Galpinsia toumeyi Small, Bull. Torrey Bot. Club 25: 317. 1898; Calylophus hartwegii (Bentham) P. H. Raven subsp. toumeyi (Small) Towner & P. H. Raven; C. hartwegii var. toumeyi (Small) Shinners; C. toumeyi (Small) Towner; Oenothera hartwegii Bentham var. toumeyi (Small) Munz

Herbs perennial or sometimes annual, glabrate to strigillose throughout; from a stout taproot. Stems 1–several, ascending to erect, unbranched to densely branched, 15–70 cm. Leaves 1–3.5 × 0.1–0.7 cm, fascicles of small leaves 0.2–2.5 cm present in non-flowering axils; petiole 0 cm; blade narrowly lanceolate, base acute-attenuate, margins entire or obscurely and sparsely serrulate, not undulate, apex acute. Flowers usually 1 per stem opening per day at sunset; buds with free tips 2–9(–12) mm; floral tube (15–)30–60(–70) mm, funnelform in distal 1/2 or less; sepals 10–25 mm; petals yellow, fading pale pink or pale purple, 10–20 mm; filaments 4–12 mm, anthers 6–10 mm, pollen 85–100% fertile; style 35–70(–80) mm, stigma yellow, quadrangular, usually exserted beyond anthers. Capsules 10–50 × 1.5–4 mm, somewhat papery, promptly dehiscent in distal 1/2. Seeds obovoid, 2–3 mm. 2n = 14.

Flowering (May–)Jul–Oct. Local and uncommon on shaded, rocky slopes or disturbed areas, pine-oak forests; 1500–2600 m; Ariz., N.Mex.; Mexico (Chihuahua, Sonora).

Oenothera toumeyi occurs locally from the Chiricahua, Huachuca, and Santa Rita mountains in Cochise and Santa Cruz counties, Arizona, and the Mogollon Mountains in southern Catron County, New Mexico, south through northeastern Sonora in the Sierra Madre Occidental to west-central Chihuahua. H. F. Towner (1977) found that O. toumeyi is self-incompatible and vespertine.