Senna corymbosa (Lam.) 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
Holotypus, cultivated at Paris from seeds collected by Commerson on Bougainville’s voyage, P-LA! isotypus, P (hb. Poiret.)!—Chamaefistula corymbosa (Lamarck) G. Don, Gen. Hist. Diehl. PL 2: 451. 1832. Cassia falcata Dumont du Courset, Bot. Cult. ed. 2, 6:
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Synonyms
Cassia corymbosa Lam., Chamaefistula corymbosa (Lam.) G.Don, Adipera corymbosa (Lam.) Britton & Rose, Cassia crassifolia Ortega
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Description
Species Description - Erect or, with age and opportunity, sarmentose slender shrubs and treelets at anthesis 0.8-4 m, with terete, finely ribbed greenish-stramineous hornotinous and fuscous-castaneous or nigrescent older (leafless) branches, except for often residually pubescent pulvinules, exceptionally for puberulent sepals and nearly always for strigulose-pilosulous ovary glabrous throughout, the foliage dull pale olivaceous concolorous or almost so, the few-fld racemes at first axillary to and not or scarcely longer than the subtending lf, some later ones often forming a terminal, shortly exserted corymbose panicle. Stipules submembranous, narrowly linear-lanceolate 2-5 x 0.2-0.6(-0.7) mm, pale green turning stramineous and dry, caducous before maturity of associated lf, absent from most mature fl and all fr spms. Lvs 5.5-9.5 cm; petiole slender, including moderately dilated pallid or discolored pulvinus (13-) 15-28 mm, at middle 0.35-0.6(-0.7) mm diam, bluntly 3-ribbed laterally and dorsally, narrowly sulcate ventrally; rachis 6-27 mm, the longer (or only) interfoliolar segment 6-15 mm; gland between proximal pair of lfts stipitate 1.3-2 mm, the ovoid or lance-ellipsoid apiculate or obtuse head 0.25-0.6 mm diam, a depauperate gland sometimes between second (but not the distal) pair; pulvinules (0.8-) 1-2.2 mm; lfts commonly 3 or 2-3, rarely in all lvs exactly 2 pairs, accrescent distally, the distal pair lanceolate, lance- or narrowly oblong- elliptic obtuse mucronulate or apiculate, less often subemarginate or deltately subacute 25-47(-60) x (4.5-)5-12(-14) mm, (3.3-)3.5-5.6(-6.5) times as long as wide, at oblique base varying with increasing breadth from cuneate to rounded, the (mature) margin plane, the midrib and 9-14 pairs of camptodrome (with random intercalary) secondary veins immersed or feebly prominulous on upper face, sharply prominulous beneath/the tertiary venules usually invisible above, always raised beneath, forming a loose reticulum. Racemes 4-15(-18)-fld, the 1 or more expanded fls raised to or beyond level of ascending, obliquely obovoid buds, the axis together with peduncle becoming (1.5-)2-6(-7) cm; bracts submembranous pallid, narrowly lance-subulate 14 x 0.25-0.6 mm, caducous as pedicel begins to elongate; mature pedicels (13-)15-23 mm; hypanthium (not always externally differentiated) vase-shaped (1-)1.2-2 mm; sepals submembranous brownish pale-margined, ovate or elliptic-obovate obtuse not strongly graduated, the outermost 4-6 mm, the largest inner one 6-8.5 mm; petals glabrous short-clawed yellow drying brownish-yellow or stramineous brown-veined, the vexillar one either broadly obovate obtuse or flabellate-obovate emarginate, the rest alike obovate or the 2 abaxial ones narrower and often a trifle longer, nidulating the long stamens, the longest petal (8-)9-14(-16) mm; androecium glabrous, the blade of 3 staminodes elliptic-obovate or oblong-oblanceolate 1.5-2 x 0.7-1.2 mm, the filaments of 4 median stamens 1.8-2.7 mm, of the centric abaxial one (2.5)3.5-6 mm, of the long abaxial pair (5.5-)6.5-9 mm, the anthers of 4 median stamens including obliquely truncate beak 3.6-4.8 x 0.8-1.2 mm, of the long abaxial pair lunately lanceolate from obtuse base including beak 5.2-6.5 x (1-)1.1-1.4 mm, the beak itself 0.5-0.8 mm long, at orifice 0.7-1 mm diam, 2-umbonate adaxially and produced abaxially into a short pollen-cup divided by a slender vertical septum, the centric abaxial anther scarcely narrower than its neighbors, fertile; ovary thinly strigulose or pilosulous laterally, the sutures glabrous, or glabrous overall; style gently incurved and often a trifle dilated distally (2-)2.2-3 x 0.2-0.3(-0.4) mm, the stigma obliquely in- trorse; ovules 34-50. Pod essentially pendulous, the stipe 3-5 mm, the fully fertilized body cylindric or obscurely quadrangular-compressed, straight or a trifle incurved 7.512 x 0.6-0.9(-l) cm (in fact often sterile toward base or at random intervals upward, becoming at maturity shorter or variably misshapen), the smooth green glabrous or early glabrate valves becoming papery brownish-stramineous or cas- taneous, separating into 2 layers, the endocarp thinly pulpy, the uniseriate seed- locules occupying the full width of the cavity and 2-3 mm long; seeds transverse, turned with broader faces to the septa, plumply obovoid or oblong-ellipsoid 4.5-5.3 x 3-3.6 mm, the testa dull brown or lustrous castaneous, exareolate; n = 14.—Collections: 42.
Distribution and Ecology - Thickets, brushy stream and river banks below 150 m, native along the lower Parana and Uruguay rivers, in the Mesopotamia of n.-e. Argentina and adjoining Uruguay s.-ward from 28°S in Corrientes to the Plate estuary, thence n. and s. along the coast into Rio Grande do Sul, Brazil and as far as Miramar in Buenos Aires; foothill streambeds and disturbed places up to 450(-?) m in Tucuman and Cordoba, Argentina, long since established and appearing native; widely naturalized in the Gulf States of s.-e. United States (cf. Isely, l.c.); cultivated and casually escaping in waste places and hedges in warm temperate w. Europe and South Africa, and grown in many botanical gardens (under protection n.-ward) in both Old and New worlds.—Fl. in Argentina and Uruguay XI-V.
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Discussion
Since its introduction to Europe by Philibert Commerson two centuries ago S. corymbosa has been in continuous cultivation. A handsome, free-flowering shrub easily propagated either by seed or cuttings, it has been widely dispersed among botanical gardens in tropical and warm temperate countries and in places has become extensively naturalized. In southern United States it is known to endure short periods of light frost without damage, and could be more widely used as an ornamental, its late-summer floral display being especially welcome. The primitive range of S. corymbosa, unknowable in sure detail, is likely to have been Argentine Mesopotamia, southern Uruguay, the Plate estuary and the neighboring Atlantic shore and coastal lowlands. The populations in Tucuman and Cordoba, like most of the few known ones in Rio Grande do Sul, are probably secondary. The close relationship of S. corymbosa is to S. pendula and S. hilariana, vicariant northward, which differ collectively in the more numerous leaflets, in the first case broader and in the second smaller. An apparently constant diagnostic feature in the flower of S. corymbosa is the fertile abaxial anther which, though borne on a somewhat shorter filament, is as long and almost or quite as plump as its fellows on either side, not etiolated and empty of pollen as in kindred species.
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Common Names
Rama negra, sen de campo
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Distribution
Corrientes Argentina South America| Rio Grande do Sul Brazil South America| Buenos Aires Argentina South America| Tucuman Argentina South America| Córdoba Argentina South America| Uruguay South America|