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Oenothera xylocarpa

Distribution: Mount Rose, Washoe Co., Nevada, southern Sierra Nevada, southwestern Mono Co., California, from the vicinity of Crestview south to Casa Diablo, and 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 cos., California.

Habit: Acaulescent perennial herb from a thick fleshy taproot, rosette simple.

Leaves: Leaves 2.6-4.2 (-6.2) cm long, 1.4-4.2 cm wide, usually oblanceolate to obovate in outline, occasionally suborbicular, canescent with short erect to curved and somewhat appressed hairs, 0.2-0.3 mm long, usually with reddish purple spots scattered over the surface, the margin dentate, pinnately lobed, lateral lobes oblong to lanceolate, often absent or reduced to only a few lobes toward the terminal lobe, the base rounded to cordate, abruptly tapering to the petiole 2.5-9 (-11.5) cm long.

Flowers: Flowers 1 to 3 or rarely more per day opening near sunset, with a strong sweet fragrance, ovary 12-18 mm long, curved at the base, densely short-hirsute, pedicel ca. 1 mm long, floral tube 27-45(-55) mm long, flaring to 4-5 mm at the mouth, densely short-hirsute and also sometimes sparsely long-hirsute, glabrous within, sepals 25-30 mm long, 3.5-5 mm, separate and reflexed at anthesis, occasionally reflexed in pairs, infused with deep red often very intensely, moderately to densely short-hirsute, petals 25-38 mm long, 30-40 mm wide, intensely yellow, fading deep salmon red, broadly obcordate, the notch shallow, staminal filaments 17-23 mm long, yellow, anthers 7-10 mm long, yellow, style 44-65(-80) mm long, stigma lobes 3-4 mm long, somewhat elevated above the anthers at anthesis.

Fruit: Capsule dehiscent, 35-90 mm long, 7-11 mm in diameter, lanceoloid, falcate, the surface conspicuously wrinkled, often contorted and twisted, flexible at maturity, quadrangular in cross-section, tapering to a conspicuous sterile apex 10-30(-40) mm long, strongly asymmetrical at the base, dehiscing 2/3-3/4 the length of the capsule.

Seeds: Seeds in 1 row per locule, 2.4-3.2 mm long, 1.3-1.7 mm in diameter, often forming 2 rows near the base of the capsule, obovoid, often truncate at the apex, coarsely rugose, the surface with turgid and collapsed papillae, the raphial face with two small longitudinal ridges nearly the length of the seed, dark purplish brown appearing nearly black.

Chromosomes: Gametic chromosome number: n = 7.

Notes: FNA, Self-compatible, but modally outcrossing.


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