Mimosa zimapanensis Britton
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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
49. Mimosa zimapanensis Britton & Rose, N. Amer. Fl. 23(3): 166. 1928. M. tenuiflora Bentham, London J. Bot. 5:92.1846, nom. illeg. — "Zimapan in [Hidalgo] Mexico, Coulter."— Holotypus, K (hb. Benth.)!—Non M. tenuiflora Poiret, 1810.
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Synonyms
Mimosa tenuiflora (Willd.) Poir.
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Description
Species Description - Fruticose but of unknown stature, apparently related to M. pringlei but the diagnostic fruit unknown, the annotinous stems densely lenticellate, randomly armed at nodes with 1-2 recurved, brown or stramineous, infrastipular aculei 1.5-2.5 mm, the new growth minutely puberulent and orange-granular but not glandular, the plane lfts facially glabrous, thinly or remotely ciliate, the globose capitula fasciculate by 2-4 in the axils of a succession of small, coevally expanding lvs along new branchlets, forming prior to anthesis a shortly exserted pseudoraceme. Stipules erect, subulate ±1-2 mm, 1-nerved, persistent. Leaf-formula i-ii(-ex Benth. iii)/4-7(-8), the lf-stks of lvs associated with peduncles (the lower not seen) 1-9 mm, the sulcus continuous between pinna-pairs, the rachis of distal pinnae 8-15 mm; lfts oblong-obovate obtuse, mostly 3.5-4.5 x 2-2.5 mm, faintly 1-nerved dorsally, the midrib displaced to divide blade ±1:2. Peduncles ±1-2 cm; capitula without filaments ±7 mm diam., prior to anthesis moriform, the obovoid or claviform receptacle becoming 1-3 mm, the narrowly ellipsoid reddish fl-buds glabrous but at tip strongly papillate; bracts oblanceolate ±0.4 mm, deciduous powers 4-merous 8-androus, glabrous; calyx campanulate 0.6-0.8 mm, the rim minutely denticulate, the teeth 0.1 mm; corolla narrowly vase-shaped ±3.7 mm, the cymbiform lobes ±0.9 x 0.6 mm; filaments free to base (?), exserted 4.5 mm; style filiform; fruit unknown.
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Discussion
I have been unable to associate the type of M. zimapanensis with any modem collection. It resembles M. pringlei var. pringlei in aspect and in fusiform flower-buds, but differs in glabrous flowers. At first sight it suggests M. texana var. filipes, but the aculei are infrastipular, not infrapetiolar. Zimapán, the type-locality of record, is well-known botanically, but has not yielded confirming specimens necessary for interpretation, and the locality may be a mistaken one. In the present state of uncertainty, M. zimapanensis can be associated only provisionally with M. pringlei. Bentham may have seen more complete material in Coulter’s herbarium at Dublin, as the protologue indicates a somewhat higher leaf-formula than shown on the small Kew specimen, which consists of the tip of a flowering branch.