Monographs Details: Mimosa thomista 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 thomista Barneby
Description:Species Description - Macrophyllidious unarmed subshrubs from woody root, the solitary or few purplish-castaneous, simple or distally few-branched wandlike stems ± 1 (when protected attaining 2) m, setose like lf-stks with straight, widely loosely retrorse setae to 1.5-2.5 mm, amply foliate to middle or beyond and thence passing into a simple efoliate pseudoraceme of globose capitula 2-5 dm, the axes of inflorescence retrorsely strigulose and minutely puberulent, the plane coriaceous, concolorously brown-olivaceous lfts glabrous except for marginal setae, reticulately venulose on both faces. Stipules firm erect, lanceolate 7-10 x 1.2-2 mm, glabrous facially, coarsely 3-nerved, setose-ciliate, persistent. Leaf-stalks 3-6.5 cm, at middle 1.3-1.7 mm diam., the ventral groove broad and very shallow; spicules 0; pinnae 1-jug., the rachis of each 5-8 cm, the laterally compressed, ventrally 2-costate interfoliolar segments (5-)7-15 mm, the narrow sulcus between ventral ribs interrupted at insertion of lfts by a corneous thickening, the pulvinules short, transversely dilated, nigrescent; lfts 5-8-jug., a little decrescent proximally, the first pair 1.5-2.5 mm distant from lanceolate (unequal) paraphyllidia 1-2.5 mm, the blades obliquely broad-lanceolate and deltately acute to ovate or elliptic-obovate and obtuse mucronulate, the longer ones 33-40 x 13-21 mm, 1.3-2.6 times as long as wide, all coarsely 5-7 nerved from pulvinule, the midrib displaced to divide blade ±1:2, the lateral primary nerves brochidodrome shortly within the corneous pallid margin, all primary nerves several-branched and the branches anastomosing into an open irregular reticulum, the larger areoles ±1-1.5 mm diam., the single file of cilia forwardly appressed and free through ±1.5-2 mm. Peduncles fasciculate by 2-3, in fruit 1-2 cm; capitula not seen in flower, but shortly before anthesis moriform 8 mm diam., the obtuse 4-angulate and vertically 4-sulcate fl-buds microscopically papillate glabrous; bracts linear-oblanceolate 1.5-2 x 0.20.3 mm, glabrous dorsally, setose-ciliolate; flowers (described from annotinous remnants) 4-merous 4-androus; calyx pappiform-paleaceous 2.5-3 mm, the lobes divided nearly or quite to base into slender stramineous setae; corolla 4-4.2 mm, narrowly funnelform, the subcorneous cymbiform, dorsally carinate lobes 1.2-1.4 x 0.5-0.6 mm; filaments free to base, not seen entire. Pods ± 10-25 per capitulum, sessile, forming a round but compressible sphere ±2733 mm diam., in outline oblong-elliptic 8-17 x 5-7 mm, (l-)2-4-seeded, the replum 0.7-1 mm wide, at apex either abruptly obtuse or stoutly cuspidate, armed with pluriseriate erect stramineous setae of various calibers, the longer ones 4-5 mm, the papery valves separating when ripe from replum and breaking up into biconvex glabrous, weakly venulose articles 3-4.5(-5) mm long; seeds not seen.

Distribution and Ecology - In campo rupestre, sometimes sheltered in pockets of sandstone caprock, near 1200 m, known only from S. Thomé das Letras, ± 30 km n. of Caxambú, near 21°45'S, 45°W on n. slope of Sa. da Mantiqueira in s. Minas Gerais, Brazil. -Fl. IV-V(-?).

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Distribution:Brazil South America| Minas Gerais Brazil South America|

Narratives:Mimosa thomista