Mimosa itatiaiensis

  • Title

    Mimosa itatiaiensis

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa itatiaiensis Dusén

  • Description

    448. Mimosa itatiaiensis Dusen, Arq. Mus. Nac. Rio de Janeiro 13: 56. 1903.—"In parte septentrionali territorii [montis Sa. da Itatiaia], . . . verisimiliter in alt. ca. 2500 m.s.m. ab E. Ule inventa."—Holotypus, Ule 610, Rio Preto, 31.XII. 1895, R!; isotypus (fragm), S!; presumed isotypus, "rio Preto, Itatiaia," Ule 3709, K!

    M. microcarpa sensu Glaziou, 1906: 179, ex parte, quoad 8652 (C! G! P! K!), 15926 (C! P! K!).

    Stiffly virgate, unarmed microphyllidious shrubs or subshrubs 5 dm upward, with livid defoliate trunk strictly few-branched distally, the homotinous branchlets clad in narrow, subvertically imbricate sessile lvs, hispidulous or in youth silky-setose with ascending brownish flagelliform setae 1-2.5 mm (the flagellum deciduous in age), the thick-textured, ventrally concave lfts glabrous eciliate, the globose or plumply ellipsoid capitula shortly pedunculate in the axil of distal, coevally expanding lvs. Stipules firm erect lance-acuminate 3-6 x 0.5-1 mm, 3-5- nerved, setulose dorsally and ciliate, persistent. Leafstalks reduced or almost so to hard setulose pulvinus, 1.5-2 mm; pinnae 1-jug., the rachis 1.2-3.5 cm, the longer interfoliolar segments 0.61 (—1.4) mm; lfts of longer pinnae (15-) 18-25- jug., decrescent toward each end of rachis, the first pair less than 1 mm distant from setiform paraphyllidia concealed by setulae, the blades linear or lance-elliptic from semicordate-auriculate base, obtuse at apex, those near mid-rachis 4-7 x 0.9-1.6 mm, 4-5.3 times as long as wide, all veinless above, beneath slenderly 2-4-nerved from pulvinule, the scarcely excentric midrib simple or once forked below middle, the inner posterior nerve produced nearly to blade apex, the rest weak and short. Peduncles 1-4 cm; capitula without filaments ±6—7.5 mm diam.; bracts linear or narrowly oblanceolate 2-3.5 x 0.2-0.4 mm, 1-nerved; flowers 4-merous 4-androus; calyx membranous campanulate 0.4-0.5 mm, asymmetrically denticulate, the rim either naked or with few random setulae; corolla narrowly funnelform 2.5-2.8 mm, the cymbiform but scarcely thickened, dorsally 1-ribbed lobes ±0.8 x 0.5 mm, antrorsely gray-puberulent externally; filaments free, exserted ±6 mm. Pods ±2-5 per capitulum, sessile, in profile elliptic or oblong 8-12 x 4.5-6 mm, 2-3 seeded, the replum nearly 1 mm wide, contracted into an apical cusp 1-1.5 mm, the replum and papery valves alike hispid with ascending tapered setae 1-1.5 mm, the ripe valves separating in one piece from replum, the interseminal septa subobsolete; seeds not seen.

    In brushy campo at high elevations near crest of Sa. da Mantiqueira on the Minas Gerais-Rio de Janeiro boundary (Ayuruoca; Sa. da Ita- tiaia).—Fl. XI-XII(-?).Mimosa itatiaiensis is closely related to M. microcarpa, found in similar environment on heights of Sa. do Espinhaço in central Minas Gerais, but differs in venation of stipules, floral bracts, and corolla-lobes, as recorded in the foregoing key. The lower bracts in M. microcarpa are striately 5-9-nerved and form a pseudo-involucre under the capitulum, whereas those of M. itatiaiensis are 1- or exceptionally 3-nerved and each subtends a flower. No isotype was found in 1984 among Ule’s collection at Hamburg.