Oenothera cespitosa |
Oenothera rhombipetala |
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fragrant evening-primrose, tuft evening-primrose |
fourpoint 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 biennial, densely to sparsely strigillose, sometimes also sparsely glandular puberulent distally. | ||||||||||||||||||||||||||||
Stems | (when present), usually ascending or decumbent, unbranched or branched from near base, 0–40 cm. |
sometimes with lateral branches arising obliquely from rosette, 30–100(–150) 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, basal 6–20 × 0.6–2 cm, cauline 3–15 × 0.8–2.5 cm; blade narrowly oblanceolate, gradually narrowly elliptic to narrowly lanceolate, oblanceolate, or ovate distally, margins lobed to remotely dentate or subentire; bracts slightly longer than capsule they subtend. |
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Inflorescences | dense, usually without lateral branches, mature buds usually not overtopping spike apex. |
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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. |
2–several per spike opening per day near sunset; buds erect, with free tips erect, 0.5–3 mm; floral tube slightly curved upward to ± straight, 30–45 mm; sepals 15–30 mm; petals yellow, broadly elliptic to rhombic-elliptic, 15–35 mm; filaments 13–25 mm, anthers 3–8 mm, pollen 85–100% fertile; style 25–50 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. |
narrowly lanceoloid, 13–25 × 2.5–3 mm. |
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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. |
brown, sometimes flecked with dark red spots, ellipsoid, 1–1.7 × 0.4–0.7 mm. |
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2n | = 14, 28. |
= 14. |
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Oenothera cespitosa |
Oenothera rhombipetala |
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Phenology | Flowering May–Oct. | |||||||||||||||||||||||||||||
Habitat | Fields, prairies, sandy soil. | |||||||||||||||||||||||||||||
Elevation | 60–600(–1300) m. (200–2000(–4300) ft.) | |||||||||||||||||||||||||||||
Distribution |
w North America; nw Mexico
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AR; CO; IL; KS; MI; MN; MO; NE; NM; OK; SD; TX; WI
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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 rhombipetala is primarily a central plains species that has scattered localities in the Midwest to Illinois, Michigan, and Wisconsin, and barely entering the easternmost parts of Colorado and New Mexico. Oenothera rhombipetala had a broader delimitation (P. A. Munz 1965) until W. Dietrich and W. L. Wagner (1988) divided it into three species (O. clelandii, O. curtissii, and O. rhombipetala), with both of the split-off species being PTH. Evidence gathered by Dietrich and Wagner showed that these PTH species are geographically separated populations of small-flowered plants, and although they are very close morphologically, their distributions and morphological differences suggest that they were each derived independently from O. rhombipetala. Oenothera rhombipetala is self-incompatible. Oenothera pyramidalis H. Léveillé is a superfluous name and pertains 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. Pachylophus | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Candela | ||||||||||||||||||||||||||||
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Synonyms | Pachylophus cespitosus | O. heterophylla var. rhombipetala, O. leona, Raimannia rhombipetala | ||||||||||||||||||||||||||||
Name authority | Nuttall: Cat. Pl. Upper Louisiana, no. 53. (1813) | Nuttall ex Torrey & A. Gray: Fl. N. Amer. 1: 493. (1840) | ||||||||||||||||||||||||||||
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