Mimosa alleniana

Title

Mimosa alleniana

Author(s)

Rupert C. Barneby

Scientific Name

Mimosa alleniana Morong

Description

331.  Mimosa alleniana Morong, Ann. New York Acad. Sci. 7: 98. 1893.—"[Paraguay:] railroad track between Escota and Caballero ([Morong] 1501)."—Holotypus, a fragmentary unicate collected 20.1 (fr), NY!

M. hirsutissima var. pseudodistans Chodat & Hassler, Bull. Herb. Boissier II, 4: 488 (=P1. hassler. 402). 1904.—"Paraguay: ... in campo pr. San Estanislao . . . [Hassler] n. 4327;. . . pr. Vaqueria Capibari. . . n. 4395; in campo Ipe hu, Sierra de Maracayu . .. n. 4948; . . . pr. Chololo ... n. 6787; ... pr. Valenzuela, .. . n. 6989 ad formam erectam transiens."— Syntypi omnes, G!; isosyntypi, 4395, K! NY! W!- M. hirsutissima var. pseudodistans fma decumbens Chodat & Hassler, l.c., nom. superfluum.

M. hirsutissima var. pseudodistans fma erecta Chodat & Hassler, op. cit.: 489 (403). 1904.—"[Paraguay:] ... in campo pr. flumen Tapiraguay . .. [Hassler] n. 4308; .. . pr. Igatimi... n. 5553; ... pr. Bellavista (Apa). .. n. 8398."—Syntypi omnes, G!; isosyntypi, 5553, K! NY! W!

M. acerba sensu Chodat & Hassler, op. cit.: 551 (407), ex parte (6818, G! NY!); non Bentham.

Small slender unarmed, functionally herbaceous subshrub (0.5-)l-4, perhaps to 6 dm, the few simple or distally few-branched stems 0.8—1.4 mm diam. at base, diffuse or incurved-ascending from woody rootstock or xylopodium to 1.5 cm diam., the stems, lf-stks and peduncles at once minutely puberulent and softly pilose with fine spreading-ascending flexuous setae to 1.5-3 mm, the foliage pale-olivaceous subcon-colorous, the lfts thinly silky-strigulose on both faces, not or indistinctly and very narrowly pallid-marginate, on dorsal face coarsely pallid-venose, the small globose or plumply ellipsoid capitula axillary to coevally expanding lvs, early becoming lateral and surpassed by associated lf. Stipules erect subherbaceous, narrowly lanceolate or lance-oblong (2.5-) 3.5-7 x (0.5-)0.6-1.3 mm, weakly several-nerved, persistent. Petioles 5-18 mm, at middle 0.4-0.6 mm diam., the ventral groove broad and shallow, bearing at apex an interpinnal spicule 0.6-2 mm; pinnae 1-jug., progressively longer upward along stem, the members of some pairs often of different lengths, the rachis of those near and beyond mid-stem (2-)2.5-6.5(-7.5) cm, the longer interfoliolar segments 1.5—2.5(—3) mm; lfts of pinnae near midstem upward (15-)20-29-jug., very gradually decrescent upward from below mid-rachis, the small first pair 0.4-1.6 mm from linear-subulate paraphyllidia 0.6-2 mm, the blades narrowly oblong or obliquely elliptic-oblong from semicordate base, acute or abruptly deltate-apiculate, the larger ones of a plant (4-)5-8.5 x (1.2-) 1.5-2.5 mm, 3-3.9(—4.4) times as long as wide, all veinless above, beneath (2-)3-nerved from pulvinule, the midrib thick and pallid its whole length or sometimes only beyond middle, displaced to divide blade 1:2-3, from near middle upward pinnately (3-)4-6-branched on each side, the secondary venules coarsely V-forked within the margin, the inner posterior nerve produced to or beyond midblade, there anastomosing with a secondary nerve from midrib, the outer primary very short or obsolete. Peduncles either solitary or geminate, slender or subcapillary 7-22 mm; capitula without filaments 4-6(-6.5) mm diam., prior to anthesis moriform, the obovoid fl-buds not concealed by bracts but often surpassed by emergent bracteal setae; bracts linear 1.6-2.3 mm, glabrous 1-nerved dorsally, distally ciliate with ascending setae to 0.6-1.3 mm; flowers 4-merous 4-androus, some lower ones small and staminate; calyx including cilia 0.4-1 mm, the membranous tube 0.2-0.4 mm, its rim with fine cilia 0.2-0.6 mm, some of these occasionally subconnate at base, sometimes all subobsolete; corolla narrowly turbinate or funnelform 2.1-2.5 mm, the membranous ovate, shallowly concave lobes 0.8-1 x 0.5-0.75 mm, finely minutely puberulent dorsally; filaments pink, free to base or almost so, exserted 4.5-8 mm. Pods (few seen) ±2-10 per capitulum, subsessile, in profile undulately narrow-oblong 10-17 x 3-3.5 mm, 3-5-seeded, the replum 0.2-0.3 mm wide, like the thin greenish-stramineous valves hispid overall with slender ascending, microscopically scaberulous setae to ±0.7-1.2 mm, the biconvex, free-falling articles 2.5-3 mm long; seeds (few seen) lentiform ±2.5 x 2 mm, the testa smooth brown.

In campo or campo cerrado, and in disturbed brush-woodland, ±250-600 m, of apparently bicentric range: locally common and widespread in Paraguay e. of río Paraguai and in adj. s.-w. Mato Grosso do Sul; local between 22° and 23°S in e.-centr. S. Paulo (Mogi-guaçu; Ityrapina; Botucatú).—Fl. IX-ll.—Dormideira(S. Paulo); eaten by livestock in Mato Grosso do Sul.

Among the all too numerous unarmed genuine mimosas with conjugate pinnae and poorly developed calyx that pullulate in campestrian Paraguay M. alleniana is easily recognized by the coarse pallid venation of the dorsal face of leaflets, and by this feature alone can be distinguished from unarmed forms of M. brevipetiolata. The leaflet venation is similar in pattern, although more emphatic, to that seen in M. pedunculosa and M. leimonias, but the first of these differs in its peculiar stature, having peduncles nearly as long as the primary cauline axis, the second has on the average smaller capitula, and both have glabrate, not softly pilose, stems and leaf-stalks. The species was named in commemoration of Dr. Timothy Field Allen (1837-1902), an eminent homeopathic physician in New York City, founding member and for many years vicepresident of the Torrey Botanical Club, and student of Characeae, who contributed to the expenses of thornas Morong’s travel in Paraguay in 1888-1890.