Western yellow wood-sorrel Western yellow wood-sorrel

Oxalis californica (Abrams) R. Knuth var. subglabra Wiegand; O. corniculata Linnaeus subsp. albicans (Kunth) Lourteig; O. corniculata var. wrightii (A. Gray) B. L. Turner; O. pilosa Nuttall var. wrightii (A. Gray) Wiegand; O. wrightii A. Gray; Xanthoxalis albicans (Kunth) Small; X. wrightii (A. Gray) Abrams

Herbs perennial, caulescent, rhizomes and stolons absent, bulbs absent. Aerial stems usually 2–8 from base, usually decumbent to prostrate, less commonly ascending, <sporadically rooting at nodes>, 10–40 cm, becoming woody proximally, puberulent to hirtellous-puberulent, <hairs usually antrorsely curved or crisped, sometimes ± straight, nonseptate, longer hairs 0.2–0.3(–0.8) mm>. Leaves basal and cauline; stipules rudimentary or oblong, margins narrowly flanged, apical auricles absent; petiole (1–)3–7(–10) cm, <hairs nonseptate>; leaflets 3, glaucous and gray-green to yellowish green, obcordate, 5–10(–15) mm, lobed 1/5–1/3 length, surfaces glabrous to loosely strigose, oxalate deposits absent. Inflorescences umbelliform cymes, 1–2(–3)-flowered; peduncles 1.5–5 cm. Flowers semihomostylous, <within level of leaves>; sepal apices without tubercles, <surfaces strigose to hirsute-strigose>; petals yellow, rarely with red lines proximally, 6–10(–12) mm. Capsules angular-cylindric, abruptly tapering to apex, 14–20 mm, strigose-hirsute. <Seeds brown to blackish brown, transverse ridges rarely with whitish lines or spots>.

Flowering Apr–Aug(–Oct). Desert scrub, grasslands, mesquite-acacia, pinyon-juniper, oak-pine-juniper, oak-buckthorn, riparian woodlands (sycamore-hackberry-walnut-ash-willow), stream banks, meadows, washes, hillsides, ravines, canyons, disturbed sites; (600–)700–1900(–2100) m; Ariz., N.Mex., Tex.; Mexico; Central America (Guatemala).