Oenothera xylocarpa

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.

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