Senna australis (Vell.) 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
Lectoholotypus, the cited plate!
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Synonyms
Cassia australis Vell., Cassia appendiculata Vogel
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Description
Species Description - Crookedly erect or diffusely ascending, amply leafy shrubs at anthesis 1-4 m, with obtusely angulate hornotinous branchlets, the young stems, lf-stalks, margins and dorsal face (or dorsal venation) of lfts and all axes of inflorescence pilosulous with rusty ascending hairs up to 0.4-0.85 mm, the foliage bicolored, the firmly chartaceous lfts lustrous olivaceous drying brown above, paler beneath, the inflorescence of simple racemes axillary to fully developed distal lvs either immersed in foliage or in age shortly exserted. Stipules foliaceous persistent deflexed against stem, very obliquely incurved- semicordate 12-27 x 5-15 mm, at base broadly bluntly auriculate amplexicaul, at apex acuminate-caudate, the blades radially venulose from point of attachment and then reticulate like lfts. Lvs 10-18 cm; petiole including little differentiated pulvinus (1-) 1.5-3(-3.5) cm, at middle (1-) 1.2-2 mm diam, rounded dorsally, openly shallow-sulcate ventrally; rachis 4-8.5 cm; glands (often eaten) between all pairs of lfts sessile or shortly stipitate, in profile 1.4-2.3 mm, the stipe when present glabrous, the ovate acute or subulate-ellipsoid body 0.6-1 mm diam; pulvinules (2.5-)3-4.5 mm, densely pilosulous; lfts 3-5, of most lvs exactly 4 pairs, accrescent upward, the blades broadly obovate from inequilaterally rounded to subcordate base, at apex very obtuse (sometimes minutely mucronulate) or openly emarginate, the distal pair 4.5-8.5 x (2.8-)3-4.7 cm, 1.3-1.8(-2) times as long as wide, the margins revolute, the straight centric midrib immersed above, cariniform beneath, the 7-10 pairs of camptodrome secondary nerves and subsequent reticulation prominulous on both faces, sometimes more emphatic beneath. Peduncles stout (0.6-)1.5-6 cm; racemes ±(5-)10-25-fld, the axis becoming (1.5-)2-12 cm; bracts caducous from below young fl-buds, firm ovate-acuminate 3-5 mm; pedicels at and following anthesis 1.5-3 cm, subtended laterally at base by l(-2) sessile or stipitate fusiform-ellipsoid or ovoid glands 1.5-3 mm; fl-buds obliquely obovoid puberulent at base or over the surface of the small exterior sepals, the inner sepals glabrous dorsally, ciliolate; sepals firm, brownish or livid, obovate-suborbicular concave, very unequal, the smallest exterior (abaxial) 4.5-7 mm, the largest interior one 12-16 mm; petals and androecium of C. velutina, except the filaments glabrous; style filiform straight 4-7 x 0.3-0.4 mm. Pod usually ascending and arched outward, the stipe 3-5 mm, the body narrowly linear, ±15-20 (fide Bentham, -25) x ±0.5 cm, compressed-quadrangular, stoutly keeled by the undulately constricted sutures and by a prominent rib running the length of the rufous-pilosulous valves, the interseminal septa ±6 mm apart forming locules longer than wide; ripe seeds not seen, but apparently quite similar in attitude and form to those of C. velutina.—Collections: 24.
Distribution and Ecology - Thickets in restinga below 30 m, and perhaps also in the foothills back from the ocean, scattered along the coastal plain of s.-e. Brazil between extreme s. Bahia (near Alcobaga) and s.-w. Rio de Janeiro.—Fl. XII-IV(-VIII).
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Discussion
Senna australis is the coastal analogue of interior S. velutina, readily distinguished by ecology and dispersal but only precariously separated in morphological terms by the broader, more simply venose, less pubescent leaflets, always lustrous and glabrous above, and the dorsally glabrous inner sepals. The pod, said by Bentham to be glabrous, but pubescent in all modern collections, may be on the average a trifle broader than that of S. velutina, but is structurally identical, as are the perianths and androecia. The material of S. australis that we have seen is virtually monomorphic and shows no sign of that variation in development of the always foliaceous amplexicaul stipules which is a feature of kindred S. velutina. In abandoning for this species the name Cassia appendiculata, used by Bentham, we follow Burkart (1957, l.c.) and the Code. The supposed obstacle to C. australis Veil, is merely the later homonym C. australis Sims, a taxonomic synonym of C. odorata Morris (cf. Symon, 1966, p. 102). Although no authentic specimen of C. australis Veil, is known to survive, its identity has been plainly known to all students of Cassia through the vividly exact portrait in Vellozo’s leones.
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Distribution
Bahia Brazil South America| Rio de Janeiro Brazil South America|