Mimosa nitens

  • Title

    Mimosa nitens

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa nitens Benth.

  • Description

    232. Mimosa nitens Bentham, J. Bot. (Hooker) 4: 404. 1842.—"Brazil, Pohl", the locality expanded in Martius, Fl. bras. 15(2): 385. 1846 to: "in provincia Goyazensi ... ad rio Trahiras."—Holotypus, Pohl d.1464 = 1737, K (hb. Benth.)! = NY Neg. 1905; isotypi, F! = F Neg. 54850, NY! W (labelled "Crixas, Trahiras")!

    M. nitens sensu Bentham, 1876: 439.

    Amply leafy unarmed shrubs or subshrubs 1.5-2m, the stout lustrous homotinous stems hispid with erect or incurved-ascending tapering setae to 2-7 mm and rarely also minutely villosulous, the lf-stks and axes of inflorescence more shortly setose, the foliage subconcolorous, the plane, when dry brown lustrous lfts glabrous on both faces, marginally thinly villosulous or setulose-ciliolate, the inflorescence a few-branched panicle of pseudoracemes elevated ±2-4 dm beyond contemporaneous leaves. Stipules firm lanceolate or ovate 3-6 x 1-2.5 mm, either glabrous or setulose dorsally, early dry deciduous. Leafstalks (1.5—)2—9 cm, dorsally rounded, openly shallow-sulcate ventrally, the petiole including livid wrinkled pulvinus 5-22 x 1.5-2 mm, the longer interpinnal segments (3—)5—16 mm, the ventral sulcus bridged between pinna-pairs but spicules 0; pinnae (2-)3-7(-8)-jug., accrescent distally, the rachis of longer ones 6-11 cm, the first pair of lfts 1-2 mm distant from subulate (at times obscure or obsolescent) paraphyllidia, the longer interfoliolar segments 1.5-2.5 mm; lfts of longer pinnae 3 5-5-jug., in outline narrowly lance-oblong obtuse from dilated auriculate base, straight or slightly arched forward, the larger ones 8-14 x 1.5-3.5(-4) mm, all weakly 5-7-nerved from pulvinule, the subcentric midrib and adjacent primary nerve on each side of it produced nearly to blade apex, the posterior ones much shorter. Peduncles 1.5-3(-4.5) cm; capitula without filaments 9-10 mm diam., prior to anthesis conelike; bracts narrowly or broadly rhombic-oblanceolate 2.5-5 x 0.5-1.5 mm, always setose-ciliate but dorsally either setulose or glabrate, either equalling or surpassing the fl-buds; flowers 4-merous 8-androus, the lower ones staminate and slightly shorter than the distal bisexual ones; calyx 0.5-0.85 mm, setulose externally, the orifice ciliate with setae to 0.8-1.4 mm; corolla narrowly funnelform 4-5 mm, the tube glabrous, the ovate distally subcallous and dorsally setulose lobes 1.1-1.5 mm; filaments pink, monadelphous through ±0.7-1 mm around stipe of pilosulous ovary, exserted 7-13 mm. Pods 1-3 per capitulum, ascending, subsessile or contracted into a stipe to 3 mm, in profile oblong-elliptic 30-45 x 8-14 mm, abruptly contracted at apex into a stout subulate cusp ±3 mm, the replum 1-1.5 mm wide, the low-convex stiffly papery, externally nigrescent and thinly setulose, internally rufescent valves separating entire from replum, the cavity (5-)6-9 seeded; seeds not seen.

    In cerrado, 700-800 m, apparently local on upper forks of rio Tocantins in lat. 12°30 -14°30'S in centr. Goiás (Arraias, Trahiras, Niquelândia), Brazil.-Fl. I-III.

    Mimosa nitens has the efoliate paniculate inflorescence of M. setosa sensu lato or M. melanocarpa, but differs at anthesis by relatively few pairs of pinnae, and in fruit by valvate dehiscence of the pod. As often happens in Mimosa, a reduced number of pinnae is compensated by greater length, the whole leaf-formula being characteristic in high degree. The type-collection has simply setose, otherwise hairless stems, but one modem collection (Irwin 34991, NY) includes both exactly typical individuals and others with stems at once more shortly hispid and villosulous.