Mimosa melanocarpa 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
222. Mimosa melanocarpa Bentham, Trans. Linn. Soc. London 30:437. 1875 & in Martius, Fl. bras. 15(2): 381, char. ampliat. 1876.— "Habitat in provincia S. Paulo: Burchell n. 5452; ad Villa de Batataës ejusdem prov.: Regnell coll. III, n. 510; inter Franca
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Synonyms
Mimosa adenotricha Benth.
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Description
Species Description - Closely resembling M. setosa subsp. setosa in habit, in triple pubescence (the cauline plain setae sometimes suppressed) and in exserted leafless inflorescence, in stature attaining 1-3 m, different in lfts on average more numerous and more crowded, in externally setulose calyx, and some features of the pod. Stipules of M. setosa, but the blades sometimes puberulent internally. Leafstalks of larger lvs 9-25 cm, the interpinnal segments 8—16(—19) mm; spicules of M. setosa; pinnae 9-16-jug., the rachis of longer ones 3-7.5 (-8.5) cm, the longer interfoliolar segments 0.8-1.4 mm; lfts of longer pinnae (36-)40-60(-65)- jug., narrowly oblong obtuse, the longer ones 3.5-6.5(-7) x 0.7-1.5 mm, faintly l(-2)-nerved dorsally. Inflorescence simply pseudoracemose or paniculate, well exserted from foliage, the capitula like those of M. setosa; bracts spatulate acute 3-5.5 x 0.7-1 mm, densely setose and stipitate- glandular dorsally; flowers: the calyx including dense external setose pubescence (1.5-) 1.7-3 mm, the tube ±0.5 mm, concealed by vesture; corolla 4-5.2 mm, the narrowly funnelform tube glabrous or distally puberulent, the lobes 1-1.7 mm, finely setulose dorsally; filaments pink, monadelphous through 0.9-1.4 mm, those of bisexual fls exserted 7.5-9 mm. Pods when well fertilized (4.5-)5-8 cm x 6-7.5 mm, (4-)5-8-seeded, long-attenuate both at base and apex, the stipe or sterile base of body and stipe together 6-16 mm, the tapering beak 9-15 mm, the undulately constricted replum 0.5-0.9 mm wide, the livid exocarp and pallid endocarp of valves together ±0.15 mm thick in section, the replum and valves alike villosulous, glandular-setulose and remotely setose, the ripe valves breaking up into free-falling, individually dehiscent articles longer than wide, those at mid-pod 6-11 mm long; seeds subvertically basipetal, broadly ovate-suborbicular in broad outline, ±4.3 x 3.4 mm, the testa smooth lustrous.
Distribution and Ecology - In cerrado and becoming weedy in disturbed ground and on waysides, ±650-1000 m, discontinuously widespread from Sa. do Roncador in e. Mato Grosso e. to s. Espigão Mestre in s.-w. Bahia, s. through centr. and s. Goiás and Distrito Federal to 19°S in the Triângulo of Minas Gerais, endemic to the Brazilian Planalto.—Fl. V-VIII. Map 30.
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Discussion
Mimosa melanocarpa closely resembles M. setosa, from which it is most easily and reliably distinguished by the externally setose calyx. The leaflets are mostly smaller and more crowded, and the pod more pronouncedly stipitate, breaking up into proportionately longer articles. All flowering collections of M. melanocarpa known to me were made in the dry autumn and early winter months of May to July, whereas almost all collections of flowering M. setosa are dated between late September and March. This asynchrony in flowering may preserve the identity of the species where they are sympatric.
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Distribution
Brazil South America| Minas Gerais Brazil South America| Bahia Brazil South America| Goiás Brazil South America| Distrito Federal Brazil South America|