Monographs Details: Mimosa congestifolia Burkart
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
Description:Species Description - Slender unarmed microphyllidious shrubs 1-2 m, the defoliate trunks scabrous with persistent stipules or their tattered remnants, stiffly few-branched distally, the homotinous branchlets strictly ascending, densely clothed in ascending sessile lvs, the internodes mostly less than 5 mm, the young stems and dorsal face of pinna-rachises densely strigose with forwardly subappressed, tapering or flagelliform, smooth setae 1-4 mm, the foliage olivaceous concolorous, the lfts facially glabrous, remotely setose-ciliolate, the ovoid-ellipsoid capitula solitary in distal lf-axils on peduncle shorter than subtending lf. Stipules erect, broadly lanceolate 2.5-7 x 1-1.7 mm, the chartaceous castaneous blade dorsally glabrous and striately 10-17-nerved, persistent. Leaf-stalks 0, the one pair of pinnae arising directly from lf- pulvinus, the rachis 3-5.5 cm, the interfoliolar segments 1-1.6 mm; lfts (21-)24-40(-43)-jug., subequilong except at very ends of rachis, the first pair less than 1 mm distant from paraphyllidia 0.4-1.4 mm, the blades linear or linear-oblanceolate from narrowly semicordate base, obtuse at apex, the longer ones 4.5-9 x 0.9-1.4 mm, 4.6-7 times as long as wide, all veinless above, 3-nerved beneath, the simple subcentric midrib flanked on either side by a weak primary nerve produced almost to blade apex. Penduncles 1.5-3.5 cm; capitula without filaments 5.5-8 mm diam., prior to anthesis conelike; bracts resembling stipules in texture and coloration, linear-elliptic 2.5-3.5 x 0.4-0.5 mm, glabrous and finely 3-5-nerved dorsally, pectinately ciliate, persistent; flowers 4-merous 4-androus, some lower ones staminate; calyx membranous campanulate 0.7-0.9 mm, the shortly, sometimes asymmetrically toothed rim minutely ciliolate; corolla subcylindric 3-3.8 mm, the tube glabrous, the cymbiform lobes 1-1.2 x 0.6-0.7 mm, puberulent on either side of prominulous midrib, not thickened at tip; filaments pink, free to base or almost so, exserted 6.5-7.5 mm. Pods several from middle and top of receptacle, sessile, in profile narrowly oblong 12-25 x ±6 mm, 2-4- seeded, the almost straight replum ±0.5 mm wide, contracted apically into an erect cusp ±2 mm, armed with pluriseriate straight divaricate lustrous setae to 3-3.5 mm, the papery brown valves colliculate over each seed, thinly shortly ascending-setulose, when ripe breaking up into free-falling articles ±6 mm long; seeds not seen.

Distribution and Ecology - Highly localized in cloud-forest of Sa. do Mar at 1200-1700 m in e. Paraná, Brazil, between 25°15' and 25°30'S (mun. Campina Grande do Sul, Cuatro Barras, Morretes).—Fl. I—III.

Discussion:

Burkart referred M. congestifolia to ser. Pedunculosae, but could find no particular relative in that series. The species is in fact much closer to habitally similar M. microcarpa and M. itatiaiensis of central and southern Minas Gerais, the first of which was aligned by Bentham with his ser. Meticulosae. It has much in common also with M. bocainae and M. reduviosa, newly described species narrowly endemic to eastern S. Paulo and northeastern ParanĂ¡ respectively, which are technically distinguished by reversed setose indumentum of the stems. In the context of this series of vicariant microspecies M. congestifolia may be recognized by the combination of relatively long pinnae and leaflets, broad striately nerved stipules, and ellipsoid capitula conelike prior to anthesis.

Distribution:Brazil South America| ParanĂ¡ Brazil South America|