Mimosa plumosa

  • Title

    Mimosa plumosa

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa plumosa Micheli

  • Description

    219. Mimosa plumosa M. Micheli, Mem. Soc. Phys. Geneve 30(7): 91, t. 26. 1889.—"[Paraguay] In valle Y-acan prope Valenzuela. [5] Mart. [1883, Balansa] n. 4424.— Holotypus, G!; isotypi, C! F! P!

    M. plumosa sensu Chodat & Hassler, 1904: 554; Burkart, 1964: 358.

    Stout unarmed, coarsely leafy subarborescent shrubs attaining 3 m, with finely ribbed homotinous branches 3-9 mm diam., these with all lf-axes and peduncles hispid-tomentulose with mixed longer and shorter erect, arborescently branched setae, the longer ones 2-5 mm and simple distally, the shorter ones branched or scaberulous to apex, the subconcolorous brownish-olivaceous lfts pannose-tomentose on both faces with shorter-stalked interlocking substelliform setulae, the stout oblong-ellipsoid capitula 1-4 together from the axil of coevally expanding lvs and early surpassed by them, the fruits immersed in foliage. Stipules erect, narrowly lanceolate 9-18 x 1-2 mm, pubescent dorsally like stem, becoming dry fragile but persistent. Leaf-stalks 15-30 x 1.2-1.6 mm, pinnae 1-jug., the rachis (5-)6-10.5 cm, the interfoliolar segments 5-10 mm; lfts 9-13-jug., subequilong except near base of rachis, the small unequal first pair 1.5-3 mm distant from subulate paraphyllidia 1-2.5 mm, the blades oblong-elliptic from deeply semicordate base, deltately acute and mucronulate at apex, those at and beyond mid-rachis 17-36 x 5.5-11 mm, 2.7-3.7 times as long as wide, all ventrally veinless or almost so, dorsally beneath the stellate vesture prominulously 3-nerved from pulvinule, the midrib displaced to divide the blade ± 1:2, the incurved-ascending inner posterior nerve expiring beyond mid-blade, the outer one much shorter. Peduncles (1.5—)2—5 cm; capitula without filaments ± 15-30 x (9-) 10-13 mm, prior to anthesis conelike hispid; bracts linear or subfiliform 3-5 x 0.2-0.25 mm, dorsally from base upward finely setulose and substellate, the remotely branched setae to 1.2-2 mm, intermixed with minute gland-tipped setulae; flowers 4-merous 4-androus, all bisexual; calyx reduced to a glabrous or minutely ciliolate, obscurely crenulate collar 0.2-0.3 mm tall, the rim either glabrous or minutely ciliolate; corolla submembranous, narrowly funnelform and often a little curved at base, 3—4 mm, the tube thinly puberulent with simple hairs, the ovate, delicately 1-nerved lobes ±1.5-1.7 x 0.8-1 mm, more densely pubescent with small branched hairs; filaments pink, free to base, exserted 4.5-7mm; ovary densely lanulose overall or only dorsally. Pods many in ovoid but not incompressible clusters, sessile, in profile narrowly oblong, obtuse at both ends but apiculate at apex, (2-)3-4-seeded, when well fertilized 15-32 x 6-8 mm, the replum ±0.5-0.7 mm diam., together with the papery valves hispid and stellate-tomentulose with fine pliant yellowish, basally plumulose but distally glabrous setae 2-3 mm intermixed with short stelliform setulae and minute orange-tipped glandular ones, the ripe valves breaking into free-falling, individually dehiscent articles 5-8 mm long, the cavity continuous (no interseminal septa); seeds ±5-6 x 3-3.5 mm, compressed-obovoid-ellipsoid, the testa livid dull.

    In thickets at edge of wet campo at ±200-250 m, localized on the w. extension of the Paraguayan Plateau near 20°30'S, 57°W in w.-centr. Paraguay (depto. Cordillera, near Tobatí and Valenzuela).—Fl. XII-III(-?).

    This is a very distinct species, distinguished by coarse unijugate leaves, oblong-ellipsoid capitula of pink flowers, these pilosulous with mostly simple (the corolla-lobes with some branched) hairs, filaments free to base, and small gland-tipped setulae intermixed with longer, basally plumulose and shorter, substelliform setae of floral bracts and pods.