Mimosa

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

Description

Species Description - Functionally herbaceous from enlarged woody root, except for minutely ciliolate stipules and floral bracts glabrous throughout, eglandular, the erect, strictly few-branched, obtusely ribbed smooth purplish stems 5-8 dm tall, early defoliate below middle, finely openly foliate distally, the very small globose capitula solitary in lf-axils on subfiliform peduncles shorter than subtending lf. Stipules lance-ovate 1.5-2 mm, 1-nerved, persistent. Leafstalks subterete capillary 25-35(- 40) mm, the petiole 17-27(-30) mm, at middle 0.2-0.25 mm diam., the one interpinnal segment 6—9(—11) mm (not less than 1/3 as long as petiole); a minute or obsolescent spicule between first pair of pinnae; pinnae 2-jug., the rachis 5-11 mm, the interfoliolar segments l-2(-2.3) mm; lfts 3-5-, of most pinnae exactly 4-jug., distally accrescent but the penultimate usually largest, the first pair (2.5-)4-6 mm distant from minute paraphyllidia, all in outline obliquely elliptic or obovate-elliptic from asymmetrically rounded base, at apex depressed-deltate and apiculate, the penultimate pair 3.5-6.3 x 1.5-2.2 mm, 2-2.8 times as long as wide, all faintly 2-nerved dorsally, the midrib only a little displaced, the posterior nerve short. Peduncles 12-20 mm; capitula without filaments ±4 mm diam., prior to anthesis moriform; bracts oblanceolate 0.3-0.4 mm, subpersistent; flowers 4-merous 8-androus, not seen fully expanded, those of specimens available teratologically deformed, pedicellate, with subherbaceous perianth, and some of these giving rise to a proliferous umbelliform cluster of barren florets; expanded androecium and pod unknown.

Distribution and Ecology - In cerrado at 1000 m, 20 km w. of Montes Claros on road to Agua Bôa, Minas Gerais, Brazil, scarcely beginning to flower on 24 February 1969.

Discussion

In capillary leaf-stalks and few pairs of leaflets crowded along the distal half of the pinna-rachis this imperfectly known but almost certainly distinct species resembles M. paucifolia, but it is a taller, stiffly erect plant with shorter petioles and mostly 4 (not 2) pairs of leaflets to each pinna. Efforts should be made to collect mature healthy material.

Distribution

Brazil South America| Minas Gerais Brazil South America|