Mimosa emoryana
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Title
Mimosa emoryana
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Author(s)
Rupert C. Barneby
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Scientific Name
Mimosa emoryana Benth.
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Description
54. Mimosa emoryana Bentham, Trans. Linn. Soc. London 30: 426. 1875.—Typus infra sub. var. emoryana indicatur.
Stiffly branched microphyllous shrubs attaining 12 dm, armed below almost every node with one infrapetiolar and sometimes in addition 1-2 infrastipular, broad-based recurved, at first brown-tipped but later blanched aculei (2-)3-9 mm, the infrapetiolar one often so far displaced as to appear opposed to the antecedent lf, the young branches, lvs and fls silky-puberulent or subvelutinous throughout, the globose or ellipsoid capitula arising either directly from the axil of coeval lvs on long-shoots or from small brachyblasts on older wood. Stipules subulate or linear-attenuate 1-3.5 mm, weakly 1-nerved or externally nerveless. Leaf-formula i-iv(-v)/3-6 (-7), the lf-stks 2-40 mm, the ventral sulcus obscure or continuous (spicules 0); rachis of longer pinnae 2-12 mm; lfts oblong or elliptic-oblong, obtuse or subacute, the longer ones (2.5-)3-5.5 x 1-2 mm, 2.1-2.8 times as long as wide, all externally veinless or faintly 2-nerved dorsally, the midrib subcentric. Peduncles 6-24 mm; capitula without filaments 6-10 x 5.5-7 mm, prior to anthesis moriform, the pyriform fl-buds silky-puberulent, the receptacle 1-8 mm long; flowers 5-merous 10-androus, all bisexual, puberulent overall; calyx membranous, campanulate or turbinate-campanulate (0.6-)0.8-1.4 mm, the depressed-deltate teeth 0.1-0.3 mm; corolla vaseshaped 3-3.9 mm, the triangular-acuminate, slightly flaring lobes 1-1.4 mm; filaments pink, monadelphous through 0.1-0.3 mm, exserted 4.5-5.5 mm; ovary puberulent-tomentulose. Pods 1-7 per capitulum, sessile or almost so, in profile linear 20-50 x 5-6.5 mm, arched downward or somewhat twisted, 3-6(-7)-seeded, the scarcely constricted replum and papery valves alike densely puberulent overall with short erect hairs and the valves always, the replum commonly, hispid with erect glabrous or scaberulous setae to 1-2.5 mm, the valves bullately distended over each seed, breaking up into free-falling, individually dehiscent articles 5-9 mm long.
Mimosa emoryana consists of two intergradient but, it seems, geographically separated varieties. The var. chihuahuana resembles M. monancistra in ellipsoid capitula, but typical M. emoryana in downwardly displaced infrapetiolar aculei. Only the extended primary leaf-axis and axis of receptacle distinguish var. chihuahuana from var. emoryana, and the variation is almost continuous.