Oenothera pilosella |
Oenothera heterophylla |
|||||
---|---|---|---|---|---|---|
meadow evening-primrose |
variableleaf evening primrose |
|||||
Habit | Herbs perennial, usually densely to sparsely hirsute, rarely glabrous; from a thickened base, rhizomatous. | Herbs annual or short-lived perennial, sparsely to densely strigillose, inflorescence sometimes also sparsely glandular puberulent, villous, or sparsely hirsute with spreading, pustulate-based hairs, or sometimes glabrate. | ||||
Stems | spreading or ascending, unbranched or few-branched distally, 20–80 cm. |
unbranched or branched mainly in distal part, 25–70 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 7–15 × 1–2.5 cm, cauline 3–13 ×0.4–2.3 cm; blade narrowly oblanceolate to oblanceolate, gradually narrowly lanceolate to lanceolate or elliptic distally, margins deeply lobed to remotely dentate or subentire; bracts longer than capsule they subtend, 1–3 cm. |
||||
Inflorescences | erect, flowers in axils of distalmost few nodes. |
dense, often with several lateral branches, mature buds usually overtopping spike apex. |
||||
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. |
2–several per spike opening per day near sunset; buds erect, with free tips erect or spreading, 1–6 mm; floral tube nearly straight, 25–47 mm; sepals 15–30 mm; petals yellow, broadly elliptic to nearly rhombic, 18–35 mm; filaments 15–30 mm, anthers 3–8 mm, pollen 85–100% fertile; style 45–75 mm, stigma usually 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. |
lanceoloid, 13–25 × 2.5–4 mm. |
||||
Seeds | 1 × 0.5 mm. |
brown, often flecked with darker spots, ellipsoid to broadly ellipsoid, 1.1–1.8 × 0.4–0.8 mm. |
||||
2n | = 56. |
|||||
Oenothera pilosella |
Oenothera heterophylla |
|||||
Phenology | Flowering May–Jul(–Aug). | |||||
Habitat | Open fields, edge of woods, marshes and bottomland prairies, open disturbed sites, ditches, old fields, railroads, roadsides. | |||||
Elevation | 100–600 m. (300–2000 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
|
s United States |
||||
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.) |
Subspecies 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||
Key |
|
|||||
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. Candela | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Kneiffia fruticosa var. pilosella, K. pilosella, K. pratensis, K. sumstinei, O. fruticosa var. hirsuta, O. fruticosa var. pilosella, O. pratensis | Raimannia heterophylla | ||||
Name authority | Rafinesque: Ann. Nat. 1: 15. (1820) | Spach: Nouv. Ann. Mus. Hist. Nat. 4: 348. (1836) | ||||
Web links |