27. Oxalis metcalfei (Small) R. Knuth, Notizbl. Bot. Gart. Berlin-Dahlem. 7: 314. 1919.
Metcalfe’s wood-sorrel Metcalfe’s wood-sorrel
Ionoxalis metcalfei Small in N. L. Britton et al., N. Amer. Fl. 25: 39. 1907; I. monticola Small; Oxalis bulbosa A. Nelson; O. neomexicana R. Knuth
Herbs perennial, acaulous, rhizomes and stolons absent, bulb <5–10 mm>, usually surrounded by dense cluster of bulblets, <3–4 mm> (sometimes obscuring bulb); bulb scales 3-nerved. Leaves basal; petiole 7–15 cm; leaflets 3, green, obtriangular-obcordate, 11–25 mm, lobed 1/6–1/3 length, <lobes apically rounded to shallowly convex>, surfaces glabrous, oxalate deposits usually in narrow band <0.5–1.5 mm> along margins at base of notch, sometimes evident on one surface but not other, rarely absent. Inflorescences umbelliform cymes, 3–7-flowered; scapes 7–22 cm, glabrous. Flowers tristylous and distylous; sepal apices with 2 orange, <narrow-elongate, nonconfluent> tubercles; petals white to pale green proximally with green veins, purplish to lavender or pink distally, (9–)12–16 mm. Capsules cylindric, 6 mm, glabrous. 2n = 28, 42.
Flowering (Jun–)Jul–Sep(–Oct). Stream banks, wet meadows, canyon bottoms, talus, rocky banks, crevices, juniper-chaparral, Cercocarpus, pine, yellow pine-Douglas fir-oak, Douglas fir-aspen, pine-white fir-Douglas fir, spruce-fir, or spruce woodlands; 1800–3100(–3400) m; Ariz., Colo., N.Mex., Tex.; Mexico (Chihuahua, Durango, Sonora, Zacatecas).
Oxalis metcalfei has mostly been identified as O. alpina (Rose) Rose ex R. Knuth, but the latter is a species of south-central Mexico, far from the populations in northwestern Mexico and the southwestern United States. Oxalis alpina has leaflets with dotlike oxalate deposits scattered throughout the lamina, concentrated near margins, or as continuous, filiform marginal bands around the lobe apices; the corollas usually are white. Oxalis metcalfei is consistently different in the nature of its foliar oxalate deposits and the corollas usually are purplish to lavender or pink.
Plants with chromosome numbers of 2n = 28 are found in both Arizona and New Mexico; those with 2n = 42 are found only in New Mexico (S. C. Weller and M. F. Denton 1976).