Canyon or willowherb clarkia

Oenothera epilobioides Nuttall ex Torrey & A. Gray, Fl. N. Amer. 1: 511. 1840; Godetia epilobioides (Nuttall ex Torrey & A. Gray) S. Watson

Stems erect, 20–70 cm, sparsely puberulent. Leaves: petiole to 7 mm; blade linear to nar­rowly lanceolate or oblanceolate, 1.5–2.5 cm. Inflorescences open racemes, sometimes few-branched, axis recurved at tip in bud; buds pendent. Flowers usually cleistogamous; floral tube 1–3 mm; sepals reflexed together to 1 side or in pairs; corolla bowl-shaped, petals fading pink, obovate; stamens 8, unequal, anthers white or cream, outer ones larger than inner. Capsules 10–30 mm; pedicel 5–11 mm. Seeds brown, 0.5–1 mm, scaly, crest inconspicuous. 2n = 18.

Flowering Apr–May. Shady sites, woodlands, chaparral; 0–1000 m; Ariz., Calif.; Mexico (Baja California).

Clarkia epilobioides is known from south-central Arizona in Gila, Maricopa, Pima, and Pinal counties, and widely in west-central and southwestern California and adjacent Baja California, Mexico. In California, it occurs from Contra Costa and San Mateo counties in the San Francisco Bay area to San Diego County in the south, including most of the Channel Islands.

Clarkia epilobioides is modally self-pollinating, and up to half of its flowers do not open, yet set a full complement of seeds (H. Lewis and M. E. Lewis 1955). However, outcrossing does occur, and C. epilobioides is one of the parents of the tetraploid species C. similis, from which it differs by having white, unflecked petals; it is also one of the parents of the tetraploid C. delicata.