Monographs Details: Mimosa regina 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 regina Barneby
Synonyms:Mimosa rhodostegia Barneby, Mimosa manidea Barneby
Description:Species Description - Unarmed pachycaulous trees attaining 4 m with trunk nearly 1 dm diam. and densely leafy hor- notinous branches to 1.5 cm diam., these terminating in a massive, shortly exserted simple pseudoraceme of large, plumply globose-ellipsoid capitula subtended by ample dilated bracteiform stipules, the stems and lf-stk pilose with flagelliform setae to 0.5-1 mm mixed with fine short villi and short gland-tipped setulae, the very numerous tiny lfts glabrous facially, minutely villous- and glandular-ciliolate. Stipules ovate- or broadly lance-acuminate 25-30 x 7-13 mm, the lower ones connate behind the petiole, the upper free, the firm blades densely flagelliform-setose externally, glabrous castaneous within, the venulation immersed, the blades early dry deciduous. Leaf-stalks crowded toward tip of branches 12-20 cm, the petiole with pulvinus 7-12 x 1.5-2 mm, the longer interpinnal segments 4-7 mm, the shallow ventral sulcus weakly bridged between pinna-pairs but spicules 0; pinnae 25-32-jug., strongly decrescent downward in proximal ¼-blade, the longer distal ones 3.5-5.5 cm, the longer interfoliolar segments 1-1.5 mm; lfts of longer pinnae 35-47-jug., the first pair close to pulvinus (paraphyllidia 0), all in outline oblong obtuse, at base minutely cordate on both sides, the longer ones 3.5-4.5 x 0.8-1.3 mm, the firm plane blades veinless above, beneath 3-nerved from pulvinule, the centric costa weakly branched distally. Peduncles mostly paired and often subtended by a nascent lf shorter than themselves, at anthesis 5-8 cm; capitula without filaments ±25 x 20 mm, prior to anthesis densely yellowish-setose; bracts spatulate-oblanceolate 7-9 x 1.5-0.8 mm, dorsally above middle densely yellowish-setose and -setose-ciliate; flowers 4-merous 8-androus, the lower ones staminate and slightly shorter than the rest; calyx shallowly campanulate 0.6-0.8 mm, obscurely lobulate, each lobe bearing a short gland-tipped setula, otherwise glabrous; corolla tubular-funnelform 7-8 mm, the tube glabrous, the ovate lobes ±1.4 mm, distally concave and subcallose, densely setulose dorsally; filaments pink, monadelphous through ± 1 mm around stipe of ovary, the longer ones exserted 13-17 mm; pod unknown.

Distribution and Ecology - On sandstone outcrops in cerrado or campo rupestre, known only from the type-locality on Chapada dos Veadeiros at a point 20 km n. of Alto Paraíso, near 1250 m, in e.-centr. Goiás, Brazil.-Fl. III-IV.

Discussion:

A spectacular mimosa, notable for its pachycaul habit, very large but early deciduous bracts and stipules of firm texture, dorsally setose and glabrous within. It resembles M. rhodostegia in amplitude of bracts, but in growth-form and in coarse setose indumentum it seems closer to the nearly sympatric M. manidea. From this it differs strikingly in the internally glabrous and deciduous bracts and stipules, more numerous leaflets per pinna, and longer flowers.

Distribution:Brazil South America| Goiás Brazil South America|

Narratives:Mimosa regina