Mimosa monticola Dusén
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Authors
Rupert C. Barneby
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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.
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Family
Mimosaceae
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Scientific Name
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Type
365. Mimosa monticola Dusén, Arq. Mus. Nac. Rio de Janeiro 13: 55. 1903.—Typus infra sub var. monticola indicatur.
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Description
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Species Description - Slender, freely branching, diffuse or scrambling microphyllous shrublets 6-10(-?) dm, randomly armed with sharply deflexed infrastipular and sometimes also intemodal aculei 0.5-2 mm, the young stems, lf-stks and peduncles strigose with retrorsely appressed, obliquely basifixed, tapering setae ±1-1.5 mm mixed or not with minute puberulence, the axis of geminate pinnae antrorsely strigose, the firm plane olivaceous subconcolorous, when dry dull brown lfts wholly glabrous or on margin with few weak forwardly appressed cilia, the numerous small globose capitula solitary in the axil of distal lvs on peduncle well surpassing subtending lf-stk. Stipules erect herbaceous, lance- or narrowly ovate-acuminate 2.5-4.3 x 0.7-1.5 mm, striately 5-8-nerved, sometimes weakly ciliolate near base but otherwise glabrous, persistent. Leaf-stalks including livid pulvinus (1 —)2— 15 x 0.2-0.3 mm, progressively shorter upward along branchlets; pinnae 1-jug., the rachis 8-24(-26) mm, the interfoliolar segments 0.5-1.8 mm; lfts of larger lvs (8-) 10-20-jug., abruptly decrescent proximally, less so distally, the first pair 0.4-1 mm distant from ovate acute or lanceolate, 1-nerved paraphyllidia 0.4-1.1 mm, all in outline linear- or narrowly elliptic-oblong from shallowly semicordate or obtusangulate base, abruptly apiculate, those near mid-rachis 2.5-7 x 0.6-1.7 mm, 3.1-4.6 times as long as wide, all smooth veinless above, beneath finely 3-nerved from pulvinule, the straight midrib subcentric beyond mid-blade and weakly 1-2-branched on either side, the adjacent posterior nerve expiring well above mid-blade, the outer posterior one very short. Peduncles subcapillary l-4(-5) cm; capitula without filaments 4-5 mm diam., prior to anthesis moriform; bracts linear or lance-elliptic 0.7-1.3 x 0.1-0.3 mm, glabrous; flowers 4-merous 4-androus glabrous; calyx subobsolete, at most 0.2 mm; corolla submembranous 4-costate, narrowly turbinate or vase-shaped 1.5-2.2 mm, the ovate, shallowly concave lobes 0.6-0.85 x 0.45-0.6 mm; filaments pink, monadelphous through 0.15-0.25 mm below the glabrous ovary, exserted 3.5-5.2 mm. Pods (of var. monticola, and these little known) few per capitulum, subsessile, in profile oblong-elliptic 10-13 x 3.5-4 mm, 2-3-seeded, the replum ±0.45 mm diam., contracted at apex into a cusp less than 1 mm, remotely strigulose with short antrorse setulae, the stiffly papery brown valves glabrous or almost so, colliculate over each seed, when ripe breaking up into free-falling biconvex indehiscent articles 3.5-5 mm long; ripe seeds not seen.
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Discussion
Mimosa monticola is the most northerly-ranging member of ser. Sparsae and the only one of exclusively tropical-montane dispersal. It resembles vicariant, extratropical M. gymnas in most technical characters, especially in recurved aculei, but is a more slender plant, retrostrigulose on stems as well as on peduncles, with striately nerved stipules and substantially smaller leaflets. Two weakly differentiated varieties are discernible.