Monographs Details: Mimosa hatschbachii 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
Description:Species Description - Procumbent or diffuse, freely branched, delicately microphyllidious shrublets ± 3-5 dm armed on internodes and randomly on dorsal or lateral ribs of lf-stks with recurved brownish-stramineous aculei 0.5-2 mm, the slender homotinous branchlets and lf-axes viscid-villosulous with minute forwardly incurved hairs and very slender erect gland-tipped setulae to (0.05-)0.1-0.4 (-0.5) mm, the tiny thick-textured olivaceous concolorous lfts facially glabrous, gland-ciliolate, the small, plumply ellipsoid or globose capitula solitary or geminate on peduncle as long or nearly twice as long as the associated lf. Stipules firm, green when young, lanceolate, deltate or broadly triangular 0.7-3.2 x 0.5-1 mm, persistent. Leafstalks 8-32 mm, the petiole (1—)2—6 x 0.25-0.45 mm, the interpinnal segments 1.5-7 mm, the narrow ventral groove continuous between pinna-pairs (spicules 0); pinnae 4-6(-7)-jug., subdecrescent proximally, the rachis of longer ones 3.5—9(—12) mm, the pulvinus scarcely differentiated, the small ovate paraphyllidia inserted close to primary lf-stk; lfts of longer pinnae 6-9(-10)-jug., opposite and subequilong, the first pair 0.4-0.8 mm distant from paraphyllidia 0.2-0.3 mm, the blades oblong or oblong-elliptic obtuse, the longer ones 1-2 x 0.3-0.9 mm, 2.1-4.2 times as long as wide, either veinless externally or faintly 3-nerved dorsally. Peduncles 1.5-5.5 cm, either simply glandular-setulose or also setaculeate; capitula without filaments 4.5-5 mm diam., prior to anthesis moriform, the obtuse fl-buds thinly puberulent, or minutely viscid-setulose or -granular; bracts oblanceolate acute ±1.5-2 mm, the blade puberulent or viscid-setulose dorsally; flowers 4-merous 8-androus, all or most bisexual; calyx membranous campanulate 0.3-0.5 mm glabrous, the rim asymmetrically short-denticulate; corolla narrowly turbinate 2.2-2.6 mm, the triangular-ovate thin-textured 1-nerved lobes 0.65-1 x 0.5-0.7 mm, sometimes bullately thickened at tip; filaments pink, monadelphous through (0.3-)0.4-1.5 mm, exserted 3-5 mm. Pods several per capitulum, sessile, in profile oblong-elliptic, including the long, dorsoventrally compressed terminal cusp (10-) 14-16 x 4 mm, (2-)3-4-seeded, the shallowly constricted replum 0.5-0.6 mm diam., the brown papery valves bullately elevated over each seed, together with replum thinly puberulent and glandular-setulose overall, when ripe breaking up into free-falling, individually dehiscent articles 2.5-3 mm long (the terminal one longer); seeds compressed-obovoid ±2.8 x 2.1 mm, the smooth testa fuscous-castaneous.

Distribution and Ecology - In stony campo and about basalt outcrops, near 1000 m, known only from the heights of Sa. Geral in mun. Guarapuava (Rio Campo Real; Fda. Capão Redondo; Canta Galo), near 25°20'S in s.-centr. Paraná, Brazil.—Fl. VIII-XI.

Discussion:

This delicately attractive little shrub mimosa resembles M. pseudotrachycarpa in armed stems and in diminutive foliage, but is weakly diffuse, not stiffly fruticulose, has more numerous pairs of pinnae, and evidently, often strongly monadelphous stamens. It is dedicated with gratitude and admiration to Dr. Gert Hatschbach of Curitiba, whose collections of mimosa, most generously shared with NY, have contributed enormously to this revision.

Distribution:Brazil South America| ParanĂ¡ Brazil South America|