Oenothera pilosella |
Oenothera harringtonii |
|
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meadow evening-primrose |
Colorado Springs evening primrose |
|
Habit | Herbs perennial, usually densely to sparsely hirsute, rarely glabrous; from a thickened base, rhizomatous. | Herbs robust spring annual or, rarely, surviving a second year, caulescent, hirtellous, also glandular puberulent; from stout taproot. |
Stems | spreading or ascending, unbranched or few-branched distally, 20–80 cm. |
ascending to erect, stout, unbranched or with lateral stems from basal rosette, densely leafy, 15–30 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. |
10–14(–14.5) × 1.5–2.3(–3) cm; petiole 4.3–6.6 cm; blade narrowly oblanceolate, margins irregularly and coarsely dentate, apex acute. |
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 5–10 per stem opening per day near sunset, with heavy, sweet scent; buds erect; floral tube 31–60 mm; sepals 17–26 mm; petals white, fading pale pink, 20–26 mm; filaments 11–16 mm, anthers 8–11 mm; style 65–96 mm, stigma 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. |
straight, lanceoloid, obtusely 4-angled, (21–)25–30(–35) × (5–)6–8 mm, tapering to a sterile beak 6–8 mm, dehiscent 1/2–2/3 their length, valve margins with 5–8 conspicuous, irregular tubercles, sometimes 2 or more coalesced into a sinuate ridge, also with conspicuous medial ridge throughout; pedicel 0.5–1 mm. |
Seeds | 1 × 0.5 mm. |
numerous, usually in 2 distinct rows per locule, sometimes rows partially overlapping, narrowly obovoid, 2.1–2.3 × 1–1.3 mm, embryo slightly less than 1/2 seed volume, surface appearing finely striate but papillose under magnification; seed collar with membrane intact at maturity, membrane rarely splitting and separating from collar, margin entire. |
2n | = 56. |
= 14. |
Oenothera pilosella |
Oenothera harringtonii |
|
Phenology | Flowering May–Jul(–Aug). | Flowering May–Jun. |
Habitat | Open fields, edge of woods, marshes and bottomland prairies, open disturbed sites, ditches, old fields, railroads, roadsides. | On compacted, silty clay to looser rocky and sandy soil in open grassland. |
Elevation | 100–600 m. (300–2000 ft.) | 1400–1900 m. (4600–6200 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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CO |
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 harringtonii is known only from southeastern Colorado from western El Paso and eastern Fremont counties, southeast through Pueblo to Otero counties, and south to Las Animas County; it may also occur in adjacent Colfax and Union counties in New Mexico but has not been collected there. Oenothera harringtonii is self-incompatible (W. L. Wagner et al. 1985; Wagner 2005). (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. Pachylophus |
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 | Rafinesque: Ann. Nat. 1: 15. (1820) | W. L. Wagner, Stockhouse & W. M. Klein: Ann. Missouri Bot. Gard. 70: 195. (1983) |
Web links |