Monographs Details: Mimosa struthionoptera 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
Synonyms:Mimosa densa Benth.
Description:Species Description - Amply leafy unarmed tree 4 m, of unknown girth, the stout, densely leafy homotinous branches together with short exserted pseudoraceme of plumply ovoid capitula to 3-3.5 dm, the stems and foliage densely softly gray-villous and viscidulous with erect silvery hairs and yellowish pin-glands ±0.3-0.5 mm intermixed with random (beneath capitula crowded) fine plain rufescent setae to 1-1.5 mm, the lfts villosulous on both faces, glandular-ciliolate. Stipules (early dry caducous, consequently little known) lance-acuminate 9-12 x 1-1.5 mm, the firm blades glabrous castaneous within. Leaf-stalks ascending at narrow angles to the stem, 11-17 cm, the petiole including (or largely composed of) obese gray-velutinous pulvinus 9-12 mm, the longer interpinnal segments 5-7 mm, the ventral groove continuous between pinna-pairs (spicules 0); pinnae 22-24-jug., strongly decrescent proximally but scarcely so distally, the rachis of longer ones 4.5-5 cm, the interfoliolar segments 0.7-1 mm; lfts of longer pinnae 50-58-jug., the first pair not more than 0.3 mm distant from minute villosulous paraphyllidia, all narrowly oblong obtuse, the larger ones ±4-4.5 x 1 mm, the blades veinless above, faintly 3-nerved beneath. Peduncles solitary and geminate 4-5 cm; capitula without filaments ±20 x 14 mm, prior to anthesis loosely conelike; bracts linear-oblanceolate 5-6 mm, both setulose and glandular dorsally, surpassing the flower until full anthesis; flower with calyx shallowly campanulate ±0.4 mm, the orifice ciliolate with weak, sometimes gland-tipped setulae to ±0.8 mm; corolla 5-6 mm, the slenderly funnelform tube externally glabrous, the ovate concave, apically callous and dorsally densely setulose lobes ± 1 mm; filaments pale pink, monadelphous through ± 1 mm, exserted to 11 mm; pod unknown.

Distribution and Ecology - On rocky slopes at or perhaps above 1200 m, known only from the type-locality on the Tocantins slope of Chapada dos Veadeiros, near 14°S in e.-centr. Goiás, Brazil.—Fl. IX-X(-?).

Discussion:

Short soft, partly glandular—and on leaf-pul- vini extremely dense and plush-like—indumentum of the foliage, extended (not rosette-forming) annual branches, relatively long crowded pinnae and tiny imbricate leaflets characterize this visually striking arborescent mimosa. In habit it closely resembles M. rheiptera, which differs in predominantly yellow-setose pubescence and longer peduncles. Field observation of growth-forms and dispersal on and between rock-piles in Tocantins National Park are required before the classification of these and related forms can be worked out. The epithet refers to the leaves, fancifully likened to ostrich plumes.

Distribution:Brazil South America| Goiás Brazil South America|