Oenothera gayleana |
Oenothera pilosella |
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meadow evening-primrose |
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Habit | Herbs perennial, sometimes suffrutescent, usually strigillose, sometimes glabrous; from a stout taproot. | Herbs perennial, usually densely to sparsely hirsute, rarely glabrous; from a thickened base, rhizomatous. |
Stems | many, ascending to erect, branched from base, 15–30(–40) cm. |
spreading or ascending, unbranched or few-branched distally, 20–80 cm. |
Leaves | 2.5–3.5 × 0.1–0.2 cm, rarely fascicles of small leaves present in non-flowering axils; petiole 0–0.1 cm; blade linear to narrowly linear-lanceolate, folded lengthwise, base long-attenuate, margins subentire or serrulate, apex acute. |
in a basal rosette and cauline, basal 4–8 × 2–5 cm, petiole (0.5–)1–3(–4) cm, blade oblanceolate to ovate, margins entire; cauline 3–10(–13) × 1–2(–4) cm, petiole 0–0.5(–2) cm, blade lanceolate to ovate, abruptly narrowed to base, margins subentire or coarsely dentate. |
Inflorescences | erect, flowers in axils of distalmost few nodes. |
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Flowers | opening near sunrise; buds with free tips 0–0.5 mm; floral tube 7 mm; sepals 4–6 mm, midribs keeled; petals yellow, fading yellow to orange, 15–20 mm; antisepalous filaments 5 mm, antipetalous filaments 2 mm, anthers 3–4 mm, pollen 90–100% fertile; style 10 mm, stigma discoid to quadrangular, exserted beyond anthers at anthesis. |
opening near sunrise; buds with free tips 1–3 mm, spreading; floral tube 10–25 mm; sepals 10–20 mm; petals bright yellow, fading pale pink or pale yellow, 15–30 mm; filaments 7–15 mm, anthers 4–8 mm, pollen 85–100% fertile; style 10–20 mm, stigma exserted beyond anthers at anthesis. |
Capsules | 18–20 × 2 mm, hard, dehiscent 1/2 their length, often tardily dehiscent throughout their length. |
usually oblong-clavate to oblong-ellipsoid or ellipsoid, 4-angled or weakly 4-winged, (5–)10–15(–28) × 2–4(–5) mm, stipe (1–)3–5(–9) mm; sessile. |
Seeds | oblanceoloid, 1–1.8 mm, sharply angled, apex truncate. |
1 × 0.5 mm. |
2n | = 14. |
= 56. |
Oenothera gayleana |
Oenothera pilosella |
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Phenology | Flowering May–Sep. | Flowering May–Jul(–Aug). |
Habitat | Gypsum outcrops. | Open fields, edge of woods, marshes and bottomland prairies, open disturbed sites, ditches, old fields, railroads, roadsides. |
Elevation | 500–1400 m. (1600–4600 ft.) | 100–600 m. (300–2000 ft.) |
Distribution |
NM; TX |
AL; AR; CT; IA; IL; IN; KY; LA; MA; ME; MI; MO; MS; NH; NY; OH; OK; PA; RI; VA; VT; WI; WV; ON
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Discussion | Oenothera gayleana is a recently discovered gypsum endemic known only from scattered outcrops from De Baca and Eddy counties in New Mexico, and Culberson County in Texas. When published, the delimitation of O. gayleana included populations in Collinsworth and Dickens counties in the Texas panhandle, and adjacent Harmon County in Oklahoma. Subsequent study (B. Cooper et al., unpubl.) has determined they are actually O. serrulata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera pilosella is widespread in cultivation in gardens and frequently escapes and becomes naturalized; the northern and eastern natural limits of O. pilosella are not clear. According to G. B. Straley (1977) the natural limits are from Wayne County, West Virginia, along the Ohio River and Erie County, New York, for the eastern limits, and Tuscola County, Michigan, and Manitowoc County, Wisconsin, for the northern limits. K. N. Krakos (2014), based on new field studies and phylogenetic data, found that O. pilosella does not form a monophyletic group with plants previously treated by Straley as O. pilosella subsp. sessilis in molecular analyses, and thus is here reinstated as the distinct species O. sessilis. Straley determined that O. pilosella is self-incompatible and an octoploid, one of the few in the genus. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Kneiffia fruticosa var. pilosella, K. pilosella, K. pratensis, K. sumstinei, O. fruticosa var. hirsuta, O. fruticosa var. pilosella, O. pratensis | |
Name authority | B. L. Turner & M. J. Moore: Phytologia 96: 200, figs. 1, 2. (2014) | Rafinesque: Ann. Nat. 1: 15. (1820) |
Web links |