Mimosa viva

  • Title

    Mimosa viva

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa viva Vell.

  • Description

    477. Mimosa viva Linnaeus, Sp. pl. 517. 1753.— "Habitat in Jamaicae pratis"—Holotypus, Sloane, Voy. Jamaica 2: 58, t. 182, fig. 7.1725!—Typotypus, Herb. Sloane, vol. 6, fol. 49, BM!—The specimen LINN 1228/7, acquired by Linnaeus from Patrick Browne, is not a typus. Frontispiece (L-0).

    M. viva sensu P. Browne, Civ. nat. hist. Jamaica 254. 1789; Bentham, 1841: 363; Grisebach, Fl. Brit. W.I. 218. 1864; Fawcett & Rendle, Fl. Jamaica 4: 132. 1920; León & Alain, Fl. Cuba 2: 246. 1951; Adams, Flowering pl. Jamaica 338. 1972; Bassler, 1985:608, Karte 3 (Cuba).

    Diminutive unarmed humifuse herb with very slender, randomly branched stems from a knotty subterranean caudex and rooting from infrastipular ribs at many or most nodes, commonly forming dense mats of foliage, the petioles of the highly sensitive, conjugately pinnate lvs and the solitary peduncles subvertically ascending, the stems either glabrous or thinly hispidulous with scattered setulae ±0.5-0.8 mm, the stipules and floral bracts setose-ciliolate, the subconcolorous dark green lfts all facially glabrous or the first pair of some pinnae thinly strigose dorsally, all weakly setulose-ciliolate or not so. Stipules erect submembranous, ovate or obovate 0.8-2 x 0.6- 1.2 mm, either nerveless or weakly 1-3-nerved, persistent. Leaf-stalks subfiliform (7-)10-35(-55) mm, narrowly sulcate ventrally; spicule 0; pinnae 1-jug., the rachis 5—13(—17) mm, discolored dorsally between insertion of each pair of pulvinules, the longer interfoliolar segments 0.6-1.7 mm; lfts 3-5(-6)-jug., subaccrescent upward, the first pair 0.6-1.7 mm distant from pulvinus (paraphyllidia 0), the blades oblong-obovate obtuse from obtusangulate base, the longer ones 3-5.5 x 1-2.5 mm, 2-2.7(-3) times as long as wide, all veinless above, beneath 2(-3)-nerved from pulvinule, the simple or weakly 1-2-branched midrib dividing blade 1:1.5-2, the inner (or only) posterior nerve expiring or faintly brochidodrome beyond midblade, the outer one when present short and weak. Peduncles solitary subfiliform (2-)5-2 5 mm, either shorter or longer than the subtending lf, commonly humistrate in fruit; capitula 5-9-fid, 1.5-2 mm diam. at middle, the fls and filaments all erect; bracts narrowly ovate 0.8-1.2 x 0.4-0.5 mm, dorsally glabrous 1-nerved, weakly setulose-ciliolate, persistent; flowers sessile, 4-merous 4-androus, all bisexual; calyx membranous, shallowly campanulate 0.3-0.45 mm, the deltate fimbriolate teeth 0.15-0.2 mm; corolla (1.5-)1.7-2.4 mm, subtubular, the erect ovate 1-nerved lobes 0.6-0.9 x 0.4 mm; filaments whitish, free, exserted 2.5-4 mm. Pods 1-4 per capitulum, stipitate, the stipe 2.5-3.5 mm, slightly widened upward, the 1-seeded body asymmetrically ovate in profile 3.5-4.5 x 2.5-
    3.2 mm, laterally compressed but turgidly dilated over the seed, the smooth replum ±0.2 mm wide produced into a very short curved cusp, the papery greenish, microscopically granular valves either glabrous or thinly setulose over the seed, tardily and often incompletely separating from replum; in many (but not all) pods a nodule at base of fertile article on each side giving rise to 1-2 adventitious rootlets apparently anchoring the pod to the soil; seed plumply obovoid-lenticular 2-2.6 x 1.6-1.8 mm, the testa dark brown.

    In moist pastures, on lawns, and on grassy roadsides, apparently local but probably much overlooked, known only from Cuba (La Habana e. to Oriente—cf. Bässler, l.c.) and Jamaica.—Fl. VIII-III, perhaps irregularly through the year. Map 66.

    This greatly modified mimosa is related, but not very closely, to M. skinneri, from which it differs in filiform, always radicant and unarmed stems, 1-2 (not 4-5)-nerved leaflets, extremely narrow capitula, and pods obligately 1-seeded. The adventitious rootlets that emerge from a nodule at base of the pod’s one article have no counterpart in the genus. Field observation will show whether these rootlets are contractile and serve to drag the fruit into the ground, or merely anchor it at the surface. The foliage of M. viva is said to form extensive mats in low-lying pasture and, being instantly sensitive to shock, provides a canvas for ephemeral graffiti drawn upon it with a stick or finger.