Mimosa brachycarpa Benth.
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1991. Sensitivae Censitae. A description of the genus Mimosa Linnaeus (Mimosaceae) in the New World. Mem. New York Bot. Gard. 65: 1-835.
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Family
Mimosaceae
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Scientific Name
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Type
284. Mimosa brachycarpa Bentham, J. Bot. (Hooker) 4: 410. 1842.-"Serra da Lapa [in Sa. do Espinhaço n. of Belo Horizonte, centr. Minas Gerais, Riedel, misit] LangsdorfF."- Holotypus, Riedel 17 =715, collected XI. 1824 (fl, fr), LE! = NY Neg. 11675; isotyp
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Description
Species Description - Erect, usually unarmed but at times randomly or remotely aculeate, stiffly branched shrubs 1-2 m, the young stems, lf-axes and pods densely strigose or hispid with basally thickened, either short subappressed or longer flagelliform-attenuate (then shaggy) setae to 0.5-2.5 mm, the old trunks to 5-6 mm diam., the simple virgate hornotinous ones clothed in narrowly ascending, distally diminished lvs, the shortly pedunculate subglobose capitula at first axillary and immersed in foliage, but later forming an exserted pseudoraceme. Stipules broadly lanceolate or ovate, acute or acuminate 3-6 x 1.5-2.5 mm, the dry brown, closely striate-venulose blade glabrous on both faces, ciliate. Leaves subsessile, heteromorphic: a) primary cauline with 5-10 pairs, and b) shorter distal ones with 2-5 pairs of pinnae; lf-stks stout stiff 1-5.5 cm, the longer interpinnal segments 2.5-6 mm; between each pair of pinnae a papery triangular-ovate-acuminate scale (dilated spicule) 1-1.8 mm resembling a diminished stipule; rachis of longer pinnae 1-2 cm, the interfoliolar segments to 0.3-0.8 mm; paraphyllidia 0; lfts 18-30-jug., the small proximal ones next to pulvinus, the blades in sleep subvertically imbricate, in outline linear obtuse, the longer ones 2.5-4.5 x 0.4-0.7 mm, all when dry brownish and veinless above, beneath olivaceous, the finely prominulous centric midrib weakly ±2-branched on each side. Peduncles often solitary, sometimes 2-3 per node, 3-20 mm; capitula squatly ovoid or globose, prior to anthesis conelike, without filaments 5-7 mm diam.; bracts resembling stipules in texture and striate venulation, ovate or lanceolate from cuneate base, those near mid-capitulum 2-3 x 0.6-1.4 mm, all glabrous dorsally ciliolate; flowers 4-merous 8-androus, a few of the lowest often smaller and staminate; calyx campanulate 0.35-0.6 mm, its truncate or shallowly denticulate rim ciliolate; corolla glabrous turbinate 2-2.6 mm, the almost plane ovate lobes 0.7-1.2 mm, striately 9-11-nerved; filaments pink, free, exserted 5-7 mm. Pods several per capitulum, ascending in a subumbellate cluster, sessile or almost so, in profile oblong-elliptic abruptly mucronate 12-18 x 4-6 mm, (2-)3-5-seeded, the replum ±0.5 or rarely to 1 mm wide, the papery, densely setose valves colliculate over each seed, when ripe deciduous in one piece from the long- persistent replum; seeds ±3.5-3.8 x 2.4 mm, the testa lustrous dark brown.
Distribution and Ecology - In cerrado, at edge of gallery woodland and in wet campo, sometimes becoming colonial on road-cuts, 350-950 m, discontinuously dispersed in two phytogeographically distinct sectors of the Brazilian Planalto: valleys of rios Araguaia and Tocantins s.-ward from 7°S in Goiás and adj. Mato Grosso, e. to sources of rio Parnaíba in far s. Piauí; and on Sa. do Espinhaço between 16°30' and 19°30'S in Minas Gerais. — Fl. X-VIII, perhaps intermittently through the year. Map 42.
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Discussion
At anthesis M. brachycarpa closely resembles the bracteose varieties of M. somnians, but may be distinguished by dissection of the ovary, which contains not more than six ovules (vs. 7-15 for M. somnians). In fruit the striate corolla marcescent at base of the short subsessile pod, the valves of which fall away from the replum without articulation, is an unmistakable combination. The low ovule-number is compensated by the number of pods that reach maturity, these usually forming an umbelliform head reminiscent of M. camporum.
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Distribution
Brazil South America| Minas Gerais Brazil South America| Goiás Brazil South America| Piauí Brazil South America| Mato Grosso Brazil South America|