Mimosa borealis A.Gray
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Authority
Isley, Duane. 1973. Leguminosae of the United States: I. Subfamily. Mimosoideae. Mem. New York Bot. Gard. 25 (1): 1-152.
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Family
Mimosaceae
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Scientific Name
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Description
Species Description - Prickly, usually glabrate, bushy shrub with straight twigs. Leaves clustered (2-3) from spurs and (or) alternate on new growth; pinnae 1-2(-3) pairs; leaflets (3-)4-6 pairs, elliptic to elliptic-oblong, 2-4(-5) mm, glabrous (rarely puberulent). Stipules acicular, inconspicuous. Prickles largely internodal, broad-based, straight to recurved, not paired. Flowers in fragrant, globose, rose to pinkish heads, 9-15 mm diam, 1-2 from spurs, or racemose at branch tips; peduncles slender. Perianth glabrous; calyx broadly campanulate, .4-.8 mm; usually less than half as long as corolla; corolla urceolate, 2-2.5(-3) mm, lobes much longer than tube and conspicuously exceeding calyx. Legume short-stipitate, oblong, curved and (or) contorted, 3-5 cm long, 6-8 mm wide; valves yellowish-brown to brown, membranous, often shiny, prickly or unarmed, usually constricted or twisted between seeds and expressed over the seeds, jointed and ultimately breaking into segments.
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Discussion
M. fragrans Gray Independently of the flower and fruit characters, M. borealis is usually recognized by the heavily armed, straight branches with largely internodal prickles and bright pink flower clusters. Xeric ecotypes of west Texas with reduced number of pinnae and leaflets seem to approach M. zygophylla, but the latter has a nonsegmented legume.
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Distribution
C Texas, w Oklahoma, e New Mexico, to s Kansas and se Colorado. Hills, eroded breaks, disturbed and ruderal areas (e.g., roadsides); with grass, mesquite, oak, junipers; calcareous, rocky soil to red sand. Often abundant in thorn-scrub vegetation. 1300-4100 ft. April-June (July).
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