basins; s.-w. Costa Rica."]; vascular bundles of mature stems, serparating (always?) into independent ropes--Collections: 18.

Dispersal - River banks, lake-shores and lowland swamp forest or igapo, 5-175 m, discontinuously widespread and either rare or inaccessible (therefore overlooked), along the main streams and major affluents of the Orinoco and Amazon rivers in Venezuela (s.-w. Amazonas, w. Bolivar, s.-e. Apure, Delta Amacuro), Peru (Loreto), Brazil (upper Solimoes and Madeira basins in Amazonas and Rondonia, middle Araguaia basin in Goias and lower Amazonia in Para and Amapa) and adjacent Bolivia (Pando); remotely disjunct in s.-w. Costa Rica (Golfo Dulce, Puntarenas); described, probably mistakenly, from Bahia, whence there are no confirming records.—Fl. primarily IX-IV, intermittently through the year.

Discussion:All specimens of var. spinescens that we have seen from stations peripheral to its whole South American range, in Venezuela, Peru, Rondonia, Goias and lower Brazilian Amazonia, are alike in having highly heteromorphic sepals, the outer more or less pilosulous, the inner glabrous and about 9-12 mm wide. About Sao Paulo de Olivença on the Solimoes and Jandiatuba rivers in western Amazonas, Brazil, otherwise identical plants (Krukoff 8974, Ducke 1504, Mori & Prance 9143) have all sepals golden-strigulose and the inner ones relatively narrow (12-15 x 5-6 mm). The vesture of the calyx might suggest transition to var. schultesiana, but foliage and androecium are in no way different from those of typical var. spinescens. The disjunct Costa Rican plant appears wholly typical.
Distribution:Amazonas Venezuela South America| Bolívar Venezuela South America| Apure Venezuela South America| Delta Amacuro Venezuela South America| Loreto Peru South America| Amazonas Brazil South America| Rondônia Brazil South America| Goiás Brazil South America| Pará Brazil South America| Amapá Brazil South America| Pando Bolivia South America|

Common Names:Retama conespina