Oenothera hartwegii subsp. fendleri
Syst. Bot. Monogr. 83: 212. 2007.
Herbs usually glabrous throughout, sometimes glandular puberulent on distal parts, especially on ovaries. Leaves 1–5 × 0.15–1 cm, fascicles of small leaves to 1 cm (when present); blade linear to oblanceolate or lanceolate, base attenuate to obtuse, rarely nearly clasping, margins entire or subentire, rarely undulate. Flowers: buds with free tips 0.5–3 mm; floral tube 30–50 mm; sepals 9–28 mm; petals 10–30 mm; filaments 5–12 mm, anthers 5–13 mm; style 40–75 mm. 2n = 14.
Phenology: Flowering Apr–Oct.
Habitat: In scattered populations on clay or gravelly soil, sometimes calcareous, in grasslands, often with Juniperus and Prosopis, to woodlands with Juniperus, Pinus edulis, sometimes Pinus ponderosa.
Elevation: 300–2200 m.
Ariz., Kans., N.Mex., Okla., Tex., Mexico (Chihuahua).
Subspecies fendleri is known from Barber, Comanche, and Morton counties, Kansas, south through western Oklahoma and scattered sites in the Texas Panhandle to eastern Chihuahua, central trans-Pecos Texas, central and western New Mexico, and east-central Arizona. It is the most distinctive subspecies in the complex.