Oenothera capillifolia |
Oenothera albicaulis |
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white-stem evening-primrose, whitest evening primrose, whitish evening primrose |
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Habit | Herbs perennial (short-lived or, sometimes, suffrutescent) or annual, glabrous or strigillose; from a stout taproot. | Herbs winter-annual, densely strigillose, also sparsely villous; from a taproot. | ||||
Stems | 1–many, weakly decumbent to ascending or erect, unbranched to moderately branched, (10–)25–80 cm. |
ascending to decumbent, 1–several from base, sometimes unbranched, erect or ascending, 5–30 cm. |
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Leaves | 1–9 × (0.1–)0.3–1 cm, sometimes fascicles of small leaves to 2 cm present in non-flowering axils; petiole 0–0.6 cm; blade linear to narrowly lanceolate or oblanceolate, often folded lengthwise, usually not much reduced distally, proximalmost leaves sometimes spatulate, base attenuate, margins subentire or serrulate or spinulose-serrate, apex acute. |
in a basal rosette and cauline, 1.5–10 × 0.3–2.5 cm; blade oblanceolate to oblong, margins subentire or coarsely dentate or pinnatifid. |
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Flowers | opening at sunrise; buds with free tips 0–4 mm; floral tube 5–20 mm; sepals 4–12 mm, midribs keeled; petals yellow, fading orangish to purplish, 6–25 mm; antisepalous filaments 2–8 mm, antipetalous filaments 1–4 mm, anthers 2–7 mm, pollen 90–100% fertile; style 9–30 mm, stigma sometimes blue-black, discoid to quadrangular, exserted beyond anthers. |
1–3 opening per day near sunset; buds nodding, weakly quadrangular, without free tips; floral tube 15–30 mm, mouth glabrous; sepals 15–30 mm; petals white, fading pink, usually obcordate, sometimes obovate, (15–)20–35(–40) mm; filaments 11–17 mm, anthers 6–10 mm; style 25–50 mm, stigma exserted beyond anthers at anthesis. |
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Capsules | 10–35 × 1–2 mm, hard, dehiscent 1/2 their length, often tardily dehiscent throughout their length. |
ascending to erect, usually straight, sometimes curved, cylindrical, weakly 4-angled, 20–40 × 3–4 mm, dehiscent 1/2 their length; sessile. |
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Seeds | obovoid, 1–1.8 mm, sharply angled, apex truncate. |
in 2 rows per locule, ellipsoid to subglobose, 0.8–1.5 × 0.5–0.9 mm, surface regularly pitted, pits in longitudinal lines. |
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2n | = 14. |
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Oenothera capillifolia |
Oenothera albicaulis |
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Phenology | Flowering (Feb–)Mar–Jun(–Dec). | |||||
Habitat | Dry, usually sandy flats and slopes. | |||||
Elevation | 1000–2300 m. (3300–7500 ft.) | |||||
Distribution | c United States; sc United States; n Mexico |
AZ; CO; ID; KS; MT; ND; NE; NM; OK; SD; TX; UT; WY; Mexico (Chihuahua, Sonora)
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Discussion | Subspecies 2 (2 in the flora). Oenothera capillifolia is self-incompatible (H. F. Towner 1977). Oenothera berlandieri (Spach) Steudel 1841, not D. Dietrich 1840, is superfluous and cannot be used in Oenothera when transferred from Calylophus, and pertains here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera albicaulis is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). Oenothera albicaulis has been reported from southern Nevada, but documentation is needed of its occurrence there. Anogra pinnatifida Spach, Baumannia pinnatifida Spach, Oenothera pinnatifida Nuttall, O. purshiana Steudel, and O. purshii G. Don are illegitimate names that pertain here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Calylophus | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kleinia | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Meriolix capillifolia | Anogra albicaulis, A. bradburiana, A. buffumii, A. confusa, A. ctenophylla, A. perplexa, O. albicaulis var. xanthosperma, O. ctenophylla, O. sinuata var. bicolor | ||||
Name authority | Scheele: Linnaea 21: 576. (1848) | Pursh: Fl. Amer. Sept. 2: 733. (1813) | ||||
Web links |