Monographs Details: Mimosa pusilliceps Barneby
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
Synonyms:Mimosa trichocephala Benth., Mimosa nycteridis Barneby
Description:Species Description - Weakly lignescent subshrubs 6(-?) dm, bushy-branching from near base, the old defoliate stems terete striate reddish-brown glabrate, the young leafy branchlets incurved-ascending, hirsute with fine erect tapering sordid setae to ± 2 mm mixed with minute puberulence and armed, but only at or shortly below some nodes, with decurved or almost straight, broad-based stramineous aculei 1-4 mm, the lf-axes and peduncles similarly but more shortly hirsutulous throughout, unarmed, the olivaceous foliage bicolored, the plane thin-textured lfts glabrous above or on both faces (only a few proximal ones thinly strigose beneath), all remotely or discontinuously ciliate with fine ascending setae, the minute capitula globose, either solitary, or geminate, or paired with a very slender branchlet, in a long succession of lf-axils. Stipules incurved to erect, linear-attenuate 2-2.5 x 0.2-0.3 mm, 1-nerved, glabrous dorsally, setose-ciliate, becoming dry but mostly persistent. Leaf-stalks including discolored pulvinus 13-23 mm, at middle 0.2-0.3 mm diam., narrowly 2-ribbed ventrally, espiculate; pinnae 1-jug., the rachis of each 15-25 mm, the interfoliolar segments 2-2.7 mm; lfts 9-12-jug., abruptly decrescent at base of rachis, less so distally, the first, often very unequal pair 0.7-1 mm distant from subulate paraphyllidia 0.2-0.5 mm, all in outline narrowly oblong or obscurely oblong-oblanceolate from obtusangulate base, abruptly apiculate, those near mid-rachis 9-12 x 2-3 mm, 3.6-4.5 times as long as wide, all veinless above, slenderly impressed-venulose beneath, the subcentric midrib tenuously pinnate-branched, the primary nerves on either side of it expiring well beyond mid-blade, the 1-2 outer posterior nerves very short. Peduncles subcapillary 15-28 mm; capitula without filaments 2-2.5 mm diam., prior to anthesis moriform but thinly hispidulous with emergent bracteal setae; bracts oblanceolate incurved 0.65-1.1 x 0.25-0.3 mm, weakly carinate, glabrous dorsally, charged on each side beyond middle with 3-4 ascending cilia; flowers 4-merous 4-androus, mostly bisexual; calyx-tube membranous ±0.2 mm, the rim with a few capillary setulae 0.3-0.45 mm; corollas narrowly turbinate 1.5-2.7 mm, glabrous, the ovate, dorsally keeled, shallowly concave lobes 0.7-0.8 x 0.4-0.5 mm; filaments pink, very shortly monadelphous around base of glabrous ovary, exserted 2.5 mm; pod unknown.

Distribution and Ecology - About seeps on rock outcrops between 350 and 620 m, known only from the e. slope of Sa. dos Gradaús, near 8°S in s.-e. Pará, Brazil.—Fl. II- III(-?). Map 56.

Discussion:

This is in most respects similar to M. trichocephala, but clearly distinct in the minute, relatively long-pedunculate capitula and short filaments.

Distribution:Brazil South America| ParĂ¡ Brazil South America|