Herbs perennial, acaulescent, densely short-hirsute, also some­times sparsely long-hirsute distally; from a thick, fleshy taproot. Leaves in a basal rosette, 2.6–4.2 (–6.2) × 1.4–4.2 cm; petiole 2.5–9 (–11.5) cm; blade usually oblanceolate to obovate, sometimes suborbiculate, margins dentate, pinnately lobed, lateral lobes oblong to lanceolate, often absent or reduced to only a few lobes toward terminal lobe, base rounded to cordate. Flowers usually 1–3, rarely more, opening per day near sunset; buds erect, quadrangular, without free tips; floral-tube 27–45 (–55) mm; sepals 25–30 mm; petals intensely yellow, fading deep salmon red, obcordate, 25–38 mm; filaments 17–23 mm, anthers 7–10 mm; style 44–65 (–80) mm, stigma somewhat exserted beyond anthers at anthesis. Capsules moderately thin and flexible, lanceoloid, falcate or sigmoid, often contorted and twisted, 4-angled, 35–90 × 7–11 mm, gradually tapering to a long, slender, sterile apex, 10–30 (–40) mm, valves conspicuously wrinkled, dehiscent 2/3–3/4 their length; sessile. Seeds numerous, in 1 row per locule, often forming 2 rows near base of capsule, obovoid, 2.4–3.2 × 1.3–1.7 mm, surface coarsely rugose. 2n = 14.

Phenology: Flowering Jun–Jul(–Aug).
Habitat: Open meadows, flats or slopes on loose granitic gravel, sand, or pumice in Pinus jeffreyi forests with Artemisia tridentata, or in Pinus contorta subsp. murrayana and Abies magnifica forests.
Elevation: 2200–3100 m.

Distribution

• Generated Map
• Legacy Map

Calif., Nev.

Discussion

Oenothera xylocarpa is known from three disjunct areas in California and adjacent Nevada: Mount Rose, Washoe County, Nevada; southern Sierra Nevada, southwestern Mono County, California, from the vicinity of Crestview south to Casa Diablo; and the area in the southern Sierra Nevada bounded by Horse­shoe and Big Whitney meadows to the east and north, and Casa Vieja and Volcano Meadows to the south and west, west-central Inyo and eastern Tulare counties, California.

Selected References

None.

Lower Taxa

None.