Mimosa ursina

  • Title

    Mimosa ursina

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Mimosa ursina Mart.

  • Description

    476. Mimosa ursina Martius, Flora 21(Beibl. 11(4): 56 (=Herb. fl. bras. 136). 1838.-". . . ad Arrayal da Feira de S. Anna in mediterraneis Prov. Bahiensis."—Holotypus, Martius s.n., II—III. 1819, "inter [Feira da] Conceição et Arr. da Feira de S. Anna in desertis," M! = transparency at NY (ex K).

    M. paucisperma Britton & Rose, N. Amer. Fl. 23: 151. 1928.—"Jalisco, Chiapas, September, 1923, [C. A.] Purpus 9306"—Holotypus, US!; clastotypus, NY! — Equated with M. ursina by Grether, 1987: 320.

    M. ursina sensu Bentham, 1841: 363; 1875: 393; 1876: 310, t. 81, fig. II; Lewis, 1987, fig. 9W.

    Erect or diffusely radiating monocarpic herbs, the simple or divaricately branched stems 1-6 dm, armed at all nodes with one infrapetiolar and 1-2 infrastipular, subhorizontal, straight or gently recurved stramineous aculei 2-8(-9) mm, floriferous at indefinitely many successive lf-axils upward from below or near middle, the longer intemodes 1.5-4.5 cm, the stems, lf-stks and peduncles at once villosulous in lines with minute antrorse hairs and pilose with weak slender subhorizontal setae to 2—5 mm, the olivaceous subconcolorous, sometimes pallid-blotched lfts glabrous above, beneath coarsely subappressed- or ascending-pilose, the continuous or subcontinuous thickened margin antrorsely setose-ciliate. Stipules herbaceous lanceolate 3.5-7 x 0.7-1.4 mm, 3-5-nerved from base, glabrous dorsally, pectinately ciliate, persistent. Leaf-stalks divaricate or reflexed (when pressed), 7-21 mm; pinnae 1-jug., the incurved rachis 5-27 mm, the interfoliolar segments 2-7 mm; lfts (2-)3-5(-6)- jug., obliquely ovate from asymmetrically rounded or subcordate base, abruptly mucronate, distally accrescent and progressively asymmetrical upward, the longest 7—14(—18) x 3-8 mm, the blades weakly 3-5-nerved from pulvinule, the nerves all simple or the stronger ones tenuously 1-2-branched. Peduncles solitary (7-)9-22mm; capitula without filaments or emergent bracteal setae 2.5-4 mm diam.; bracts elliptic or narrowly oblanceolate 1-1.7 x 0.4-0.6 mm, dorsally glabrous 1-nerved, pectinately setose-ciliate, persistent; flowers 4-merous 4-androus, all usually bisexual; calyx a glabrous cup to 0.2 mm, the rim naked or charged on abaxial side with a few weak pappiform setulae; corolla narrowly vase-shaped 1.5-2.2 mm, glabrous, the firm ovate-cymbiform lobes 0.4-0.5 mm; filaments pinkish, free to base, exerted 2-4 mm. Pods ±2-12 per capitulum, sessile, in profile oblong slightly wider distally, at apex very obtuse but mucronulate, mostly 11-20 x 6-7 mm and (2-)3(- 4)-seeded, the shallowly constricted replum 0.20.4 mm wide, hispid along back and sides with erect straight tapering setae to 2-7 mm, the stiffly papery valves either densely villosulous or only microscopically papillate-puberulent overall, colliculate over each seed and there armed with 1-4 stout erect, straight or apically hooked, commonly puberulent but sometimes glabrous prickles 0.5-2.5 mm, when ripe breaking up into free- falling indehiscent articles 4-6 mm long.

    A gregariously weedy mimosa flourishing in a variety of sunny, often disturbed habitats, of bi-centric range in e. Brazil and Central America: in Brazil widespread and certainly native in cerrado, caatinga and savanna, on lateritic, rarely calcareous, often vernally inundated soils between 300 and 950 m, from the Balsas valley near 7°S in s. Maranhão e. to n. Ceará at ±4°S and centr. Pernambuco, s. through centr. and w. Bahia to 16°30'S in n.-w. Minas Gerais, thence barely entering e.-centr. Goiás; and locally abundant in grassy and sandy places, sometimes in open pineforest and occasionally on roadsides, (150-)750-l 500 m, perhaps not aboriginally native but long established in Central America, from Oaxaca to Tabasco, Mexico, s.-e. through Pacific and highland Guatemala and El Salvador to s.- w. Honduras.—Fl. in Brazil XI-IV, in Mexico and Central America (VII-)VIII-I.—A specimen of A. ursina, Glaziou 9772 (P!), cited by Glaziou (1906: 178) as collected at Araruama near Cabo Frio in Rio de Janeiro, has not been considered in the statement of range, the locality being under suspicion until confirmed. Map 67.

    Mimosa ursina is notable in its series for monocarpic duration, consistently armed nodes, conjugate pinnae incurved in the distinctive mode of ser. Modestae, small, shortly pedunculate capitula, and proportionately broad pod armed at middle of each article with a few stout erect prickles.