Mimosa pteridifolia Benth.

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 pteridifolia Benth.

Type

78. Mimosa pteridifolia Bentham, J. Bot. (Hooker) 4: 391. 1841.-"Brazil, Pohl, Serra Acurua, Blanchet, n. 2850; Prov. Goyaz, Gardner n. 4123.", the data expanded in Martius, Fl. bras. 15(2): 355. 1876: "... prope Capilla de Passé [=Posse], provinciae Goya

Synonyms

Mimosa gemmulata var. adamantina Barneby, Mimosa pteridifolia var. affinis Rizzini, Mimosa pteridifolia var. paucipinnata Rizzini, Mimosa pteridifolia Benth.

Description

Species Description - Unarmed, potentially arborescent shrubs (1-)1.5-3.5 m with stout, densely leafy ascending or arcuately geotropic stems passing upward into a leafless virgate pseudoraceme or panicle of amentiform spikes exserted 1.5-6 dm from expanded foliage, the homotinous branchlets, lf-stks and axes of inflorescence either puberulent or densely pilosulous with incumbent or with stiffer spreading, mostly lutescent hairs to 0.15-0.7 mm intermixed with many sessile spherical golden glands ±0.1 mm diam., the firm, marginally revolute lfts bicolored, brownish and either glabrous or pubescent above, beneath paler, dotted with golden glands but glabrous except for ciliolate midrib. Stipules subulate or linear-lance-attenuate 1.5-7 x 0.3-0.8(-l) mm, sub-persistent. Leafstalks of major lvs 4—14(—16) cm, the petiole including livid pulvinus 4-13 mm, the longer interpinnal segments 4-9 mm, the ventral groove continuous or at times weakly bridged between pairs of pinnae, but spicules 0; pinnae of larger lvs 9-24-jug., strongly decrescent proximally, less or scarcely so distally, the rachis of longer ones 3-6(-7.5) cm, its longer interfoliolar segments 1-2.2 mm; lfts of longer pinnae (22-)25-40-jug., gradually decrescent upward from near or below mid-rachis, the first pair close above the subulate paraphyllidia, the blades oblong, obtuse or emarginate, at base obliquely truncate and bluntly auriculate on proximal side, the longer blades 3-5(-5.5) x (1-) 1.2-2 mm, all dorsally carinate by the slender centric costa, otherwise externally veinless. Spikes 1-3 per node, the axis of longer ones, including short peduncle, 4.5-11 cm; bracts submembranous spatulate or linear-oblanceolate 0.3-1.2 mm, deciduous; flowers 4-merous 8-androus, many functionally staminate; fl-buds obovoid; calyx membranous, shallowly campanulate 0.8-1 mm, the thinly pilosulous ciliolate teeth deltate-triangular 0.2-0.4 mm, separated by broad sinuses; corolla broadly turbinate 1.9-2.2 mm, the ovate acute 1-nerved, pink-purple lobes 0.8-1.3 x 0.8-1.1 mm, at anthesis widely spreading, dorsally pilosulous and gland-sprinkled; filaments pink, free, the longer ones exserted 5-7.5 mm. Pods ascending or spreading, the linear-oblong planocompressed body contracted at base into a stipe ±1.5-2 mm, in profile 25-40 x 4-6 mm, the gently constricted replum ±0.4 mm wide, the replum and valves alike densely yellow-pilosulous and golden-glandular overall, the ripe valves papery, breaking up into 5-7 free-falling oblong articles 4-7 mm long, each at middle colliculate over the seed; ripe seeds not seen.

Distribution and Ecology - In cerrado, cerradão, campo sujo, and at edge of gallery woodland, 800-1250 m, locally common in the central Brazilian Planalto, from Sa. do Roncador in e. Mato Grosso e. to Espigão Mestre in w. Bahia, s. through middle and e. Goiás and Distrito Federal to Sa. dos Cristais, thence weakly e. to centr. Minas Gerais (Várzea da Palma).—Fl. II-VI. Map. 12.

Discussion

Mimosa pteridifolia was the first described member of a group widespread in planaltine Brazil and locally disjunct in Venezuela. The name is here restricted to plants with relatively broad, marginally revolute and consequently dorsally concave leaflets, and with no spicules between pinna-pulvinules. So defined, it is the dominant member of its immediate group in highland Goiás and adjoining Mato Grosso and is known so far from only one station in Minas Gerais, where it is otherwise replaced by M. gemmulata var. gemmulata.

Bentham’s concept of M. pteridifolia included from the first an element of M. gemmulata. As collections have accumulated, the heterogeneous nature of M. pteridifolia sensu Bentham has become more evident, and dispersal patterns of its constituent parts have emerged. The variation has been analyzed in part by Rizzini (1980), who recognized four varieties. One of these is equivalent to M. gemmulata of this account. The var. affinis Rizzini was mistakenly described as aculeate. The holotype of var. paucipinnata shows only some upper leaves which, as often happens, are simpler than primary cauline leaves present in the isotype at NY (pinnae to 12-jug.!).

Distribution

Brazil South America| Bahia Brazil South America| Minas Gerais Brazil South America| Distrito Federal Brazil South America| Mato Grosso Brazil South America| Goiás Brazil South America|