Oenothera linifolia |
Oenothera capillifolia |
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threadleaf evening-primrose, threadleaf sundrop |
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Habit | Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. | Herbs perennial (short-lived or, sometimes, suffrutescent) or annual, glabrous or strigillose; from a stout taproot. | ||||
Stems | unbranched or with many ascending branches arising near base, erect, 10–50 cm. |
1–many, weakly decumbent to ascending or erect, unbranched to moderately branched, (10–)25–80 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. |
1–9 × (0.1–)0.3–1 cm, sometimes fascicles of small leaves to 2 cm present in non-flowering axils; petiole 0–0.6 cm; blade linear to narrowly lanceolate or oblanceolate, often folded lengthwise, usually not much reduced distally, proximalmost leaves sometimes spatulate, base attenuate, margins subentire or serrulate or spinulose-serrate, apex acute. |
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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. |
opening at sunrise; buds with free tips 0–4 mm; floral tube 5–20 mm; sepals 4–12 mm, midribs keeled; petals yellow, fading orangish to purplish, 6–25 mm; antisepalous filaments 2–8 mm, antipetalous filaments 1–4 mm, anthers 2–7 mm, pollen 90–100% fertile; style 9–30 mm, stigma sometimes blue-black, discoid to quadrangular, exserted beyond anthers. |
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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. |
10–35 × 1–2 mm, hard, dehiscent 1/2 their length, often tardily dehiscent throughout their length. |
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Seeds | clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm. |
obovoid, 1–1.8 mm, sharply angled, apex truncate. |
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2n | = 14. |
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Oenothera linifolia |
Oenothera capillifolia |
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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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c United States; sc United States; n Mexico |
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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). Oenothera capillifolia is self-incompatible (H. F. Towner 1977). Oenothera berlandieri (Spach) Steudel 1841, not D. Dietrich 1840, is superfluous and cannot be used in Oenothera when transferred from Calylophus, and pertains here. (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. Calylophus > subsect. Calylophus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium | Meriolix capillifolia | ||||
Name authority | Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) | Scheele: Linnaea 21: 576. (1848) | ||||
Web links |