Mimosa casta

  • Title

    Mimosa casta

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Mimosa casta L.

  • Description

    319. Mimosa casta Linnaeus, Sp. pl. 518.1753.— "Habitat in India."—Lectotypus, proposed by Wijnands, The Botany of the Commelins 151. 1983: Herb. cliffort. 208.2, a sterile cultivated specimen, BM!

    M. dominiciana Desvaux, Ann. Sci. Nat. Bot. 1,9: 424. 1826. — "Hab. in Dominica."—Holotypus, communicated by Wm. Hamilton, not seen, but the protologue and locality decisive.—Equated with M. casta by Bentham, 1846: 85.

    M. casta sensu Bentham, 1841: 364, 1875: 310, 1876: 393; Britton & Rose, 1928: 151; Britton & Killip, 1936: 150; Croat, Fl. Barro Colorado Is. fig. 268. 1978; Cardenas, Acta Bot. Venez. 14(4): 95. 1985 [1987].

    Prickly scrambling vines 2-4 m, procumbent when unsupported, armed on the obtuse cauline ribs and along the dorsal and lateral ribs of lf-stks with files of recurved, broad-based, stramineous-tipped aculei 1-3.5 mm, otherwise either glabrous throughout, or the pinna-rachises and rarely the whole lf finely minutely puberulent, the ample thin-textured lfts bicolored, dark green or (dry) brown above, paler beneath, sometimes thinly appressed-setose dorsally, finely subcontinuously ciliate with forwardly appressed setae, the small globose, shortly pedunculate capitula solitary or 2-3 together in lf-axils, sometimes in praefloration forming a shortly exserted pseudoraceme but this hysteranthously foliate. Stipules firm erect, lance-acuminate 2.5-4.5 x 0.5-1.2 mm, (1-)2-3-nerved from base, persistent. Leaf-stalks 4-10.5 cm, at middle 0.5-1 mm diam., the shallow open ventral sulcus bridged at apex and there charged (nearly always) with a spicule 0.6-1 mm; pinnae 1-jug., the rachis (2-)2.5-5 cm, the interfoliolar segments 5-12 mm; lfts (3-)4-5(-6)-jug., accrescent distally, the unequal first pair 4-13 mm distant from subulate paraphyllidia 0.7-1.5 mm, the blades either subfalcately lanceolate or obliquely elliptic or ovate-elliptic from deeply semicordate base, deltately acute or acuminulate, the distal ones 20-36 x 5-16 mm, 2.2-4.5 times as long as wide, all faintly venose above, sharply so beneath, 5- 7-nerved from pulvinule, the gently incurved midrib dividing blade ±1:2, 4-6-branched on each side from below middle upward, the anterior nerve, when present, weak and short, the inner posterior one incurved-ascending beyond mid-blade, the outer ones progressively shorter, all expiring or weakly brochidodromous within the margin, the cilia ±0.01 mm diam., free through 0.3-1 mm. Peduncles 6-20(-24) mm; capitula without filaments 5-6 mm diam., prior to anthesis moriform, the purplish, prominently 4-keeled fl-buds glabrous; receptacle glabrous; bracts linear-elliptic or -oblanceolate (1.2—)1.5—2.5 x 0.1-0.25 mm, 1-nerved, glabrous or minutely ciliolate; flowers 4-merous 4-androus, in some capitula all bisexual, in others some lower ones staminate; calyx membranous 0.15-0.25 mm, obscurely lobulate; corolla vase-shaped or the smaller ones narrowly turbinate, 1.7-2.6 mm, the ovate 1-nerved, shallowly concave, scarcely thickened lobes 0.5-0.9 x 0.5-0.65 mm; filaments pink or whitish, free to base, exserted 4-7 mm. Pods 1-12 per capitulum, subsessile, in profile oblong obtuse mucronulate, straight or almost so, 20-40 x 10-14 mm, 3-5(-6)-seeded, the very shallowly constricted or straight replum 0.4-0.8 mm wide, armed along back and sides with divaricate straight stramineous, stiffly tapering setae to 2.5-4 mm, the papery brown glabrous, finely reticulate-venulose valves low-colliculate over each seed, naked or with a few small setulae, when ripe breaking up into free-falling indehiscent articles 5-8 mm long; seeds in broad profile obovate-suborbicular 4.6-5.3 x 3.5-4.3 mm, the smooth testa dull brown.

    In thickets, climbing over hedges, and on lava- flows, below 200 m, apparently native on the Windward Is. and on Trinidad and Tobago, thence scattered s. and w. through the Orinoco valley in Venezuela and Colombia to the lower Magdalena valley in Colombia and the Canal Zone in Panama, and through French Guiana to the lower Amazon valley in Amapá and Pará; one record from Amazonas, Brazil (Japurá basin); locally frequent on Puerto Rico, but found there only in recent years and probably introduced, attaining 800 m.—Fl. irregularly through the year.—Paranovillo (Venezuela). Map 47.

    Mimosa casta is very closely related to M. schrankioides, especially so to its var. sagotiana, which has similar calyx but leaflets one third to one half less numerous and to the same degree larger. A modification in the opposite direction, culminating in leaflets reduced to exactly two pairs and these reciprocally dilated, would simulate M. velloziana, which may in reality have arisen in just this way. Although these three species are so much alike in everything but leaf- formula, they appear not to intergrade; I have seen no doubtful or intermediate specimen.

    In the protologue of M. casta Linnaeus cited his own previous descriptions in Hortus upsalensis and Hortus cliffortianus, and also Tabula 28 of the first volume of Jan Commelijn’s Horti medici amstelodamensis. This last depicts a plant grown at Amsterdam, from seed of unknown provenance, that died without producing flowers, but seems certainly the same as that grown in Cliffort’s garden and the species known to Bentham as M. casta. Mimosa no. 2 of Hortus cliffortianus was however a mixture of M. sensitiva (Breynius t. 16), as recognized in Species plantarum, and var. a which corresponds with Commelijn’s plant. In his early work Linnaeus cited M. casta (under polynomials) from Brazil, and his reason for changing this to India (which may mean the West Indies) is not readily explained. In any event, by 1753 Linnaeus must have had another flowering plant which he mistook for M. casta, for in Species plantarum he described the flowers as dimorphic, some decandrous sterile, others decandrous bisexual. The number ten is, of course, incompatible with M. casta, of which all flowers are tetramerous and haplostemonous.

    I am unable to account for this discrepancy in the protologue, but if Wijnand’s lectotypification (as given above) is accepted, the question is academic.

    The application of the epithet casta is not explained. It should perhaps be interpreted as cognate with sensitiva and pudica, the notions of shame, sensibility and chastity being somehow applicable to these plants, of which the leaves shrink back in modesty when touched.