Herbs perennial, clumped; from taproot. Stems ascending to erect, few-branched to well-branched from near base, sometimes branched distally. Inflorescences nodding. Flowers 4-merous, slightly to strongly zygomorphic, opening near sunset; floral tube 3–11(–13) mm; petals white, slightly unequal; filaments with basal scales. Capsules erect, sometimes reflexed in age, fusiform and inconspicuously ribbed, or distal 1/2 pyramidal and abruptly constricted to terete proximal part, weakly or strongly angled in distal 1/2, ribs inconspicuous; sessile. 2n = 14, 28, 42, 56.

Distribution

w North America, n Mexico.

Discussion

Species 2 (2 in the flora).

Subsection Campogaura consists of two species, the diploid (2n = 14) Oenothera boquillensis, which occurs in washes and sandy slopes in dry mountains near the Rio Grande River in Brewster County, Texas, south to central Chihuahua, Coahuila, and Nuevo León, Mexico, and the dipl­oid and polyploid (2n = 14, 28, 42, 56) O. suffrutescens (= Gaura coccinea), which occurs widely in western North America from southern British Columbia to Ontario, Canada, south­ward through the central plains states to the Trans-Volcanic Belt in Oaxaca and Puebla, Mexico.

Selected References

None.

Lower Taxa

Oenothera boquillensis, Oenothera suffrutescens

Key

1	Capsules 5.5–13 mm, fusiform.	Oenothera boquillensis
1	Capsules 4–9 mm, distal 1/2 pyramidal and abruptly constricted to terete proximal part, weakly or strongly angled in distal 1/2.	Oenothera suffrutescens