Monographs Details: Mimosa jacobita 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
Scientific Name:Mimosa jacobita Barneby
Synonyms:Mimosa bipennatula Barneby, Mimosa xanthocentra var. subsericea (Benth.) Barneby
Description:Species Description - Xeromorphic unarmed microphyllidious shrublet, the prostrate defoliate older branches crooked wiry blackish, the homotinous ones assurgent, densely leafy, these and lf-axes densely strigulose with appressed, tapering smooth setae to l-2(-2.5) mm, the very narrow and closely imbricate olivaceous lfts glabrous above, strigose beneath, finely continuously callous-marginate and appressed-ciliate, the small obovoid-ellipsoid capitula either solitary or geminate, short-pedunculate in the axil of a few distal lvs and well surpassed by them. Stipules stiffly erect, linear-setiform 1.5-4.5 x 0.2-0.4 mm, livid-castaneous and either glabrous or microscopically puberulent dorsally, 1-nerved, persistent. Leafstalks including hard, little-swollen pulvinus (1-) 1.5-3 x 0.4-0.6 mm; pinnae 1-jug., strictly ascending, the rachis 16-28 mm, the interfoliolar segments 0.3-0.5 mm; lfts (28-)30-48-jug., decrescent at each end of rachis, the first pair 0.4-1 mm distant from pulvinus (paraphyllidia 0), all in outline narrowly linear from obliquely tmncate base, acute or subacute, those near mid-rachis (2.5-)3-4.5 x 0.3-0.6 mm, ±6-9 times as long as wide, all smooth veinless above, beneath weakly subcentrically 1 -nerved. Peduncles 5-8 mm; capitula without filaments 6-7 x 3.5-4 mm, prior to anthesis silky-hispidulous; bracts linear-elliptic 0.8—1.5 x 0.3—0.4 mm, dorsally thinly strigulose, ciliolate; flowers 4-merous 4-androus, many lower ones staminate; calyx paleaceous-pappiform 1.3-1.9 mm, the lobes deeply setaceous-decompound; corolla membranous, narrowly turbinate 4-angulate 1.6-2.3 mm, the concave lobes 0.5-0.8 x 0.3-0.4 mm, delicately keeled dorsally and thinly pilosulous near margin; filaments pink, monadelphous through 0.3-0.5 below the ovary, exserted 4.5-7.5 mm. Pods 1(-?) per capitulum, sessile, narrowly oblong ±20 x 4.5-5 mm, 4-seeded, the undulately constricted replum ±0.4 mm wide, strigose-hispidulous overall with ascending pallid-based setae to 1.5-2 mm, the papery brunnescent valves retrostrigulose and often also minutely puberulent, breaking up when ripe into low-biconvex free-falling articles 4.5-5 mm long; seeds not seen.

Distribution and Ecology - Locally plentiful on sandstone outcrops, 800-950 m, s. slope of Serranía de Santiago, near 18°25'S, 59°W, in Santa Cruz, Bolivia.-Fl. VI-?

Discussion:

This little crooked shrublet has foliage of the year crowded at the ends of brittle leafless branchlets and is in consequence very different in facies from the virgate, functionally herbaceous, equably foliate M. xanthocentra var. subsericea, of which it has the technical floral and fruiting characters. In ecology and in extremely narrow, marginate leaflets stacked contiguously along the pinna-rachis like the barbs of a bird’s feather it resembles M. bipennatula, known only from another residual rock-mass far distant to the northeast in southern Mato Grosso. The latter has erect trunks, leaflets nearly twice as many per pinna, 5-7 (not l)-nerved stipules, and a calyx only half as long.

Distribution:Bolivia South America| Santa Cruz Bolivia South America|

Narratives:Mimosa jacobita
Multimedia: