Monographs Details: Mimosa spixiana 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 spixiana Barneby
Synonyms:Mimosa sericantha Benth., Mimosa interrupta Benth.
Description:Species Description - Presumably shrubby or arborescent like related species but stature not recorded, the smooth livid homotinous branchlets and nigrescent foliage glabrous except for minute sessile yellow glands scattered along lf-stks and over dorsal face of relatively ample firm venulose sublustrous concolorous lfts, the amentiform fl-spikes geminate in the axil of coevally expanding lvs, the fls glabrous gland-sprinkled. Stipules stiffly erect, narrowly lance-acuminate 4-8 x 0.4-1.3 mm, 1-nerved, persistent. Leaf-stalks stout 4-6 cm, the petiole including pulvinus 3-8 x 1.2-1.5 mm, the interpinnal segments 7-11 mm, the open ventral sulcus bridged between pairs of pinnae and the bridge between lowest pair surmounted by a spicule; pinnae 4-5-jug., distally accrescent, the axis of distal pair 4-5 cm, the interfoliolar segments 3-5 mm; lfts of longer pinnae 10-14- jug., subdecrescent proximally but otherwise subequilong, the first pair 1.2-1.5 mm distant from lance-subulate paraphyllidia 0.8-1.4 mm, all in outline obliquely oblong or ovate-oblong from semicordate base, deltately acute at apex, those at and above mid-rachis 7-12.5 x 3-4.3 mm, ±3-3.5 times as long as wide, the blades smooth veinless above, beneath prominently 4-nerved from pulvinule, the stout tapering costa displaced to divide blade ± 1:3-3.5, its posterior neighbor nearly as strong and produced well beyond mid-blade, like the costa several-branched, the outer nerves weak and short. Peduncles ±3 cm; axis of spikes 4-5.5(-?) cm; bracts linear-oblanceolate 1.4-1.7 mm, deciduous; flowers sessile, 4-merous 8-androus, the sparsely gland-dotted buds narrowly obovoid; calyx campanulate 1.2 mm, the triangular teeth ±0.35 mm; corolla narrowly turbinate 2.8 mm, the lobes ±1.3 x 0.7 mm, charged externally with a few golden glands; filaments of unknown color, free to base, exserted ±4.5 mm; ovary glabrous; fruit unknown.

Distribution and Ecology - In unrecorded habitat but to be expected in cerrado near or above 700 m, known only from the type-locality near the source of rio Carinhanha, near 15°S in extreme n.-w. Minas Gerais, Brazil.-Fl. IX-X(-?).

Discussion:

The type of M. spixiana was misidentified by Bentham as M. interrupta; it is clearly different, however, in absence of pilosulous indumentum, elongate stipules, low leaf-formula (as given in Latin diagnosis) and corolla thinly gland-sprinkled but not resinous. The leaflet-venation suggests affinity to M. sericantha, but in this case a higher leaf-formula with proportionately smaller leaflets coinciding with flowers only thinly glandular but not gray-pilosulous are decisively different. The fruit, when discovered, will perhaps provide stronger clues to its affinities.

The species is named in honor of the Bavarian zoologist Johann Baptist von Spix, Martius’s companion in Brazil in the years 1817-1820 and co-author with Martius of the magnificent Reise Brasilien.

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

Narratives:Mimosa spixiana