Mimosa lewisii Barneby

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 lewisii Barneby

Type

93. Mimosa lewisii Barneby, Brittonia 37: 136, fig. 5. 1985.—"Brazil. Bahia: mun. Palmeiras, km 232 da rodovia BR-242 para Ibotirama. Pai Inácio, ±20°30'S, 47°21'W, G. P. Lewis (with A. de Carvalho & Hage) 854"—Holotypus, CEPEC 30093!; isotypi, K! NY! Fig

Description

Species Description - Stout or spindling, potentially arborescent shrubs at anthesis (1-) 1.5-5 m, the arching-ascending, early lignescent lenticellate branches and at times some lf-stks erratically armed with stout, basally dilated, straight or recurved, glabrous or gland-sprinkled aculei to 2-8 mm, the cauline ones either infrastipular or intemodal or both, the young stems, lf-stks and commonly all axes of inflorescence in addition minutely villosulous and thinly to very densely charged with gland-tipped setulae to 0.1—0.5 mm, less often to 0.5—1 mm (but villi and setae sometimes confined to lf-stks), the ample multifoliolate lvs bicolored, the lustrous lfts brown-olivaceous above, paler beneath, their margin minutely ciliolate or glandular-fimbriolate, the inflorescence an efoliate or proximally leafy-bracteate pseudoraceme exserted ±1-2 dm from foliage. Stipules ascending, firm or submembranous, ovate-acuminate to narrowly lanceolate 2.5-5 x 0.6-1.6 mm, 1-5- nerved dorsally, persistent. Leaf-stalks of primary cauline lvs 4-13 cm (of diminished and simpler bracteiform upper lvs shorter, no further described), the stout petiole including obese livid pulvinus 8-19 x 0.7-1.5 mm, the longer interpinnal segments 6-12 mm, the ventral groove bridged between pinna-pairs and there with a glabrous or puberulent spinulose spicule 0.7-2 mm; pinnae of primary lvs 6-14(-16)-jug., subequilong except at one or both ends of lf-stk, the rachis of longer ones 3.5-5 cm, its interfoliolar segments 0.6-1 (-1.4) mm; lfts of longer pinnae (27-)30-48-jug., the first pair 0.2-1 mm distant from small conic-subulate paraphyllidia, all in outline linear-oblong obtuse or subapiculate, the larger ones 4.5-6.5 x 0.8-1.4 mm, the firm blades veinless above, subcentrically costate beneath, other venulation scarcely perceptible. Peduncles solitary and 2-3 together, widely ascending (1.5—)2—5(—5.5) cm; capitula squatly ovoid or hemispherical, the lower fls spreading-ascending from receptacle, the whole without filaments 9-12 mm diam., prior to anthesis moriform; bracts linear- or rhombic-lanceolate to 1.5 mm, or sometimes subobsolete; flowers 4- or randomly 5-merous diplostemonous, all bisexual; calyx campanulate 1.3-3.4 mm, its lobes broadly ovate or obtusely deltate, separated by unequal sinuses (0.1-)0.3-0.9 mm deep; corolla greenish-white 4.5-5.5 mm, the firm erect ovate, apically thickened and subcucullate, faintly 3-nerved lobes 1.4-2 mm; filaments whitish, free, nearly 0.3 mm diam., exserted 3-4 mm; anthers (0.55-)0.6-0.8 mm. Pods mostly 1-3 per capitulum, commonly subsessile, broadly linear and often lunately curved 9-13 x 0.7-0.9 cm, at base cuneately tapering into receptacle or rarely into a stipe to 3 mm, at apex attenuate into a triangular-acuminate beak, planocompressed except where colliculate over seeds, either glabrous or minutely puberulent and glandular-setulose overall, the shallowly undulate-constricted replum 0.6-1 mm wide, the stiffly papery, glossy green red-tinged or mahogany-brown valves breaking up when ripe into 9—14(—15) rhombic-elliptic free-falling, individually indehiscent articles 6-12 mm long; seeds ±5.5-6 x 4-4.7 mm, the smooth testa brown or atrocastaneous.

Distribution and Ecology - In campo rupestre, in open woodland on sandstone, and on stream-banks, locally plentiful at (580-)700-1200 m in Chapada Diamantina of centr. and n.-centr. Bahia, Brazil, from Sa. do Curral Feio (10°22'S) through Sas. do Tombador, da Agua de Rega and dos Lençois to Sa. do Sincorá (13°6'S); disjunct at or below 300 m in valleys of rios Vasa Barris and Itapicuru in n.-e. Bahia, and on white dunes at sea level along the coast n. of Salvador.-Fl. XII-III, VI. Map 12.

Discussion

Floral features peculiar to M. lewisii in the context of its group are hemispherical capitula, deeply campanulate, irregularly lobed calyx, long corolla, and stout filaments scarcely twice as long. The species is randomly variable in the distribution, length and density of excretory glands, which may be stemless or elevated on a setular stalk to 3 mm in length, and either massed along the new stems or confined to the ventral ribs of the leaf-stalks. There seem to be no significant differences between the populations found on the coastal lowlands and those of the upland interior. A comparable dispersal pattern is known in Chamaecrista cytisoides (Colladon) Irwin & Barneby var. brachystachya (Bentham) Irwin & Barneby.

Distribution

Brazil South America| Bahia Brazil South America|