Oenothera cespitosa |
Oenothera engelmannii |
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fragrant evening-primrose, tuft evening-primrose |
Engelmann's evening-primrose |
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Habit | Herbs perennial, acaulescent or caulescent, usually hirsute or villous, usually also glandular puberulent, or exclusively strigillose, rarely glabrous; from stout taproot, sometimes lateral roots producing adventitious shoots. | Herbs winter-annual, conspicuously villous throughout, also strigillose on leaves and distal parts; from a taproot. | ||||||||||||||||||||||||||||
Stems | (when present), usually ascending or decumbent, unbranched or branched from near base, 0–40 cm. |
erect, unbranched or with few, spreading branches, 30–50(–80) cm. |
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Leaves | 1.7–26(–36) × (0.3–)0.5–4.5(–6.5) cm; petiole (0.2–)1.7–11(–14) cm; blade usually oblanceolate to rhombic or spatulate, rarely elliptic, obovate, lanceolate, or linear-oblanceolate, margins irregularly sinuate-dentate, serrate, pinnatifid, lobed, or subentire, apex usually acute to rounded, rarely acuminate. |
in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, (1–)2–6(–8) × 1–2(–3) cm; sessile; blade lanceolate to oblong lanceolate, proximal ones sometimes oblanceolate, margins coarsely repand-dentate or -pinnatifid. |
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Flowers | 1–4(–6) per stem opening per day near sunset, with moderate to strong sweet scent with a rubbery background scent; buds usually erect, rarely recurved (during early development); floral tube (20–)40–140(–165) mm; sepals (15–)18–45(–54) mm; petals white, fading rose or rose pink to dark or deep rose purple, or pink to pale or light rose, or lavender, obovate or obcordate, (16–)20–50(–60) mm; filaments (6–)10–30(–35) mm, anthers (6–)9–17(–20) mm; style (45–)60–180(–185) mm, stigma exserted beyond anthers at anthesis. |
1–several opening per day near sunset; buds nodding, weakly quadrangular, without free tips; floral tube 20–30 mm; sepals 13–21 mm, not spotted or with scattered small, maroon spots; petals white, fading pink, broadly obovate or obcordate, 15–30 mm; filaments 14–16 mm, anthers 6–8 mm; style 40–50 mm, stigma exserted beyond anthers at anthesis. |
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Capsules | straight, curved, falcate, or sigmoid, usually cylindrical to lanceoloid or ellipsoid, sometimes ovoid, usually obtusely 4-angled, (10–)13–50(–68) × 4–9 mm, tapering to a sterile beak 6–8 mm, valve margins with rows of distinct tubercles to sinuate or nearly smooth ridges, dehiscent 1/3–7/8 their length; pedicel (0–)1–40(–55) mm. |
widely spreading, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering gradually from base to apex, 30–60 × 2–3 mm; sessile. |
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Seeds | numerous in 1 or 2 rows per locule, usually obovoid, oblong, or triangular, rarely suborbicular, 2.1–3.9 × 1–2.6 mm, embryo 1/5–2/3 of seed volume, surface papillose, reticulate or rarely irregularly roughened; seed collar sealed by a thin membrane, this flat or depressed into raphial cavity, when depressed often splitting, becoming separated from seed collar. |
numerous, in 1 row per locule, brown, narrowly obovoid, 1–1.5 mm. |
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2n | = 14, 28. |
= 14. |
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Oenothera cespitosa |
Oenothera engelmannii |
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Phenology | Flowering Apr–Aug(–Sep). | |||||||||||||||||||||||||||||
Habitat | Sandy prairies, dunes, disturbed areas, roadsides. | |||||||||||||||||||||||||||||
Elevation | 500–1300 m. (1600–4300 ft.) | |||||||||||||||||||||||||||||
Distribution |
w North America; nw Mexico
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CO; KS; NM; OK; TX
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Discussion | Subspecies 5 (5 in the flora). Oenothera cespitosa occurs in a wide array of habitats, from grassland, desert scrub, pinyon-juniper woodland, or Arizona chaparral to montane conifer forests, rarely at timberline, at elevations from (450–)800–3370 m. Oenothera cespitosa is self-incompatible (W. L. Wagner et al. 1985; Wagner 2005). Pachylophus nuttallii Spach is an illegitimate name that pertains here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera engelmannii is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). It has a relatively narrow distribution in sandy areas of eastern New Mexico and western Texas, extending to southeastern Colorado, western Oklahoma, and southwestern Kansas. The flower size seems to vary, with larger flowers in eastern New Mexico and considerably smaller flowers in the eastern part of its range. (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. Pachylophus | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra | ||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||
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Synonyms | Pachylophus cespitosus | Anogra pallida var. engelmannii, A. engelmannii | ||||||||||||||||||||||||||||
Name authority | Nuttall: Cat. Pl. Upper Louisiana, no. 53. (1813) | (Small) Munz: Amer. J. Bot. 18: 316. (1931) — (as engelmanni) | ||||||||||||||||||||||||||||
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