Monographs Details: Mimosa minarum 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 brevipinna Benth.
Description:Species Description - Functionally herbaceous subshrubs 3-7 dm with stiff few-branched stems ascending from woody rootstock, except for glabrous faces of lfts and glabrous corollas viscid-villosulous throughout with fine erect gland-tipped setulae 0.5-1.2 mm intermixed with underlying puberulence (sometimes almost lacking) and few, randomly scattered yellowish setaculei to 1 mm, the foliage olivaceous concolorous, the small plane lfts resinously lustrous on both faces, thinly glandular-fimbriolate, the globose capitula solitary and geminate in distal lf-axils on peduncle sub-equaling or shortly surpassing the subtending lf. Stipules thinly herbaceous ovate- or broadly lance-acuminate 2-4.5 x 1.2-2.5 mm, 2-5- nerved from base, the stout midrib excurrent as a mucro, the lateral nerves much shorter. Leafstalks (2.5-)3-6.5 cm, the petiole 3—12(—14) x 0.4-0.5 mm, less than twice as long as the interpinnal segments, these 3-8 mm; no interpinnal spicules; pinnae 6-10(-12)-jug., a little accrescent distally, the rachis of longer ones (5-)6—12 mm, the interfoliolar segments 0.5-1.1 mm; lfts of longer pinnae (8—)9—13(-14)-jug., little decrescent at each end of pinnae, the first pair 0.5-0.9 mm distant from pulvinus (paraphyllidia 0), the blades oblong or oblong-elliptic obtuse from shallowly semicordate base, the longer ones (1.3—)1.5—3(—3.3) x 0.6-1 mm, 2-3(-3.3) times as long as wide, the centric midrib sometimes faintly discernible beneath but fully immersed, the blade otherwise glabrous. Peduncles (2-)2.5- 4 cm; capitula without filaments 4-5 mm diam., prior to anthesis moriform; bracts minute caducous; flowers 3-merous 6-androus, the proximal ones a little shorter, the distal ones alone bisexual; calyx membranous 0.4-0.5 mm, its truncate rim either glabrous or with 1-3 minute gland-tipped setulae; corolla turbinate membranous glabrous 2-2.7 mm, the lobes 0.8-1 x 0.75-1 mm, at tip a little thickened but scarcely concave; filaments pink, monadelphous through ±0.5 mm, exserted 5-6.5 mm; ovary minutely glandular. Pods 1-4 per capitulum, linear, straight or nearly so, 25-32 x 3.5-4 mm, 5-8-seeded, at base cuneately contracted into a stipe 1-2.5 mm, apiculate at apex, the coarse, shallowly undulate replum 0.6-0.7 mm wide, the papery valves low-colliculate over each seed, the replum and valves alike finely glandular-setulose but the setulae of the latter in part longer whitish, a little dilated at base and hispid-setiform, the free-falling, individually dehiscent articles elliptic-oblong 4-5.5 mm long; seeds (few seen) basipetal, compressed- obovoid ±3.5 x 2.5 mm, the dull brown testa minutely pitted.
Distribution and Ecology - In sandy or stony campo at 900-1200 m, local near the crests of serras do Cabral and do Espinhaço in lat. 16°30'-18°S in n.-centr. Minas Gerais, Brazil (Cristália; between Francisco Sá and Grão Mogol; e. of Itacambira).—Fl. XI-III.
Mimosa minarum is closely related to M. misera, M. guaranitica and M. brevipinna, but has its own particular leaf-formula, short proper petiole and narrow leaf-outline, and an apparently compact allopatric area of dispersal in campo rupestre on the crest of Sa. do Espinhaço and that of the detached Sa. do Cabral. It is the only member of its group known hitherto from Minas Gerais. The morphological differentiation of this whole series is not strong, and as material accumulates the taxonomic status of its members will need reassessment.
Distribution:Brazil South America
| Minas Gerais Brazil South America