Monographs Details: Mimosa cryptothamnos 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.
Synonyms:Mimosa eriorrhachis Barneby
Description:Species Description - Terrestrial unarmed shrubs with few stout humifuse woody branches to 1-3 dm and 1-1.7 cm diam., each bearing at tip a cluster of 3-4 ample erect multifoliolate lvs and a stiff virgate leafless (rarely at first node 1 -lvd) pseudoraceme 4-7 mm diam. at base and attaining 7.5-12 dm in height, the cauline and foliar axes densely clothed in basally thickened and lutescent, flagelliform gray-tipped setae to ± 2-4 mm, the firm lustrous brown-olivaceous lfts glabrous facially, pectinately setulose- and minutely villous-ciliolate. Stipules associated with developed lvs firm ovate-triangular 7-13 x 2.5-6 mm, densely setose dorsally, glabrous chocolate-brown within, deciduous, those at leafless nodes or subtending peduncles caducous before anthesis. Leaf-stalks (10-)24-43 cm, the shallowly widely sulcate petiole 3-9 cm, at middle 2-4 mm diam., the longer interpinnal segments 10-21 (-26) mm; interpinnal spicules 0; pinnae (9-) 13-21 -jug., notably decrescent proximally, slightly so distally, the rachis of longer ones 5-11 cm, the longer interfoliolar segments 2-3 mm; lfts of longer pinnae 34-48-jug., the first pair close to pulvinus, all in outline narrowly oblong obtuse, straight or almost so, the larger ones 7-9 x 1.7-2.2 mm, the faint venation obscurely elevated on both faces or only beneath. Peduncles solitary or 2—3 per node, at anthesis 1.5—2(—?) cm, in fruit widely ascending 2-4 cm; capitula globose or squatly ellipsoid, without filaments ± 1 cm diam., prior to anthesis moriform; bracts linear-spatulate ±2-2.5 x 0.5 mm, much shorter than the associated flower; flowers 4-merous 8-androus, some proximal ones staminate; calyx campanulate 0.35-0.5 mm glabrous, its rim charged with setae up to 0.5-1.5 mm; corolla 4.5-5 mm, the funnelform tube glabrous, the concave, apically callous, externally densely setulose lobes 1.2-1.8 mm; filaments pink, monadelphous through ±0.8 mm, exserted 9-10 mm. Pods (not seen fully ripe) ± 1-5 per capitulum, sessile, in profile oblong-elliptic to 25 x 11 mm, 2-4-seeded, the replum ±1.5 mm wide, the fleshy-leathery valves and replum alike densely coated with coarse comma-shaped, appressed and subcontiguous yellowish setulae; dehiscence not seen, but the valves probably falling entire from replum.—Frontispiece (A-C).

Distribution and Ecology - On rocky campo slopes at ± 1000 m, rare and local, known only from the s. end of Chapada dos Veadeiros, near 14°20'S, in e.-centr. Goiás, Brazil.-Fl. XII-II.


Mimosa cryptothamnos is closely related to M. eriorrhachis, vicariant immediately southward on Sa. Geral do Paranã, but is distinguished by stout woody humifuse trunks, longer true petioles, slightly longer and wider leaflets, smaller, long-pedunculate capitula, and especially by small floral bracts, greatly surpassed by the associated flower. In M. eriorrhachis each bract is as long as its flower and covers it in bud, so that the capitulum prior to anthesis is conelike, not moriform as in M. cryptothamnos. The very long and dense comose indumentum of M. eriorrhachis is visually arresting but basically of the same type as in M. cryptothamnos, a little exaggerated in length and density.

Distribution:Brazil South America| Goiás Brazil South America|