Senna bicapsularis (L.) Roxb.
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Authors
Howard S. Irwin, Rupert C. Barneby
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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.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Typus infra sub var. bicapsulari indicatur.
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Synonyms
Cassia bicapsularis L.
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Description
Species Description - Weakly arborescent shrubs, when free-standing either diffuse or bushy, in brush-woodland, hedges or forest margins sarmentose and the long terete striate hornotinous branches horizontal or obliquely pendulous (the heliotropic peduncles then appearing retroarcuate), the old stems lenticellate, glabrous throughout or the young stems and pulvinules thinly pilsosulous with fine random incurved hairs up to 0.1-0.3 mm, the thick-textured, mildly malodorous foliage dull olivaceous subconcolorous, the axillary racemes either all lateral to primary leafy only ± half the pod’s cavity, each lined with fetid sweetish pulp; seeds plumply compressed-obovoid or semi-obovoid (sometimes distorted by crowding) 3.9-5.1(-5.5) x 2.9-4(-4.3) x ±2 mm, the brown testa usually smooth and lustrous sometimes minutely granular, exareolate.
Variety Key - Key to the Varieties of S. bicapsularis 1. Lfts of mature lvs (disregarding depauperate ones of paniculate inflorescences) mostly or entirely 3-4 pairs, 4-foliolate lvs few or absent; range of the species, but in Ecuador, Peru and Chile only about coastal cities, presumed adventive. 129a. var. bicapsularis (p. 401). 1. Lfts of all lvs exactly 2 pairs (random 3-jugate lfts obviously exceptional); native at low and middle elevations along the Pacific slope of the Andes from extreme s. Ecuador to s. Peru. 129b. var. augusti (p. 403).
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Discussion
Senna bicapsularis of this account is equivalent to Cassia bicapsularis of De Wit (1955), Brenan (1967) and Lasseigne (1980, dissert, ined.) and to Adipera bicapsularis Britton & Rose (1930, excluding the synonym Cassia coluteoides which = S. pendula); following these precedents we abandon Bentham’s comprehensive definition that was stretched to include the species treated above as S. pendula and S. candolleana. Like our predecessors, we stress the short pedicels as the most distinctive feature of S. bicapsularis sens, str., but must point out that the pedicel as described hitherto is actually, like that of S. (ser. Senna) alexandrina, not a simple stalk but actually compounded of a true pedicel and a downwardly attenuate hypanthium which may be either slightly longer or shorter than it. Thus the true pedicel is, by comparison with that of related species, even shorter than has been supposed. The composite structure of the flower-stalk is especially apparent in unfertilized flowers, which disjoint at the plane of junction, and again in the thickened fruiting flower-stalk, where the discontinuity is marked externally at first by a more or less emphatic swelling and later (often but not always) by an incised scar. Intraspecific variation in S. bicapsularis, other than such as is readily attributable to age and environment, is marked only in western South America. Along the Pacific slope of the Andes between southernmost Ecuador and southern Peru there appear to be both truly native and adventive populations of the species, the latter inseparable from their Caribbean kindred, the autochthonous ones differing in their mostly or entirely 4-foliolate leaves. Following Macbride (1943) in this, but not all details of his account, we recognize a var. augusti.