Mimosa glabra Benth.

Authors

Rupert C. Barneby

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.

Family

Mimosaceae

Scientific Name

Mimosa glabra Benth.

Type

368. Mimosa glabra Bentham, J. Bot. (Hooker) 4: 386. 1941.-"Brazil, Sello."-Holotypus, Sello d. 1480, collected (Malme, 1931:13) near Rio Pardo in Rio Grande do Sul, K (hb. Benth. & hb. Hook., mounted together)!; isotypi, +B = F Neg. 1325, G! P (hb. Gaudi

Description

Species Description - Shrubs of unknown stature, except for 1-2 short ascending setae at insertion of each 1ft and (in few distal lvs) random minute setulae at margin of some lfts glabrous throughout, the stiff virgate, chocolate-brown stems terete striate and armed with stout straight ascending stramineous aculei 4-8 mm, these (1 —)2—3 per intemode on either infrastipular or infrapetiolar ribs but always well below the node itself, the dry foliage dull dark brown concolorous, the globose capitula solitary in upper lf-axils, the fruits long-persistent on annotinous defoliate stems. Stipules firm erect, lanceolate 2—4 x 0.7-1 mm, 3-nerved, persistent. Leaf-stalks (5-)7-14 x 0.3-0.4 mm, shallowly sulcate, espiculate; pinnae 1-jug., the rachis (6-) 12-20 mm, the interfoliolar segments 1.2-2.5 mm; lfts 6-9(-10)-jug., the first and last pair smaller, the blades in outline oblong from obtusangulate base, obtuse or deltately acute, the larger ones 6-8.5 x 2-2.5 mm, all narrowly continuously marginate, dorsally 3-nerved, the simple midrib dividing blade ±1:2, the inner posterior nerve expiring just short of apex, the outer one much shorter. Peduncles 13-30 mm; capitula without filaments 6-7 mm diam., prior to anthesis moriform, the 4-ribbed obtuse fl-buds minutely puberulent; bracts 1-1.5 x 0.4-0.6 mm, keeled dorsally, minutely puberulent, deciduous; flowers 4-merous 4-androus, all (?) bisexual; calyx campanulate ±0.2 mm, glabrous; corolla narrowly vase-shaped 3-3.3 mm, the ovate concave lobes 0.9 x 0.8-1 mm, a little thickened at apex, puberulent near margins, the tube thinly puberulent with minute retrorse hairs; filaments presumably pink, free to base, exserted 6-7 mm. Pods mostly 1-2 per capitulum, sessile, when fully fertile narrowly oblong-ellipsoid turgid, only a little compressed laterally, 12-24 x 4-5 mm, 2-5-seeded, the replum ±2 mm wide, the leathery brown valves smooth veinless, tardily separating in one piece from replum, the cavity divided between seeds by hyaline septa; seeds basipetal, plumply obovoid-ellipsoid ±4x2 mm, the testa dark brown smooth.

Distribution and Ecology - In unknown habitat but to be expected in campo thickets, recorded only from the type-locality near Rio Pardo, in the Jacuí valley near 30°S in e.-centr. Rio Grande do Sul, Brazil.—Fl. season unknown.

Discussion

The pod of M. glabra resembles, on a small scale, that of several members of sect. Habbasia ser. Pachycarpae, but is smooth and glabrous. So far as known all other Sparsae bear conventional craspedia, and valvately dehiscent fruits are known from extratropical Brazil only in sect. Batocaulon ser. Stipellares and sect. Calothamnos. Mimosa glabra is consequently isolated in the genus and here associated with ser. Sparsae on the basis of vegetative and floral resemblances.

Distribution

Brazil South America| Rio Grande do Sul Brazil South America|