Senna spinescens var. spinescens

  • Title

    Senna spinescens var. spinescens

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna spinescens (Hoffmanns. ex Vogel) H.S.Irwin & Barneby var. spinescens

  • Description

    53a. Senna spinescens (Vogel) Irwin & Barneby var. spinescens. Cassia spinescens Vogel, 1837, 11. cc., sens, strict.—"Hrb. W[illdenov.] 7960 . .. Hbt. In Brasilia pr. Bahia."—Holotypus, collected by Friedrich Wilhelm Sieber, probably on the lower Amazon in Para, B (hb. Willd. 7960)! = F Neg. 1748.

    Cassia secedens Ducke, Arch. Bot. Jard. Rio de Janeiro 3: 113. 1922.—. . ad margines in- undatos fluvii Xingu inferioris affluentis Tucuruhy prope locum Victoria, 5-8-1918, [RB] n. 17.164, et in palude prope Gurupa, 10-8-1918, [RB] n. 17.191; l[egit] A. Ducke."—Lectoholotypus, Ducke in RB 17164, RB; isotypi, G, P! paratypi Ducke in RB 17191, G!

    Characters as given in key; vascular bundles of mature stems separating (always?) into independent ropes.—Collections: 18.

    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.—Retama conespina (Peru).

    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.