Monographs Details: Mimosa leimonias Barneby & Fortunato
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 pedunculosa Micheli
Description:Species Description - Delicately slender unarmed microphyllidious herb from shortly forked caudex, the humifusely radiating stems 1.5—4 dm, bearing in most axils, upward from below middle, a leafy brachyblast and 1 or rarely 2 erect capillary peduncles, the stems, lf-stks and peduncles glabrous or only remotely appressed-setulose, the stipules and lfts setulose-ciliolate but otherwise glabrous, the ellipsoid-subglobose capitula very small. Stipules erect subherbaceous lanceolate 2-3 x 0.6-1 mm, coarsely 3(-5)-nerved, persistent. Leaf-stalks of primary cauline lvs 2-15 x 0.2-0.4 mm, progressively shorter upward along stem, those of brachyblasts mostly 10-15 mm filiform (no further described), the ventral groove shallow open, terminating in a spicule much less than 1 mm; pinnae 1-jug., the rachis of longer ones 2-3 cm, the interfoliolar segments 0.6-1.2 mm; lfts of longer pinnae 20-30-jug., progressively more numerous upward along stem, the small first pair 0.5-0.9 mm distant from subulate paraphyllidia 0.2-0.4 mm, the blades linear-oblong from deeply obtusangulate base, obtuse apiculate, the longer ones ±3.5-5.5 x (0.7-)0.8-1.3 mm, 3.8-5 times as long as wide, all veinless above, beneath slenderly 3-nerved from pulvinule, the midrib dividing blade ±1:2, beyond middle 1-2- branched on each side, the first branch anastomosing with the inner posterior nerve, the outer posterior one very short or obscure, the marginal setae less than 0.1 mm diam. Peduncles 2-4 cm x 0.3 mm; capitula without filaments ±4 mm diam., prior to anthesis moriform, the obovoid fl-buds glabrous 4-keeled; bracts oblong-elliptic, abruptly acute 0.9-1.3 x 0.3-0.5 mm, scarious proximally, ciliolate; flowers 4-merous 4-androus, some lower ones staminate; calyx a fimbriolate-denticulate collar 0.15-0.25 mm long; corollas turbinate 1.5-1.7 mm, the ovate, shallowly concave, dorsally carinate lobes 0.7 x 0.5-0.6 mm; filaments pink, free to base, exserted 3-4.5mm; ovary at anthesis glabrous; pod unknown.

Distribution and Ecology - Creeping among grasses in rich moist campo, at elevation not recorded, known only from the Apa-Aquidabán watershed in depto. Amambay, Paraguay, to be sought in adj. Mato Grosso do Sul, Brazil.-Fl. ±1-11.

Discussion:

Mimosa leimonias is closely related to M. petraea and M. pedunculosa, all three are small, inconspicuously pubescent, unarmed mimosae with much reduced calyx endemic to campos of eastern Paraguay. Of the three, M. pedunculosa is most easily recognized by its short stems, elongate peduncles and relatively large capitula (without filaments 6-7, not ±4 mm diam.). Mimosa leimonias and M. petraea are alike in very small capitula but differ, possibly not specifically, in length of leaf-stalks, leaflets and peduncles (as given in the Latin diagnosis) and consequently in gross aspect. The difference in leaflet-venation described in the diagnosis may be merely a function of leaflet-size, but cannot be ignored at the present stage of our knowledge of this intricate group. Possibly M. leimonias—the epithet is the Greek equivalent of Latin pratensis—is a lush, herbaceous, mesophytic ecotype of the ordinarily suffruticulose M. petraea, which is known to occur close by in Sa. de Amambay.

Distribution:Brazil South America| Mato Grosso do Sul Brazil South America| Paraguay South America| Amambay Paraguay South America|

Narratives:Mimosa leimonias