Monographs Details: Mimosa parviceps 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 pogocephala Benth., Mimosa setistipula Benth.
Description:Species Description - Unarmed arborescent shrubs attaining 3 m, with virgately erect, few-forked homotinous branches at once puberulent and hispid like lf-axes with stiff but slender, narrowly ascending setae to ± 1 mm, nowhere lanate, the subconcolorous dull brown-olivaceous lfts either finely minutely gray-puberulent overall or the distal ones facially glabrous, all discontinuously setose-ciliate, the small globose capitula solitary or seldom geminate in axil of contemporary or immediately hysteranthous lvs near apex of growing branchlets, soon surpassed by leafy axis, the pods lateral and immersed in foliage. Stipules firm lanceolate 4-5 x 0.6-1 mm, pubescent dorsally like adjacent stem, persistent after fall of associated lf. Leaf-stalks including firm pulvinus 2-5 x 0.6-1 mm, shallowly grooved ventrally; pinnae 1-jug., their axis 3-6(-6.5) cm, the longer interpinnal segments 2.5-4.5 mm, shallowly excavate laterally between successive lfts; lfts 10-13-jug., little graduated, the unequal first pair 2-3 mm distant from usually small subulate, rarely dilated and foliolar paraphyllidia, the thin-textured blades narrowly oblong-elliptic from semicordate base, obtuse-apiculate or deltately acute, the longer ones 9.5-14.5 x 2.5-4.5(-4.7) mm, 2.8-3.8 times as long as wide, 4(-5)-nerved from pulvinule, the veins immersed above, weakly prominulous beneath, the simple or obscurely few-branched midrib dividing the blade 1:1.3-2, the inner posterior nerve produced beyond mid-blade, the rest shorter. Peduncles (15-)20- 35 mm; capitula without filaments 5-6 mm diam., prior to anthesis moriform, the obovoid 4-keeled fl-buds densely gray-puberulent above middle; bracts narrowly oblanceolate ±1.5 mm, either puberulent or glabrate dorsally, weakly setose-ciliate; flowers 4-merous 4-androus, many proximal ones functionally staminate; calyx membranous, shallowly campanulate 0.2-0.3 mm, the angulate rim microscopically ciliolate; corolla narrowly funnelform 2.2-2.7 mm, the concave, scarcely callous lobes 0.8-1 x 0.5-0.6 mm; filaments pink, free to base, exserted 7-8 mm. Pods (1—)2—5 per capitulum, sessile, in profile narrowly oblong-elliptic (12-) 18-25 x 5-6 mm, 3.5-5 times as long as wide, (2-)3-4-seeded, the replum 0.9-1.1 mm wide, the stiffly papery, ultimately crustaceous and brittle valves at once puberulent and pilose with slender ascending setae to 1.5 mm, when ripe separating from replum and from each other but only tardily falling, after discharge of seeds erratically breaking up into articles 5-5.5 mm long, the endocarp septiferous as in M. pogocephala; seeds not seen.
Distribution and Ecology - In cerrado, on brown sandy soils associated with sandstone outcrops at ±1000 m, known only from upper e. slopes of Sa. do Espinhaço at points 13-18 km e. of Diamantina, near 18°20'S in centr. Minas Gerais, Brazil; possibly also (Glaziou 19126, lacking field-label and perhaps mislabelled, K! P!) at Tripuhy near Ouro Preto at ±20°25'S.—Fl. III-IV(-?); fr. of past season persistent into II.
Mimosa parviceps is closely akin to M. pogocephala, but apparently different in greater stature, persistent stipules, fewer (10-13, not 12-23) pairs of leaflets in longer pinnae, longer peduncles but smaller capitula, and particularly in the longer, proportionately narrower pod pilose with ascending, minutely scaberulous setae, not coarsely hispid with stout, bulbous-based smooth ones. The also closely related M. montis-carasae has deciduous stipules, somewhat thicker capitula, and pod thinly hispid with vertically erect setae. It is found at greater elevations (1500-1900 m) and at points distant about two degrees of latitude southward along Serra do Espinhaço.
A peculiar specimen from close to the type-locality of M. parviceps and very similar to it in most characters (CFCR 2216, NY) cannot at present be classified with assurance. It differs from typical M. parviceps in bearing a few small scattered prickles on the stems (unknown in most other Pogocephalae) and in different pubescence of the seemingly more readily articulate pod. It may represent M. parviceps introgressed by some aculeate species, but requires field-observation.
Distribution:Brazil South America
| Minas Gerais Brazil South America