Mimosa paupera

Title

Mimosa paupera

Authors

Rupert C. Barneby

Scientific Name

Mimosa paupera Benth.

Description

460. Mimosa paupera Bentham, J. Bot. (Hooker) 4: 372. 1841.—Typus infra sub var. paupera indicatur.

Slender unarmed perennial herbs with several simple terete, procumbent or humifuse stems 1- 5(-7) dm from a branched subterranean caudex surmounting a fusiform or massive cylindric woody root, the stems, lf-axes and peduncles variably but usually only thinly hispid-setose with spreading-ascending or strigose with forwardly appressed, straight tapering or at tip flexuously flagelliform setae to 1-2.5 mm, sometimes in addition minutely puberulent, less often subglabrous, the sparse, very sensitive foliage olivaceous subconcolorous, the firm plane lfts often thinly pilosulous dorsally on side posterior to stout midrib and also exceptionally so ventrally, the proximal pairs very often in addition dorsally appressed-setose, the ellipsoid or subglobose capitula all axillary, none pseudoracemose. Stipules firm erect, lanceolate 3-7(-8) x 0.6-1.1 mm, striately 3-5-nerved, dorsally glabrous or puberulent, setose-ciliate, persistent. Leaf-stalks (5-)7- 30 mm, or of some lower lvs to 5-7 cm, at middle 0.5-0.8 mm diam., shallowly openly sulcate ventrally, espiculate; pinnae 1-jug., ascending in wide V from tip of petiole, the rachis of longer ones 7-45 mm, the interfoliolar segments 0.9-5.5 mm; lfts of longer pinnae 6—15(—19)-, rarely only 4-6-jug., conspicuously decrescent both up- and downward from a point near mid-rachis, the first pair 0.4-1.5 mm distant from subulate paraphyllidia 0.7-2.7 mm, the blades oblong-elliptic or obliquely oblanceolate from broadly shallowly semicordate base, abruptly apiculate or obtuse mucronulate, those near mid-rachis 7-21 x 1.56 mm, 3-4.6(-5.3) times as long as wide, all veinless above, beneath 3-4-nerved from pulvinule, the strong simple midrib displaced to divide blade 1:3-5, the more slender inner posterior nerve expiring beyond mid-blade, the outer 1-2 nerves short and weak. Peduncles all solitary or some in distal axils geminate, mostly 3-8(-9) cm but some late ones at times shorter; capitula without filaments 4.5-6.5 mm diam., prior to anthesis moriform, the obovoid, 4-keeled fl-buds silvery- retrostrigulose; bracts linear or linear-oblanceolate 0.8-2 x 0.2-0.4 mm, glabrous and 1-carinate dorsally, shortly setose-ciliolate distally; flowers 4-merous, the bisexual ones 4-androus and some small lower staminate ones 8-androus, at least in some capitula; calyx submembranous 0.1-0.2 mm, the rim glabrous or minutely ciliolate, the fine weak hairs not over 0.3 mm; corolla narrowly funnelform or subcylindric (the short proximal ones sometimes turbinate) 1.6-2.6 mm, retrostrigulose almost or quite to base, the ovate, scarcely thickened 1-nerved concave lobes 0.5-0.75 mm; filaments pink-lilac, obscurely united at very base, exserted (4-)4.5-6.5 mm. Pods (not well known) ±5-20 per capitulum, sessile, in profile narrowly oblong ±10-16 x 3-4 mm, abruptly apiculate, the shallowly constricted replum 0.3-0.4 mm diam., hispid along back and sides with ascending smooth setae 1-1.5 mm, the papery valves coarsely retrostrigulose with somewhat shorter comma-shaped setulae not concealing the face of valves, these low-colliculate over each of 2—4(-5) seeds, when ripe breaking up into free-falling, rhombic-elliptic articles ±3-3.5 mm long.

In the context of subser. Reptantes a syndrome of generally diffuse stems, slender petioles, conjugate and short, relatively few-foliolate pinnae characterizes this variable yet seldom misidentified species. The leaflets of each pinna are nearly always much diminished both up and downward from near mid-rachis, forming when fully displayed a composite blade of elliptic outline.