Oenothera linifolia |
Oenothera heterophylla |
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threadleaf evening-primrose, threadleaf sundrop |
variableleaf evening primrose |
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Habit | Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. | 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 | unbranched or with many ascending branches arising near base, erect, 10–50 cm. |
unbranched or branched mainly in distal part, 25–70 cm. |
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Leaves | in a basal rosette and cauline, basal 1–2(–4) × 0.2–0.6 cm, petiole 0.2–1(–1.5) cm, blade ovate to obovate or narrowly elliptic; cauline 1–4 × less than 0.1 cm, sessile, blade linear or filiform. |
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. |
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Inflorescences | dense, often with several lateral branches, mature buds usually overtopping spike apex. |
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Flowers | usually 1–3 opening per day near sunrise; buds without free tips; sepals 1.5–2 mm; petals bright yellow, fading pink, obcordate to obovate, 3–5(–7) mm; filaments 1–2 mm, anthers 0.5–1 mm; style 1–2 mm, stigma surrounded by 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. |
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Capsules | ellipsoid-rhombic to subglobose, 4-angled, 4–6(–10) × 1.5–3 mm, stipe 0–4 mm, valve midrib raised at distal end, indehiscent or tardily dehiscent distally; sessile. |
lanceoloid, 13–25 × 2.5–4 mm. |
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Seeds | clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm. |
brown, often flecked with darker spots, ellipsoid to broadly ellipsoid, 1.1–1.8 × 0.4–0.8 mm. |
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2n | = 14. |
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Oenothera linifolia |
Oenothera heterophylla |
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Phenology | Flowering Apr–Jun(–Aug). | |||||
Habitat | Prairies, open woodlands, open rocky and sandy sites, roadsides. | |||||
Elevation | 0–400 m. (0–1300 ft.) | |||||
Distribution |
AL; AR; FL; GA; IL; KS; KY; LA; MO; MS; NC; OK; SC; TN; TX
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s United States |
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Discussion | Kneiffia linearifolia Spach (1835) is an illegitimate name based on Oenothera linifolia. (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.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Peniophyllum | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Candela | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium | Raimannia heterophylla | ||||
Name authority | Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) | Spach: Nouv. Ann. Mus. Hist. Nat. 4: 348. (1836) | ||||
Web links |