Senna angulata (Vogel) H.S.Irwin & Barneby
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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. angulata indicatur.
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Synonyms
Cassia angulata Vogel
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Description
Species Description - Habit and adult stature little known, sometimes fruticose from 2 m and sarmentose to 10 m, the annotinous branchlets varying from minutely densely subappressed-puberulent to densely pilosulous with subretrorse hairs up to 0.2-0.7 mm, the foliage bicolored, the submembranous lfts dark green or (often) purplish- brown and either glabrous or puberulent above, paler and either strigulose or densely pilosulous beneath, the inflorescence thyrsiform-paniculate, the racemes axillary to developed (but distally smaller) lvs, the fls shortly exserted. Stipules setiform or linear-falciform 7-14 x 0.3-1 mm, deciduous before the lf. Lvs (disregarding distal reduced ones) 5-13 cm; petiole including scarcely differentiated pulvinus 15-35(-40) mm, at middle 0.5-0.9(-l) mm diam, shallowly open-sulcate ventrally; rachis 4-9(-ll) mm, much shorter than petiole; gland 1 between proximal pair of pulvinules, sessile or stipitate, including the glabrous or pilosulous stipe 1-3 mm tall, the body plumply ovoid to lance-ellipsoid; pulvinules (measured to abaxial base of blade) 1.5-2.7(-3.5) mm; distal pair of lfts asymmetrically ovate or lance-elliptic obtuse, emarginate, or shortly bluntly acuminate, 3-8 x (1.2-) 1.6-2.8(-3.1) cm, 1.7-3(-3.3) times longer than wide, the entire margin subrevolute, the straight or slightly incurved midrib giving rise on each side to 8-12(-14) major camptodrome secondary veins either faintly raised or immersed above, beneath finely prominulous, the tertiary venulation faint, the proximal pair of lfts ±1/3 shorter, commonly proportionately broader. Peduncles together with raceme-axis 2-6.5 cm; racemes (4-)6-12-fld; bracts sepaloid, yellowish when fresh becoming brownish, elliptic or ovate-elliptic 8.5-15 mm, cymbiform, in profile ±2-3.5 mm wide, persistent into full anthesis; pedicels 18-32(-40) mm, compressed-quadrangular; sepals submembranous, yellow or red-striped or -flecked, ovate to elliptic-oblong or oblong-oblanceolate obtuse, the longer inner ones up to 11-15.5(-17) mm, dorsally glabrous or sometimes proximally puberulent; petals puberulent dorsally along the veins, the larger ones broadly obovate-flabellate obtuse or emarginate up to 24-33.5 mm, one abaxial one oblique; filaments subappressed-pilosulous, those of 3 long abaxial perfect stamens 4-6.5 mm, of the 4 median ones 1.5-2.2 mm; thecae glabrous, of the 3 long stamens 9-13.5 mm contracted into a porrect beak 1-1.8 mm, of the 4 median 6-9.5 mm, their divaricate beak 0.5-0.8 mm, the terminal pores of all stamens either confluent or separated by a slender septum; ovary densely pilosulous, the abruptly incurved glabrescent style ±1-1.5 mm, the stigmatic cavity 0.35-0.45 mm diam; ovules 112-160. Pod pendulous stipitate, the stipe 5-6 mm, the linear-cylindric body ±17-20 x 0.8-1.6 cm, abruptly contracted at both ends, the valves becoming pale brown papery smooth, veinless or almost so, dehiscent through the ventral suture; seeds 2-seriate, compressed-obovoid 4.8-7 mm, the testa lustrous dark brown or almost black, exareolate.
Variety Key - Key to the Varieties of S. angulata 1. Annotinous branchlets glabrate or puberulent, green or brownish; along the Atlantic coast from s. Bahia to Parana. 39a. var. miscadena (p. 178). 1. Annotinous branchlets densely pilose-subvelutinous with spreading-retrorse hairs; local on and near the Rio Doce-Rio Sao Francisco divide in s.-centr. Minas Gerais. 39b. var. angulata (p. 178).
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Discussion
In habit and foliage S. angulata much resembles the remotely allopatric S. chrysocarpa and S. tapajozensis, differing from both, however, in the colored sepaloid bracts which persist into anthesis. Strongly heteromorphic sets 01 fertile stamens are common to S. angulata and S. tapajozensis, an early collection of which (Spruce 1775 from Manaus, K!) was actually referred by Bentham simultaneously (1870, pp. 101, 102) to Cassia angulata and a variety of C. chrysocarpa. Senna tapajozensis not only lacks the colored bracts of S. angulata but differs further in a coarsely venulose pod, substantially more numerous ovules (±180-220, not 112-160) and dispersal confined to the Amazonian Hylaea. As in most Bacillares of which we have many samples, the foliage of S. angulata varies considerably in amplitude and outline of leaflets, but we regard this type of variation as taxonomically insignificant. There seems to be, however, a racially significant variation in pubescence, the populations along the coast and outer Atlantic foothills being only sparsely puberulent whereas those isolated at greater elevations in southern Sa. do Espinha^o in Minas Gerais have densely velvety-pilose stems. Names for these two aspects of the species were provided by Vogel and are maintained here in genus Senna.