Oenothera linifolia |
Oenothera fruticosa |
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threadleaf evening-primrose, threadleaf sundrop |
narrow-leaf 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 perennial, moderately to densely strigillose and/or villous, glandular puberulent, or glabrous; from fibrous roots, not or rarely producing rhizomes. | ||||
Stems | unbranched or with many ascending branches arising near base, erect, 10–50 cm. |
erect to decumbent, branched or unbranched, (10–)30–80 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. |
in a basal rosette and cauline, rosette usually withered by anthesis, surfaces sometimes glaucous, especially abaxially, basal 3–12 × 0.5–3 cm, petiole 1–4 cm, blade oblanceolate to obovate, margins subentire, dentate, or denticulate, sometimes undulate; cauline 2–6(–11) × (0.1–)0.5–2(–5) cm, petiole 0.1–2(–6) cm, blade linear, lanceolate to oblanceolate, narrowly elliptic, or ovate, margins subentire or dentate or denticulate, sometimes undulate. |
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Inflorescences | usually erect, rarely nodding, flowers in axils of distalmost few nodes. |
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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 near sunrise; buds with free tips 0.5–8(–13) mm, connivent, sometimes spreading; floral tube 5–20 mm; sepals 5–20 mm; petals pale to bright yellow, fading pale pink, orangish pink, or yellow, (8–)15–25(–30) mm; filaments 5–15 mm, anthers 4–7 mm, pollen 85–100% fertile; style 12–20 mm, stigma 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. |
clavate to oblong-clavate or oblong-ellipsoid, 4-angled to 4-winged, (5–)10–17(–20) × (2–)3–4(–6) mm, stipe 0.1–10 mm; sessile. |
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Seeds | clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm. |
1 × 0.5 mm. |
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2n | = 14. |
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Oenothera linifolia |
Oenothera fruticosa |
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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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e North America; c North America
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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 fruticosa as delimited here is a polymorphic species. Previous classification of this group has undergone numerous reorganizations due to the difficulties in separating populations into discrete morphological taxa. In the past it has most frequently been treated as two species, O. fruticosa and O. tetragona Roth, often with a dozen or more infraspecific taxa recognized. The broad delimitation of G. B. Straley (1977) is followed here with one species consisting of two subspecies that appear to intergrade extensively across a wide area of overlap. Straley determined O. fruticosa to be self-incompatible and polyploid. (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. Kneiffia | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium | Kneiffia fruticosa | ||||
Name authority | Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) | Linnaeus: Sp. Pl. 1: 346. (1753) | ||||
Web links |