Mimosa balduinii

  • Title

    Mimosa balduinii

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa balduinii Burkart

  • Description

    309. Mimosa balduinii Burkart, Darwiniana 9: 391 ("Balduini"), fig. 2 ("Balduinii"). 1951.— "Brasiliana australis, Rio Grande do Sul, Cambará, leg. Balduino Rambo S. J. No. 36.179, 6-II-1948 ’’-Holotypus, SI, not seen; isotypus, K!

    M. balduinii sensu Burkart, 1979: 239.

    Amply microphyllidious, much branched shrubs said to resemble M. bimucronata in habit, attaining 4 m with spiny trunk to 15 cm diam., armed at most nodes with a pair of ascending straight lustrous-brown, proximally subcompressed infrastipular aculei 3-9 mm, the terete, faintly striate young stems and lf-axes hispid with slender ascending rusty setae 1-2.5 mm and in addition minutely puberulent, the lvs olivaceous subconcolorous, the lfts either facially glabrous or dorsally thinly puberulent, discontinuously appressed-setose-ciliate, the short, densely flowered amentiform spikes of gray-strigulose fls single and geminate in axil of coevally expanding lvs, early immersed in foliage. Stipules herbaceous lance-attenuate to 5-6 x 1 mm, 1 -nerved, caducous. Leaf-stalks (2.5-)3-6(6.5) cm; petiole including livid pulvinus 16-28 x 0.4-0.8 mm, the interpinnal segments 6-11 mm, the ventral groove obscure, spicules 0; pinnae (2-)3-4(-5)- jug., subequilong, the rachis of distal pair 25-55 mm, the longer interfoliolar segments ± 1-2 mm; lfts of distal pinnae 16-24(-26)-jug., the first pair 0.6-1.1 mm distant from subulate herbaceous paraphyllidia 0.6-1.4 mm, the scarcely graduated blades lance-oblong or oblong-elliptic from shallowly semicordate base, abruptly apiculate, the longest ones 4—10(—11) x 1.3-3 mm, ±3-4 times as long as wide, all nerveless above, beneath 2-3-nerved from pulvinule, the midrib subcentric, simple or weakly 1-2-branched distally, the posterior nerve(s) short and weak, all immersed but discolored. Peduncles 4-12 mm, densely rusty-hispid; flower-spikes without filaments ±6 mm diam., the axis 1-3 cm; bracts slenderly lanceolate 1.2-1.7 mm, dorsally glabrous 1-nerved, setose-ciliolate, persistent; flowers sessile 4-merous 4-androus, many staminate; calyx submembranous fuscous campanulate 1-1.3 mm, glabrous externally, the rim very shortly 4-denticulate, the adaxial tooth to 0.2 mm, the rest shorter; corolla narrowly funnelform 3-3.4 mm, densely antrorse-strigulose overall, the erect, almost plane ovate 1-nerved lobes ±0.9-1.1 x 0.8 mm; filaments pink, united at base into a stemonozone ±0.3 mm, exserted 6 mm; anthers 0.7 mm diam. Pods 1-6 per spike ascending sessile, turgidly oblong-ellipsoid or ellipsoid (7-) 10-28 mm long, (l-)2-4-seeded, the stiffly papery, low-convex valves 5-6 mm wide but appearing twice as wide from a dense mantle of coarse, contiguous or even confluent, incurved-ascending setae to 5-7 mm, when ripe falling entire from hispidly setose replum; seeds (teste Burkart) ± 6 x 4 mm.

    In campo thickets at 1000-1100 m, very local on the heights of Sa. Geral near 29°S in extreme n.-e. Rio Grande do Sul (Sa. da Pedra; Cambará do Sul), Brazil, to be expected in immediately adj. Sta. Catarina.—Fl. II-V, the fruits sometimes persistent on annotinous branchlets.

    This eminently distinct temperate mimosa, instantly recognized in the context of ser. Myriophyllae by the effuse panicle of gray-silky flower-spikes subtended by coevally expanding or lately expanded leaves, worthily commemorates its discoverer, Fr. Balduino Rambo, S.J., nestor among botanists of Rio Grande do Sul.