Oenothera pilosella |
Oenothera pubescens |
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meadow evening-primrose |
pubescent evening primrose, silky evening primrose, South American evening-primrose |
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Habit | Herbs perennial, usually densely to sparsely hirsute, rarely glabrous; from a thickened base, rhizomatous. | Herbs annual or biennial, densely to sparsely strigillose, sometimes also villous and glandular puberulent distally; from a taproot. |
Stems | spreading or ascending, unbranched or few-branched distally, 20–80 cm. |
unbranched or with branched central stem and ascending to decumbent lateral branches arising from rosette, 5–50(–80) cm. |
Leaves | 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. |
in a basal rosette and cauline, basal 5–14 × 0.5–2.5 cm, cauline 2–8 × 0.5–2.5 cm; blade narrowly oblanceolate to narrowly elliptic or narrowly oblong, margins usually dentate to deeply lobed; bracts spreading, flat. |
Inflorescences | erect, flowers in axils of distalmost few nodes. |
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Flowers | 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. |
usually 1 opening per day near sunset; buds with free tips erect, 0.1–1 mm; floral tube erect, becoming recurved and nodding, then erect again just before anthesis, 15–50 mm; sepals 5–25 mm; petals yellow, fading reddish orange, broadly obovate to obcordate, 5–25(–35) mm; filaments 6–18 mm, anthers (2–)3–9 mm, pollen ca. 50% fertile; style 20–60 mm, stigma surrounded by or slightly exserted beyond anthers at anthesis. |
Capsules | 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. |
cylindrical, sometimes slightly enlarged distally, 20–45 ×2–4 mm. |
Seeds | 1 × 0.5 mm. |
brown, sometimes dark-flecked, 0.9–1.5 × 0.6–1 mm. |
2n | = 56. |
= 14. |
Oenothera pilosella |
Oenothera pubescens |
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Phenology | Flowering May–Jul(–Aug). | Flowering (Feb–)Apr–Sep(–Oct). |
Habitat | Open fields, edge of woods, marshes and bottomland prairies, open disturbed sites, ditches, old fields, railroads, roadsides. | Open sites in montane habitats. |
Elevation | 100–600 m. (300–2000 ft.) | (1300–)1500–2500(–3100) m. ((4300–)4900–8200(–10200) ft.) |
Distribution |
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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AZ; NM; TX; Mexico; West Indies; Central America (Guatemala); South America (Colombia, Ecuador, Peru)
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Discussion | 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.) |
Oenothera pubescens is a PTH species and forms a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous (W. Dietrich and W. L. Wagner 1988). Oenothera pubescens has been collected once in California in 1884 (Newberry Springs, San Bernardino County), where it was temporarily introduced or a natural occurrence that was extirpated. Collections from west Texas (Brewster, Jeff Davis, and Presidio counties) have been made since 1990 and a few others collected earlier were misidentified as O. laciniata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kneiffia | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Nutantigemma |
Sibling taxa | ||
Synonyms | Kneiffia fruticosa var. pilosella, K. pilosella, K. pratensis, K. sumstinei, O. fruticosa var. hirsuta, O. fruticosa var. pilosella, O. pratensis | Anogra amplexicaulis, O. amplexicaulis, O. laciniata subsp. pubescens, Var. o. var. o., O. nyctaginiifolia, O. stuebelii, Raimannia colimae, R. confusa |
Name authority | Rafinesque: Ann. Nat. 1: 15. (1820) | Willdenow ex Sprengel: Syst. Veg. 2: 229. (1825) |
Web links |