Monographs Details: Mimosa monadelpha Chodat & Hassl.
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 - Erect unarmed subshrubs 5—10 dm, the stems at anthesis defoliate toward base, densely foliate and usually branched distally into a pyramidal panicle of subglobose capitula, the stems, lf-stks of palmatipinnate lvs and all axes of inflorescence commonly densely gray-puberulent and pilose with fine, either shorter ascending or longer spreading, lutescent setae to 1-2 mm long and at base to 0.1-0.15 mm diam., rarely nearly glabrous throughout, the dried foliage dull dark brown, the thin-textured lfts subconcolorous or livid beneath, glabrous on both faces, discontinuously setose-ciliate, the capitula mostly axillary to coevally expanding lvs, some late ones shortly pseudoracemose. Stipules narrowly lance-attenuate 4-7 x 0.5-0.75 mm, strongly 1-nerved, either puberulent or glabrous dorsally, setose-ciliolate, persistent. Petiole of primary cauline lvs 1-3 cm, at middle 0.65-1.4 mm diam., that of some smaller rameal lvs shorter; pinnae of larger lvs 3-4-jug., of some diminished distal lvs 2-jug. (no further described), the pairs of pulvini subcontiguous, the lf-rachis 2-4 mm; rachis of longer pinnae 3.5-7 cm, the longer interfoliolar segments 1.5-3 mm; lfts of longer pinnae 24-32- jug. (of lowest lvs often fewer), decrescent proximally, the small unequal first pair 0.1-0.5 mm distant from subulate paraphyllidia 0.3-1.3 mm, the blades narrowly oblong from obtusangulate base, abmptly apiculate, those at and beyond mid-rachis 4.5-12 x 1.2-3.5 mm, 3—4.3 times as long as wide, all weakly (2-)3-5-nerved from pulvinule, the simple midrib displaced to divide blade 1:1.5-2, the inner posterior nerve expiring beyond mid-blade, the outer ones much shorter, the venation on upper face fully immersed and often imperceptible, on lower face either discolored or faintly raised. Peduncles solitary or occasionally geminate (7-) 10-29 mm; capitula without filaments 6.5-8 mm diam., prior to anthesis moriform, the receptacle glabrous, the 4-sulcate fl-buds microscopically papillate at tip; bracts linear or linear-spatulate 1.4-2.4 x 0.25-0.4 mm, 1-nerved and glabrous dorsally, setulose-ciliolate toward tip; flowers 4-merous 4-androus, some proximal ones staminate and smaller; calyx paleaceous pallid (1-) 1.3-1.9 mm, the glabrous brown tube 0.2-0.3 mm, the lobes deeply decompound; corollas narrowly funnelform (2-)2.3-3 mm, the comeously thickened cymbiform lobes 0.8-1.1 x 0.5-0.65 mm; filaments pink, monadelphous through 1.2-1.4 mm, exserted 4.5—6.3 mm. Pods ±2—6 per capitulum, sessile, in profile oblong 12-24(-25) x 5.5-7.5 mm, broadly rounded at each end, mucronulate at apex, 2-4-seeded, the shallowly constricted replum 0.3—0.8 mm wide, either densely setose with pluriseriate ascending stramineous setae to ±1.5 mm or appressed-setulose, the papery valves either densely hispid with similar but more widely incurved-ascending setae to ±3 mm or only thinly strigose, when ripe breaking up into free-falling, individually dehiscent articles 3-5.5 mm long; seeds (few seen) transverse, compressed-rhomboid-obovoid, in wide profile ±4.5-6 x 3.5—4.5 mm, the smooth testa lustrous brown.
Mimosa monadelpha is closely akin to M. lupinoides, but has stems twice as tall, has six to eight rather than exactly four pinnae borne subpalmately at tip of each leaf-stalk, and has nearly twice as many leaflets per pinna, these only about half as wide. Two readily distinguishable pubescence forms have been described.