Mimosa ulei

Title

Mimosa ulei

Authors

Rupert C. Barneby

Scientific Name

Mimosa ulei Taub.

Description

264. Mimosa ulei Taubert, Bot. Jahrb. Syst. 21: 432. 1896.—Typus infra sub var. ulei indicatur.

Coarse erect, functionally herbaceous wandlike subshrub from xylopodium, attaining 14-20 dm, the usually single, finely striate purplish-castaneous stem ±6-10 mm diam. at base, bearing 2-5 extremely large long-petiolate lvs at nodes not more than 3 dm from ground-level, thence efoliate and passing upward into a simple pseudoraceme or few-branched panicle of distant subglobose capitula, either glabrous throughout except for minutely puberulent ventral face of pinna-rachises and random gland-tipped or setular trichomes in the inflorescence, or the stems and lf-stks at once puberulent, thinly yellow-setulose and viscidulous, the firm lustrous lfts either glabrous or minutely ciliolate. Stipules at lf-bearing nodes deltate or triangular-acuminate ±615 x 5-10 mm, the firm blades striately many-nerved glabrous lustrous persistent, those at upper efoliate nodes bracteiform, similar in outline, early reflexed or deciduous. Leaf-stalks (15-)20- 56 cm, commonly arched backward, the terete or shallowly grooved petiole (5-)8-33 cm, near middle 1.5-4 mm diam., the longer interpinnal segments 1.5-5 cm; a subulate spicule 1-3.5 mm between each pair of grossly swollen pinna-pulvini; pinnae 4-15(-17)-jug., the often backwardly arched rachis of longer ones (4.5-)7-15.5 cm, the longer interfoliolar segments (1-)1.5-10 mm; lfts of longer pinnae 15-40(-48)-jug., a little decrescent toward each end of rachis, the first pair (0.4-) 1-3.5 mm distant from subulate or lanceolate paraphyllidia 0.6-2.5 mm, the blades narrowly oblong or ovate-oblong obtuse or subapiculate, the larger ones (4-)5-26 x 1.3-9.5 mm, all 5-7-nerved from pulvinule, the slightly displaced midrib and inner primary nerves of ampler blades giving rise to several secondary veinlets, the venulation obtusely prominulous beneath, less so or immersed above. Peduncles 1.5-10 cm; capitula without filaments 10-12.5 mm diam., prior to anthesis either conelike or incipiently moriform; bracts oblance- or obovate-elliptic or spatulate 4-5 x 1-2.5 mm, dorsally shortly stipitate-glandular and sometimes also setulose, the margin either glandular-fimbriolate or ciliolate; flowers 4-merous 8-androus, the lower staminate but hardly smaller; calyx 0.4-1 mm, externally glabrous, the undulate truncate rim either glabrous or ciliolate with a few tiny plain or gland-tipped setulae; corolla narrowly funnelform-campanulate 4.5-6 mm, the deltate-ovate lobes 1.3-1.7 mm, dorsally either smooth, or minutely glandular, or densely setulose, at tip slightly callous, delicately 1-nerved; filaments pink, monadelphous through 0.7-1.3 mm around base of ovary, exserted 10-13 mm. Pods (not seen entire, described from weathered annotinous samples) 1-3 per capitulum, subsessile, in profile broadly oblong-elliptic 35-50 x 10-20 mm, ±6-8(-?)-seeded, at apex contracted into a stout cusp 3-10 mm, the replum 2-2.5 mm wide, the low-convex valves little elevated over seeds, their nigrescent exocarp ±0.4 mm thick in section, traversed by a reticulum of tough fibers, their papery endocarp rufous within, the replum and valves alike setose or glandular-setose overall, the valves when ripe separating entire; seeds not seen.

In a region populated by shrubby and arborescent mimosas of ser. Pachycarpae spectacularly diversified in life-form, M. ulei is itself distinguished primarily by habit: a tall wandlike subshrub with few, exceptionally large, either strictly radical or partly subradical leaves and an effuse, few-branched panicle rising each season about 1.5-2 m from the xylopodium. Although the whole known range of the species spans no more than about 40 kilometers around the southern foothills of Chapada dos Veadeiros, the material presently available falls into two clear-cut series, different in correlated features of pubescence, leaf-formula, and dimensions of leaflets and pods, series described below as varieties. The existence of narrowly vicariant sibling taxa in this part of the Goiás highlands is exemplified in Mimosa by M. oedoclada-M. manidea and M. densa var. densa—var. alligantina of this account, as well as by Chamaecrista conferta var. simulans—var. machrisiana (Irwin & Barneby, 1978: 196, sub Cassia), of which the type-localities almost exactly coincide with those of M. ulei var. ulei and var. grallator respectively.