Herbs annual, villous proxi­mally, sparsely villous along veins and on margins, usually glabrate, sometimes strigillose distally; from taproot. Stems ascending, usually well-branched from base and distally, rarely unbranched, 15–60 cm. Leaves in a basal rosette and cauline, 1.5–8 × 0.2–0.6 (–1.5) cm, blade very narrowly elliptic to oblanceolate or oblongelliptic, margins entire or weakly sinuate-dentate. Flowers 3 (or 4) -merous, zygomorphic, open­ing at sunset; floral-tube 4–5.5 mm; sepals 4.5–6 mm; petals white, fading pink, elliptic-obovate, 3.5–5 mm; filaments 2–3.5 mm, anthers 1.5–3 mm, pollen 35–65% fertile; style 9–10 mm, stigma surrounded by anthers. Capsules narrowly obovoid, 3 (or 4) -winged, furrowed between wings, 7–9 × 3–5 mm, narrowed at base; sessile. Seeds (1 or) 2–5, yellowishto light-brown, 1.5–3.5 × 1–1.5 mm. 2n = 14.

Phenology: Flowering Apr–Jul.
Habitat: Open, sandy sites.
Elevation: 200–600 m.

Distribution

• Generated Map
• Legacy Map

Okla., Tex.

Discussion

Oenothera triangulata is a PTH species and forms a ring of 14 chromosomes in meiosis. The species is self-compatible and autogamous (P. H. Raven and D. P. Gregory 1972[1973]). It may have been derived from hybridization between O. patriciae and O. suffulta. The species has a relatively narrow distribution across south-central Oklahoma and north-central Texas (Oklahoma in Cleveland, Comanche, Cotton, Grady, Oklahoma, Rogers, Stephens, and Tulsa counties; Texas in Archer, Baylor, Callahan, Clay, Coleman, Crosby, Eastland, Erath, Jones, Montague, Taylor, Throckmorton, Tom Greene, Wichita, Wilbarger, and Young counties).

Selected References

None.

Lower Taxa

None.