Monographs Details: Mimosa guaviarensis 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
Synonyms:Mimosa pudica L.
Description:Species Description - Microphyllidious subshrubs of unknown stature, armed at nodes with a pair of straight, spreading-ascending stramineous infrastipular aculei 2-6.5 mm and also on some internodes with a downwardly displaced infrapetiolar one, the stiff, simply virgate, closely foliate stem passing upward into an efoliate (perhaps largely hysteranthously leafy) pseudoraceme of small ovoid-ellipsoid capitula, except for facially glabrous lfts silky throughout with fine, narrowly ascending setae to 2-2.5 mm, the small lfts concolorous and closely inbricate. Stipules firm erect lanceolate 2.5-6 mm, setose dorsally, striate glabrous within, persistent. Leaf-stalks including firm pulvinus 4-6 x 0.4-0.5 mm, espiculate, some charged on dorsal rib with a few random ascending aculeoli; pinnae 1-2-jug., when 2-jug. subpalmately so, the interpinnal rachis not over 1 mm; rachis of pinnae 14-21 (-25) mm, the interfoliolar segments 0.4-1 mm; lfts (14-)16-27- jug., a little decrescent at each end of rachis, the first pair close to pulvinus, the blades linear acute from proximally auriculate base, those near mid- rachis 4-5.5(-7) x 0.5-0.9 mm, ±6-8 times as long as wide, all veinless above, beneath 3-5- nerved from pulvinule, the nearly centric midrib pinnately 2-3-branched on each side from near middle upward, the posterior primary nerves much shorter, the margin finely discontinuously appressed-setose-ciliate. Peduncles solitary at base of inflorescence but distally fasciculate by 2-4, becoming 10-17 mm; capitula without filaments ±5x4 mm, prior to anthesis hispidulous with shortly emergent bracteal cilia; bracts linear-attenuate 1.5-2 x 0.2 mm, 1-nerved, glabrous except for 2-3 setulae on each margin; flowers 4-merous 4-androus; calyx an obscure collar not over 0.1 mm; corolla turbinate-campanulate ±1.8 mm, the membranous ovate 1-nerved lobes ±0.5 mm, hispidulous dorsally; filaments (pink) free to base, exserted ±3 mm. Pods to 10 per capitulum, sessile, in outline undulately narrow-oblong 6-12 x 3.5 mm, 2-4-seeded, the constricted replum 0.25 mm diam., armed on dorsal and lateral ribs with divaricate setae 0.5-3 mm, the papery brown valves low-convex over each seed, thinly minutely puberulent and yellow-granular, when ripe breaking up into free-falling articles ± 3 mm long.

Distribution and Ecology - In savanna near 240 m, known only from the upper Guaviare valley near 72°40'W in n.-w. Vaupés, Colombia.-Fl. X-XII(-?).

Discussion:

Mimosa guaviarensis appears closely related to M. pudica, to which Killip referred the type- collection, but it differs in stiffly virgate growth-habit, and especially in the small, shortly petiolate leaves crowded along the stem. Cuatrecasas recorded the plant as frutex, but did not note its stature. The specimens suggest a suffruticose wandlike mimosa of a type common in campo and cerrado habitats south of Amazonia. No Colombian mimosa at all closely resembles it.

Distribution:Colombia South America| Vaup├ęs Colombia South America|