Monographs Details: Mimosa chartostegia 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 micropteris Benth.
Description:Species Description - Precociously flowering shrubs attaining 2.5 m, the stiff, prominently 8-10-ribbed, internally pithy stems and the lf-axes thinly, the inflorescence more densely strigose with appressed or narrowly ascending, basally dilated, mostly comma-shaped setae ±0.5-1 mm mixed with scattered minute puberulence, nowhere glandular, the thick-textured subconcolorous lfts glabrous lustrous, the plumply ovoid-globose capitula densely shortly pseudoracemose either from distal lf-axils, when immersed in foliage, or terminal to branchlets, when shortly exserted. Stipules firm lance-ligulate obtuse mucronate 4-9 x 1-1.5 mm, commonly 3-nerved beyond middle, tardily deciduous. Leaf-stalks 3.5-7 cm, rounded dorsally, grooved ventrally and laterally, the petiole including obese livid pulvinus 6-15 x 0.7-1.4 mm, the interpinnal segments 3.5-8(-10) mm, the ventral groove bridged between pinnae but espiculate; pinnae 7-9-jug., accrescent distally, the rachis of longer ones (1.5—)2—3.5 cm, the longer interfoliolar segments 0.6-1.2 mm; lfts of longer pinnae 25-33-jug., decrescent only at each end of rachis, the first pair 0.4-0.7 mm distant from small lanceolate paraphyllidia, all in outline narrowly oblong from angulate base, callous-mucronate at apex, the longer ones 2-4.5 x 0.5-1 mm, 3.5-4.5 times as long as wide, the midrib of all only a little displaced and subimmersed. Axis of pseudoracemes, including peduncle, 2-5 cm, mostly (2-)3-5-capitulate; peduncles solitary or geminate, at anthesis 5-10 mm; capitula prior to anthesis conelike 7.5-8.5 mm diam., the imbricate bracts concealing the densely silvery-strigulose fl-buds but deciduous as these expand, the capitulum at anthesis becoming, without filaments, 8-9 mm diam.; bracts lanceolate 3-5.5 x 0.7-1.1 mm, downwardly attenuate and glabrous at base, the firm brownish-stramineous incurved blade puberulent dorsally near middle, glabrate at tip, serrately setose-ciliolate, bluntly 1-nerved; flowers 4-merous 4-androus, some lower ones small and either imperfect or sterile, the rest subequilong but only a few distal ones bisexual; calyx paleaceous 2-2.7 mm, 4-cleft nearly to base, the lobes deeply setose-decompound; well-developed corolla narrowly funnelform 2.6-3.3 mm, the cymbiform, internally purplish, externally densely antrorse-strigulose lobes 1-1.1 x 0.55-0.65 mm; filaments pink, aging whitish, free at base, exserted 5-6.5 mm; ovary strigulose; pod unknown.

Distribution and Ecology - In stony, sometimes moist campo near 850-1100 m, known only from the Atlantic-Paraguai divide in lat. 25°10'-30°S in e. Paraná, Brazil (Serrinha, e. of Ponta Grossa; Sa. do Caeté in mun. Rio Branco do Sul; Sa. S. Luis do Purunã in e. mun. Palmeira).—Fl. VII-VIII.

Discussion:

Mimosa chartostegia resembles M. micropteris in habit of growth, but is distinguished at a glance by the conelike capitula.

Distribution:Brazil South America| Paraguay South America|

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