Monographs Details: Mimosa prorepens 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 prorepens Barneby
Synonyms:Mimosa accedens Barneby, Mimosa reflexa Harms ex Glaz., Mimosa planaltoana Harms ex Glaz.
Description:Species Description - Unarmed, functionally herbaceous subshrubs, the homotinous stems (4-)5-15 dm, procumbently radiating from a xylopodium and distally incurved or assurgent, simple or branched above middle, the cauline and foliar axes at once villosulous with fine incurved plain hairs and hispid with subhorizontal tapering yellowing setae to 2- 4(-5) mm mixed or not with shorter glandular setulae, the lfts villous-ciliolate esetose, the pod with some glandular setulae, the small plumply ellipsoid capitula axillary to reduced distal lvs or forming a well exserted pseudoraceme. Stipules either widely spreading-ascending or reflexed, lanceolate or linear-attenuate (4.5-11.5 x 0.5-1.6 mm, indistinctly 5-7-nerved, setose-ciliate, persistent. Leaf-stalks of primary cauline lvs 5.512.5 cm (of distal lvs often shorter, no further described), the petiole 4-11 x 0.7-1.4 mm, the longer interpinnal segments 4-7(-8) cm, the ventral groove bridged between pinna-pairs but spicules 0: pinnae of longer lvs 11-26-jug., decrescent proximally but scarcely so distally, the rachis of longer ones 20-35(-40) mm, the longer interfoliolar segments 0.5-1.2 mm; lfts of longer pinnae (26-)28-50-jug., the first pair 0.3-0.7 mm distant from the minute or rudimentary paraphyllidia, all in outline narrowly oblong obtuse, the longer ones 2.5-4.5 (-5.5) x 0.5-1 mm, all glabrous lustrous on upper or on both faces. Peduncles solitary or geminate (1.5—)2—5.5 cm; capitula without filaments 10-15 x 8-10 mm, prior to anthesis either conelike or hispidulous with emergent bract-tips; bracts linear-oblanceolate 1.5-3.2 x 0.25-0.4 mm, setulose on back and margin; flowers 4-merous 8-androus; calyx 0.4-0.5 mm, externally glabrous, the rim weakly setulose-ciliolate, the tube and cilia together ± 1/3 as long as corolla; corolla 3.1-3.6 mm, the narrowly funnelform tube glabrous, the ovate concave lobes ±0.8 mm, densely setulose dorsally. Pods (not seen fully ripe) 1-4 per capitulum, subsessile, in profile broadly linear piano-compressed ±40-45 x 9-10 mm, shortly cuspidate at apex, the replum ±1 mm wide, the valves only ±0.1 mm thick in section but differentiated into papery endocarp and lustrous livid exocarp of subequal thickness, the valves and replum alike finely villosulous and thinly hispid with ascending yellowish plain setae to 2-2.5 mm mixed with random delicate and shorter gland-tipped setulae, the dehiscence and ultimate nature of ripe valves unknown.

Distribution and Ecology - In campo, 950-1150 m, apparently localized in highland s.-e. Goiás, Brazil, on Sa. Geral do Paranã within a radius of ± 10 km of S. João da Aliança near 14°35-50'S, and in the upper Corumbá basin at 15°50'S.—Fl. X-IV.

Discussion:

Mimosa prorepens is one of three planaltine Pachycarpae with procumbently humifuse herbaceous stems arising annually from woody roots, and in one or other focus of its apparently bicentric range it is sympatric with each of the other two. The fruits of none of these three mimosas are completely known, and it is possible, but I think unlikely, that they are less closely related than I have assumed from common habit of growth and from similarities in stipule, foliage, flower, and at least shortly monadelphous filaments. The differential characters of these habitally similar species, M. humivagans sympatric on the sources of rio Paranã north of the Federal District and M. pseudofoliolosa potentially so on the upper Corumbá south of the District, are mentioned at length under the protologues of these species. Outside the humifuse group I find suggestive similarities between M. prorepens and M. accedens, especially in aspect and relatively thin texture of the nearly mature pod. The latter differs decisively, however, in virgately erect stems and glabrous corolla-lobes.

Distribution:Brazil South America| Paraná Brazil South America| Goiás Brazil South America|

Narratives:Mimosa prorepens