Mimosa pseudosepiaria Harms

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 pseudosepiaria Harms

Type

90. Mimosa pseudosepiaria Harms, Bot. Jahrb. Syst. 42: 207. 1908.—"Bahia: Sumpfige Niederungen bei Remanso (ULE n. 7383—Jan. 1907)."—Holotypus, +B = FNeg. 1428!; clastotypus (fragm), F!; isotypi, G! HAMB! K!

Description

Species Description - Microphyllidious bushy treelets 3-4 m, randomly armed below some nodes with solitary stout recurved broad-based infrapetiolar aculei to ±5-8 mm, the annotinous branchlets livid-brown, densely pallid-lenticellate, the young stems, lf-stks and peduncles minutely villosulous with fine hairs not over 0.1 mm mixed with scattered livid granules, the thin-textured olivaceous subconcolorous lfts either glabrous on both faces or subappressed-puberulent dorsally, the inflorescence a succession of small few-fld globose capitula axillary to and shorter than lvs going out into a leafless, simple or few-branched pseudoraceme exserted not more than 5-15 cm from foliage. Stipules linear-subulate 1.5-3 x 0.2-0.3 mm, puberulent dorsally, tardily deciduous. Leafstalks (1.5—)2—5 cm, the petiole including livid pulvinus 3-10 mm, at middle 0.4-0.6 mm diam., the longer interpinnal segments 3.5—8(—11) mm, the ventral groove narrow, bridged between pinna-pairs, minutely spiculate or not; pinnae (4-)5-9-jug., a little decrescent at proximal or at both ends of lf-stk, the rachis of longer ones (12—) 15— 25 mm, the interfoliolar segments up to 0.6-1.1 mm; lfts of longer pinnae 15-23-jug., slightly decrescent at both ends of rachis, the first pair 0.4-0.8 mm distant from small erect paraphyllidia, all in outline linear obtuse or subacute, the longer ones 2.3-7.5 x 0.5-1.5 mm, ±4-6.5 times as long as wide, the posterior angle rounded at base, the filiform simple subcentric costa discolored beneath but not prominulous, the upper face veinless. Peduncles solitary or geminate very slender (3—)5—16 mm; capitula without filaments 4-5 mm diam., prior to anthesis moriform, the floral axis not over 2 mm, the plumply obovoid fl-buds thinly minutely puberulent distally; flowers mostly 4(-5)-merous and bisexual, in some capitula some lower ones staminate 3-merous, all diplostemonous; calyx membranous campanulate 0.45-0.7 mm, externally glabrous or microscopically puberulent, the broadly low-toothed rim minutely puberulent; corolla 1.9-2.7 mm, narrowly funnel-form, the ovate acute membranous 1-nerved lobes 1-1.2 x 0.6-0.8 mm; filaments white, free to base, exserted ±3.5-4 mm; ovary shortly stipitate pilosulous. Pods (Lewis, 1987, fig. 8R) stipitate, the slender stipe (4-6.5 mm, the linear-oblong planocompressed body 40-60 x 4.5-6 mm, cuneate or attenuate at either end, the shallowly undulate, ephemerally puberulent replum 0.4-0.5 mm wide, the papery brownish sublustrous valves delicately venulose and minutely livid-granular, when ripe breaking up into (6-)7-9 free-falling articles ±4.5-6 mm long; ripe seeds not seen.

Distribution and Ecology - In caatinga thickets at low elevations, known only from the lower S. Francisco valley near 9°S in w. Pernambuco and adj. Bahia.—Fl. I-V.

Discussion

Mimosa pseudosepiaria, first collected near Joàzeiro by Martius in 1819 but not described until long afterward, is a critical entity, closely akin to Mm. bimucronata, hexandra and exalbescens, all of which are known to occur in lowland Bahia, and especially to M. hexandra, which has been collected with it around Remanso and Petrolina. It differs from M. bimucronata in the reduced foliage with fewer, simply costate and on the average smaller leaflets; from M. exalbescens by much narrower pods (4.5-6, not 810 mm wide); from M. hexandra primarily in thin-textured craspedium; and from the two last collectively in mostly tetramerous, not trimerous flowers. However, in all members of the group some intraspecific variation in number of flower parts has been observed, and I am perhaps overweighting the character in this context. It seems certain, however, that the bisexual flowers of M. bimucronata and M. pseudosepiaria are regularly tetramerous and only some smaller staminate ones trimerous, whereas all are trimerous in M. hexandra and M. exalbescens.

Distribution

Brazil South America| Bahia Brazil South America| Pernambuco Brazil South America|