Mimosa petiolaris

  • Title

    Mimosa petiolaris

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Mimosa petiolaris Benth.

  • Description

    408.Mimosa petiolaris Bentham, J. Bot. (Hooker) 4: 376. 1841.-"Brazil, Pohl."-Holotypus, Pohl 1377 [probably a mistake for 1379], without data of origin, K (hb. Benth.)! = NY Neg. 1812; presumed isotypi, F! = F Neg. 54855, K (hb. Hook.)! NY (1209)! W (d.1379 = 1209)!—M. meticulosa var. petiolaris (Bentham) Chodat & Hassler, Bull. Herb. Boissier II, 4(6): 549. 1904, quoad nom., exclus. pl. cit. M. meticulosa var. petiolaris fma genuina Chodat & Hassler, l.c., nom. superfl.

    M. petiolaris sensu Bentham, 1875: 402 (locality surmised to be "Goyaz"), 1876: 329, t. 83, fig. 1.

    Slender, functionally herbaceous subshrubs from turbinate xylopodium, including the simple or few-branched, remotely few-capitulate efoliate inflorescence 4-11 dm tall, the lvs all subradical or the usually solitary stem bearing a petiolate lf at 1-7 nodes below middle, the stem, lf-stks and axes of pseudoraceme strigose-strigulose with forwardly appressed, either short comma-shaped or longer flagelliform setae to 0.4-2.5 mm, the vesture sometimes proximally sparse and distally denser, some basal lf-stks glabrous, the firm plane brown-olivaceous concolorous lfts glabrous facially, remotely setulose around the corneous margin. Stipules firm lanceolate 4.5-11 x 1-1.5 mm, commonly glabrous on both faces but sometimes setose dorsally, setulose-ciliate, the early ones persistent but the distal ones more easily detached in age. Leaf-stalks erect (2.5-)5-14 cm, at middle (0.4-)0.5-0.8 mm diam., rounded dorsally, shallowly sulcate or merely depressed ventrally, espiculate; pinnae 1-jug., the erect, straight or gently recurved rachis (3-)4.5-10 cm, the longer interfoliolar segments (2-)3-6 mm; lfts (10-) 12-21-jug., subvertically imbricate in sleep, decrescent at each end of rachis, the first pair 1.5-3 mm distant from pulvinus or from corneous, conic or rarely minute and subulate paraphyllidia, the anterior blade of first pair much smaller than its fellow, all blades obliquely lanceolate or dimidiately lance-ovate, obtuse apiculate, those near mid-rachis (6—)8—15 x (2.5-)3-5.5 mm, (2.2-)2.5-3.5 times as long as wide, all dorsally 5-6-nerved from pulvinule, the midrib anterior to the rest and dividing blade ±1:3-4.5, the posterior primary nerves incurved-ascending to margin, secondary venulation immersed, the single file of ciliary setae narrowly ascending, free for 0.3-1 mm. Peduncles (1.5—)2—6 cm, progressively shorter distally; capitula globose, without filaments 7-9 mm diam., prior to anthesis moriform but the glabrous lustrous yellowish-olivaceous fl-buds sometimes surpassed by bracteal cilia; bracts linear-oblanceolate 1.6-2.8 x 0.35-0.45 mm, glabrous dorsally, distally pallid-carinate and ciliate with setulae 0.5-1.4 mm; flowers 4-merous 4-androus, many lower ones staminate and shorter than the rest; calyx paleaceous 1.5-2.1 mm, cleft to below middle into deeply decompound, almost pappiform lobes; corolla funnelform 2.4-4 mm, the thickened ovate acute cymbiform lobes 0.8-1 x 0.6 mm; filaments pink, monadelphous through 1.5-2 mm, exserted 4.5-6 mm. Pods (few seen) 1-few per capitulum, sessile, in profile oblong, cuneately contracted at each end, ± 15-20 x 6 mm, piano-compressed but low-colliculate over each of 2—3 seeds, the shallowly undulate replum 0.5-0.6 mm wide, the papery valves densely strigose with forwardly appressed tapering yellowish setae to 1.5—2 mm, when ripe separating from replum and breaking up into free-falling segments ±6 mm long; seeds not seen.

    In campo sujo and campo rupestre, ±9001250 m, local, known only from basins of rios S. Bartolomeu, Ponte Alta and Descoberto in centr. and s.-w. Distrito Federal and immediately adj. Goiás, Brazil.—Fl. XII-III (-V).

    Mimosa petiolaris resembles M. pseudoradula in wandlike habit of growth and in leaves either all radical or few cauline and scattered below mid-stem, but it is a more delicate plant, instantly separable by leaflets about twice as many and hardly half as large. It is sometimes (Heringer 8366, 15367: NY host to Pilostyles.