Senna viarum (Little) 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 2: 455-918.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Holotypus, NY! isotypi, K, US!—Cassia velutina (Britton & Killip) Garcia-Barriga & Forero-Gonzalez, Cat. Ilustr. Pl. Cundinamarca 3: 61, fig. 21. 1968; non C. velutina Vogel = Senna velutina (Vogel) Irwin & Barneby.
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Synonyms
Cassia viarum Little, Chamaesenna velutina Britton & Killip, Cassia velutina Vogel
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Description
Species Description - Trees with amply leafy rounded crown, at anthesis (3-)4-15 m, the smooth gray trunk up to ±1-1.5 dm diam, the annotinous stems and lf-stalks densely pilosulous with straight erect or commonly flexuous and ± entangled, pale shining hairs up to (0.3-)0.4-0.8 mm, the pubescence extending outward ± equally densely along the midrib and (especially dorsally) the secondary veins, sometimes also to the intervenium of the lfts, the thin-textured foliage bicolored, the dull olivaceous lfts paler beneath, the glabrescent racemes at first axillary to and shorter than cauline lvs but often distally forming a small exserted panicle. Stipules early deflexed, lanceolate or obliquely ovate-caudate 6-20 x 4-8 mm, the herbaceous blades revolute, finely striate-nerved, pubescent adaxially as well as dorsally, persistent often until fall of lf. Lvs 15-35 cm; petioles including scarcely swollen pulvinus (2-)4.5-8(-9) cm, at middle 1.5-4 mm diam, subterete but very narrowly thick-margined and openly sulcate ventrally; rachis 6-16 cm; petiolar gland 0; pulvinules 3.5-7(-8) mm; lfts 4-6 pairs, accrescent distally but the penultimate longest, the distal pair a little smaller, all broadly lance- or narrowly ovate-acuminate, the largest 7-15 x 2.3-5 cm, 3-4 times as long as wide, at base inequilaterally rounded or on proximal side shallowly cordate, the margin revolute, the straight centric midrib deeply impressed above, cariniform beneath, the 9-15 pairs of camptodrome (with random intercalary) secondary, connecting tertiary and subsequent open reticular venulation all sharply finely prominulous on both faces. Racemes loosely ±10-30-fld, the elongating axis together with peduncle (0.7-)1-3 dm; bracts firm, broadly ovate acute 4-7 mm, nidulating the very young fl-buds but cast off as soon as the pedicel elongates; pedicels ascending, at full anthesis and afterward (1.5-)2-4.2 cm; buds obliquely obovoid obtuse, fuscous- yellowish or atropurpureous; sepals firm, striate-nerved, oblong-obovate obtuse, little graduated, the longest (10-) 11-17 mm; petals yellow, when dry stramineous brown-veined, of nearly equal length but heteromorphic, the vexillar one cuneate- oblanceolate, the rest obovate, the 2 abaxial ones more obliquely and broadly so, the longest 15-23 mm; androecium glabrous, functionally 6-merous, the filaments of 4 median stamens 1.5-2 mm, of 3 abaxial ones 5-8 mm, those of the 2 latero-abaxial much dilated, the anthers of 4 median stamens oblong nearly straight 4.5-5.5 mm abruptly narrowed into a porrect 2-porose beak 0.7-1 mm, that of the central abaxial one sterile, 5.5-8 mm, prolonged at base into falcately descending lobes 1-1.5 mm, those of 2 latero-abaxial ones much the largest, lunately incurved, 14-18 mm, the theca on the abaxial side prolonged backward into a sharp tail 2-3.5 mm, that on the other much shorter, the whole anther gradually tapering at apex, minutely 2-lipped at apex; ovary subglabrous, less commonly pilosulous; style (5-)6-8 mm, slightly incurved and tapering into the oblique stigmatic cavity, near apex 0.35-0.5 mm diam. Pod stiffly obliquely descending or pendulous, the stipe 2-3 mm, the narrowly oblong piano-compressed body mostly 10-13 x 1.8-2.1 cm (shorter only due to abortion of some ovules), ±2 mm thick, the obtuse or subacute sutures little thickened, the stiff pithy valves becoming atrofuscous along the middle, paler at the edges, finely transverse-venulose, scarcely elevated over the seeds, the cavity divided into transverse chambers several times wider than long; seeds transverse, in outline narrowly oblanceolate 5.5-7 x 2-2.6 mm, the testa smooth brown sub- lustrous, ultimately crackled, the linear-elliptic areole 3.5-4 x 0.6-1 mm.—Collections: 15.
Distribution and Ecology - Scrub thickets and disturbed brush-woodland, 2600-2900 m, described as native on and near the Andean crest in centr. Ecuador and s. Colombia (Narino) but also cultivated there in parks, gardens and as a street tree, also planted and occasionally escaping into hedges and waste places in n.-e. Colombia (Cundina- marca, especially in and around Bogota, and Norte de Santander, to be expected elsewhere).—Fl. VIII-IV, perhaps intermittently through the year.
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Discussion
A coarse but handsome, truly arborescent senna, related to S. pistaciifolia sens, lat., but distinct in its reflexed and revolute, long-persistent stipules, in leaflets broadest below rather than at or above the middle, and in the relatively long filaments of the abaxial stamens. Field observations, so far as they go, suggest that S. viarum is indigenous only in Ecuador and extreme southern Colombia, but even there is locally cultivated. Northward in the eastern cordillera it is both cultivated and naturalized; the typus was collected in a village square.
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Common Names
Chalan , alcaparra de Bogota
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Distribution
Nariño Colombia South America| Cundinamarca Colombia South America| Norte de Santander Colombia South America| Ecuador South America|