Monographs Details: Mimosa
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.
Description:Species Description - Perhaps a wandlike shrub with slender defoliate trunk branched distally, the homotinous branchlets, pinna-rachises and continuous lft-margin densely strigose with coarse tapering, microscopically scaberulose setae, the dark brown lfts glabrous ventrally, puberulent dorsally (the proximal ones of each rachis more densely so), the inflorescence unknown. Stipules linear-lanceolate 3—4 mm, dorsally pubescent like stem, deciduous. Leaf-stalks reduced or almost so to hard pulvinus; pinnae 1-jug., the incurved rachis 8-12 cm, the interfoliolar segments 1.5-2 mm; lfts ±40-50-jug., densely imbricate and gradually decrescent near each end of rachis, in outline falcately lanceolate from semicordate base, acute, those at mid-rachis ±9-10 x 2-2.5 mm, 4-4.5 times as long as wide, all nerveless above, beneath pallidly 5-nerved from pulvinule, the simple midrib strongly displaced forward, the inner posterior nerve expiring just short of apex, the outer ones successively shorter, the marginal setae at base ±0.2 mm diam., free for 2-2.5 mm.
The barren specimen described above suggests a species related to M. hypoglauca, M. papposa, and M. callithrix. It resembles the last in the minutely puberulent setae, but differs in subsessile leaves. Mimosa papposa and M. hypoglauca have pinnae only half as long, and smooth setae. Nearly akin and possibly conspecific is Irwin 31431 (NY) from northwest Bahia at about the latitude of Natividade (described above sub no. 394bis). This is similar in scaberulous setae, sessile leaves and very long pinnae, but has glaucescent, straight (not falcate) leaflets puberulent on both faces.