Monographs Details: Mimosa aguapeia 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.
Synonyms:Mimosa orbignyana Barneby
Description:Species Description - Erect, coarsely few- and large-lvd, unarmed, virgate subshrubs ± 1 mm tall, finely puberulent throughout, the stiff few-branched stems in addition densely pubescent with narrowly ascending and subappressed, scaberulous flagelliform setae to ±0.8-1 mm and the axes of inflorescence and the pods further viscid with fine patent gland-tipped setae to 1-2 mm, the plane thick-textured, dull leaden-green lfts puberulent on both faces, sometimes also setulose dorsally and always setose-ciliolate, the inflorescence a few-branched efoliate panicle of pseudoracemes rising far above the foliage, the fls globosely capitate. Stipules firm, ovate acute 5-9 x 2-4.5 mm, densely appressed-setose dorsally, glabrous striate within, tardily deciduous. Leaf-stalks 6-16 cm, the petiole 1.5-4cm, at middle 2-3 mm diam., the interpinnal segments 1.5-2.5 cm, obscurely grooved ventrally, interpinnal spicules 0; pinnae 3-6-jug., a little accrescent distally, the rachis of longest pair 7-12cm, the longer interfoliolar segments 4-6 mm; lfts of longer pinnae 17-22-jug., except the very lowest subequilong, the first pair 2-3 mm from firm lanceolate paraphyllidia 1.5-2.5 mm, the blades obliquely lance-oblong from shallowly semi-cordate or -rounded base, at apex deltately acute mucronulate, the larger ones 14-19 x 5-6.5 mm, all 4-nerved from pulvinule, the almost straight midrib forwardly displaced to divide blade ±1:2, weakly ±3-branched at and beyond middle, the inner posterior primary nerve incurved-ascending to anastomosis beyond midblade, the outer ones progressively shorter, the whole venation almost immersed on upper face, bluntly prominulous beneath. Peduncles mostly 2-3 per node of inflorescence, at anthesis ± 10 mm, in fruit to 18 mm; capitula prior to anthesis conelike, densely silky-setose, at anthesis without filaments 7-8.5 mm diam., the clavate receptacle less than 2 mm; bracts oblance-elliptic 2.5-3.8 x 0.8-1 mm, silky-barbate dorsally, deciduous with the fls; flowers sessile, 4-merous 8-androus, white, so far as observed all bisexual; calyx pappiform, the tube 0.3-0.5 mm, barbate externally and ciliate, including the fringe of hairs 2-2.4 mm; corolla slenderly trumpet-shaped 3.5-4 mm, the tube glabrous, the ovate cupular lobes 1 x 0.8 mm, densely silky dorsally; filaments united into a stemonozone ± 1 mm, exserted ± 6 mm; ovary shortly stipitate, pilosulous. Pods 2-10 per capitulum, sessile, undulately linear in profile, straight, 35-50 x 6 mm, 5-8-seeded, the replum 0.5-0.7 mm wide, densely ascending-setose and stipitate-glandular, the stiffly papery valves setose like replum, becoming low-convex over each seed, when ripe breaking up into individually dehiscent segments 6-7.5 mm long; seeds compressed-lentiform, in broad view ±5 x 3.5 mm, the testa lustrous brown, minutely pitted, the hippocrepiform pleurogram 3.5 x 2 mm.
Distribution and Ecology - In grassy places (‘vegetação de capim’) at ± 700 m, known only from Sa. do Aguapeí (=Sa. da Pedra) in s.-w. comer of Mato Grosso, Brazil.— Fl. VI-VIII.
Mimosa aguapeia constitutes a link in the replacement series of species endemic to isolated sandstone tablelands about the sources of the Paraguay river. It resembles both of the following species in habit, and M. orbignyana especially in the indumentum of fine pin-shaped gland-tipped setulae on the inflorescence axis and on the fruit, but is clearly different from both in the many fewer pinnae and much larger leaflets, as given in the foregoing key and in the Latin diagnosis. I am indebted to the Director of the Herbarium of Museu Goeldi, Belem, for the loan of the specimens cited.
Distribution:Brazil South America
| Mato Grosso Brazil South America