Mimosa verecunda Benth.

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

Scientific Name

Mimosa verecunda Benth.

Type

383. Mimosa verecunda Bentham, J. Bot. (Hooker) 4: 368. 1841.-"Brazil, Pohl", the locality precised in Martius, Fl. bras. 15(2): 318. 1876: "in provincia Goyaz ad Santa Rita [near 15°30'S in w.-centr. Goiás]."-Holotypus, Pohl [1922] = d.1475, K (hb. Benth

Synonyms

Mimosa polycarpa Kunth

Description

Species Description - Virgately erect or pliantly arching, micro-phyllidious shrubs and subshrubs 1-3 m, commonly armed at or shortly below each node with a pair of recurved broad-based stramineous aculei 1—4 mm and sometimes in addition with a few scattered intemodal or distantly infrastipular ones, occasionally unarmed, the homotinous stems, lf-stks and axes of inflorescence strigose or rarely hirsute with forwardly appressed or exceptionally spreading-ascending, tapering or flagelliform, whitish or refuscent setae to 1-3 mm, mixed or not with minute puberulence, the foliage olivaceous, the narrow crowded thin-textured lfts ± bicolor, green and either glabrous or finely minutely puberulent above, beneath paler, commonly purple-tipped, subappressed-silky-setose, the margins finely setose-ciliate, the numerous small, plumply ovoid capitula mostly verticillate by 2-7 in upper lf-axils and beyond, forming a simple dense, basally foliate and either distally efoliate or hysteranthously leafy pseudoraceme 1.5-5 (-7) dm long. Stipules firm erect, lanceolate or linear-attenuate 3.5-8 x 0.5-1.4 mm, coarsely 3-nerved, dorsally either setulose and puberulent or glabrous, setose-ciliate, persistent. Leaf-stalks (sensitive, in most specimens deflexed) subterete, those of most lvs 2—9(—11) cm (of small bracteiform uppermost lvs shorter, no further described), the petiole 1.5-6(-7) cm, at middle (0.4-)0.5-0.9 mm diam., the interpinnal segments (1—)2—11 (— 14) mm, spicules 0; pinnae of longer lvs 2-5 (of random distal lvs only l)-jug, either the proximal or the distal ones longest, the rachis of longer ones (3.5-)4-8.5 cm, the interfoliolar segments 1-2.1 mm; lfts of longer pinnae 38-55(-60)-jug., decrescent toward each end of rachis, the first pair less than 1 mm distant from subulate-setiform paraphyllidia 0.8-2.2 mm, all in outline linear or linear-lanceolate, acute and mucronate, from semicordate base, those near mid-rachis 4.5-8.5 x (0.5-)0.6-1.3 mm, (5.8-)6-9 times as long as wide, all smooth above, dorsally 1-nerved by simple subcentric costa, this commonly immersed proximally but prominulous and pallid near blade apex. Peduncles 6-21 mm; capitula without filaments 4.5-5.5 mm diam., prior to anthesis moriform but hispidulous with emergent bracteal setae; bracts oblanceolate incurved 1.2-1.8 x 0.3-0.5 mm, dorsally glabrous and carinate by midrib, setose-ciliolate distally; flowers 4-merous 4-androus, a few proximal ones sometimes staminate but mostly bisexual; calyx paleaceous-pappiform, the membranous tube 0.2-0.4 mm, externally glabrous, entire or irregularly cleft, the rim ciliate with subcapillary, sometimes obscurely confluent setae to 0.6-1.1 mm; corolla membranous subcylindric 1.8-2.7 mm, the cymbiform, weakly carinate and scarcely thickened lobes 0.55-0.8 x 0.4-0.5 mm, hispidulous distally; filaments lilac-pink, weakly monadelphous through 0.2-0.5 mm, exserted 4-6 mm; ovary minutely stipitate glabrous. Pods usually numerous in each capitulum and forming a radiating cluster, subsessile, in outline narrowly oblong 13-19 x 4-5 mm, abruptly contracted into an apical cusp 2-3 mm, the shallowly constricted replum 0.4-0.6 mm wide, hispid with three or more files of divaricate setae of different lengths (the longer to 2.5-5 mm), the papery green or brownish valves glabrous to thinly retrostrigulose or at once setulose and densely puberulent, when ripe breaking up into free-falling biconvex articles 4-5 mm long; ripe seeds not seen.

Distribution and Ecology - Along margin of gallery forest and in adjoining cerrado, 850-1050 m, locally common between 13°30' and 18°30'S in centr. and s.-e. Goiás and in the enclave of Distrito Federal, Brazil.—Fl. (I-)II-VI.

Discussion

Because of the two to five pairs of pinnae in each major cauline leaf, M. verecunda was aligned by Bentham (1875: 397) in ser. Pudicae next following M. polydactyla, but its really close kinship, if this can be inferred from similarity in leaflets, inflorescence, calyx, and craspedium, is with conjugately pinnate M. xanthocentra. Like the latter, M. verecunda occurs in armed and (less common) unarmed states, and is similarly variable in indumentum, the type specimens, for example, having hispid stems but most modem examples strigose ones. In its upland planaltine range of dispersal M. verecunda differs in number of pinnae from all sympatric eu-mimosas other than Mm. pudica, hirsutissima, rufipila, macrocephala, procurrens, and plurijugate forms of M. distans; but it exceeds all these in number of leaflets (38-90 pairs in longer pinnae), and differs further either in narrower leaflets, or in structure of the calyx, or in both at once.

Distribution

Brazil South America| Distrito Federal Brazil South America| Goiás Brazil South America|