Oenothera perennis
Syst. Nat. ed. 10, 2: 998. 1759.
Herbs perennial, sparsely to moderately strigillose, glandular puberulent distally; from fibrous-roots. Stems usually erect to slightly decumbent, unbranched to few-branched distally, (3–) 15–30 (–75) cm. Leaves in a basal rosette and cauline, basal 2–4 × 0.2–1.2 cm, petiole (0.2–) 0.5–1.2 (–2.5) cm, blade oblanceolate to obovate; cauline 3–7 × 0.2–1.2 cm, petiole 0.1–1 cm, blade oblanceolate to obovate, margins entire or weakly and remotely denticulate. Inflorescences nodding, flowers in axils of distalmost few nodes. Flowers opening near sunrise, nearly unscented; buds with free tips to 1 mm, connivent; floral-tube 3–10 mm; sepals 2–4 mm; petals bright-yellow, fading pale-yellow, or orangish yellow to pale-pink, 5–10 mm; filaments 3–4 mm, anthers 1–2 mm, pollen 40–70% fertile; style 3–4 mm, stigma surrounded by anthers at anthesis. Capsules clavate, 4-angled or narrowly 4-winged, 5–10 × 2–3 mm, stipe 1–2 mm; sessile. Seeds 0.7–0.8 × 0.2–0.3 mm. 2n = 14.
Phenology: Flowering May–Jul(–Aug).
Habitat: Fields, open woods, boggy areas.
Elevation: (0–)150–900(–1400) m.
Distribution
St. Pierre and Miquelon, B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Conn., Del., D.C., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.H., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.
Discussion
Oenothera perennis, a PTH species that forms a ring of 14 chromosomes in meiosis, is self-compatible and autogamous (G. B. Straley 1977). It is disjunct in Nebraska from the rest of its range in eastern North America, occurring in Garfield, Holt, and Rock counties (R. Kaul, pers. comm.). It is introduced in British Columbia.
Oenotherapumila Linnaeus is an illegitimate substitution based on O. perennis Linnaeus, while Kneiffia michauxii Spach is an illegitimate substitution based O. pumila, as is K. pumila Spach, and the three pertain here.
Selected References
None.