Monographs Details: Mimosa atlantica 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.
Scientific Name:Mimosa atlantica Barneby
Synonyms:Mimosa gymnas Barneby
Description:Species Description - Armed shrubs of unrecorded height with stout terete glabrous, decumbent or assurgent, chocolate-brown flowering stems armed between successive nodes, on ribs descending from the lance-ligulate stipules, with a pair of stout broad-based, stramineous brown-tipped, almost straight aculei 3-9 mm, the lf-axes very sparingly strigose with appressed setae ±1 mm, the peduncles a little more densely and shortly strigulose and puberulent, the dry foliage dull brown sub-bicolored, the lfts a little paler beneath than above, glabrous facially, discontinuously setose-ciliate, the plumply ellipsoid, solitary or geminate capitula forming a conspicuously stipulate but efoliate pseudoraceme exserted 2-3 dm from foliage. Stipules firm ascending, narrowly lanceolate 10-13 x 1.2-2 mm, glabrous facially, thinly or remotely setose-ciliate, coarsely 4-5-nerved, persistent. Leaf-stalks 3-5.5 cm x 0.4-1 mm, the narrow ventral sulcus open at apex (spicule 0); pinnae 1-jug., the rachis 8-11 cm, the interfoliolar segments 3-5(-7) mm; lfts 18-21 -jug., the first pair 2-5 mm distant from unequal paraphyllidia (the larger of these exterior, falcately lanceolate 1.5-2.5 mm, 1 -nerved), the blades broadly linear from obtusangulate base, deltately acute, slightly curved forward, those near mid-rachis 12-20 x 3-5.5 mm, 4-4.4 times as long as wide, all 4-nerved from livid pulvinule, the simple midrib displaced to divide blade ±1:2-2.5, the inner posterior nerve expiring well beyond mid-blade, the outer ones shorter, the venation not raised yet faintly perceptible on upper face, bluntly prominulous beneath, the appressed marginal setae ±0.1-0.2 mm diam., free through 0.5-0.8 mm. Peduncles ±2-3 cm; capitula without filaments ±10-12 x 7-8 mm, prior to anthesis moriform, the fl-buds minutely puberulent at tip between four prominent keels; bracts linear-oblanceolate 2.4-2.8 x 0.3 mm, glabrous except for a few minute setular cilia; flowers 4-merous 4-androus, in the one capitulum examined in detail all functionally staminate, the ovary present but the style apparently abortive, filiform and included in corolla; calyx membranous 0.2-0.25 mm, glabrous, the obscurely angulate-lobulate orifice bearing 1-3 minute setulae; corollas narrowly vase-shaped 3.3 mm, the membranous ovate 1-nerved, shallowly concave lobes ±0.8 x 0.7 mm; filaments lilac-pink, free to base, exserted ±8-10 mm; ovary glabrous. Pod unknown.

Distribution and Ecology - On river bank at 150 m, known only from the Atlantic coast of Paraná, Brazil in lat. 26°S (mun. Guaratuba).-Fl. XII-I(-?).


Mimosa atlantica seems morphologically closest to M. gymnas, but differs decisively in stout glabrous stems armed with straight intemodal prickles, in ample leaves, and in lowland Atlantic habitat.

Distribution:Brazil South America| ParanĂ¡ Brazil South America|

Narratives:Mimosa atlantica