Oenothera argillicola |
Oenothera heterophylla |
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shale barren evening primrose |
variableleaf evening primrose |
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Habit | Herbs biennial or short-lived perennial, strigillose and sparsely to moderately villous, hairs sometimes pustulate, pustules with green or red bases, inflorescence glabrous or sparsely glandular puberulent, sometimes also sparsely villous. | 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 | erect to ascending, green or red, unbranched or with branches obliquely arising from rosette or in distal 1/2 of main stem. |
unbranched or branched mainly in distal part, 25–70 cm. |
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Leaves | in a basal rosette and cauline, basal 7–25 × 0.7–2 cm, cauline 6–13 × 0.4–1 cm; blade dark green, somewhat glossy, very narrowly oblanceolate to narrowly oblanceolate, linear-elliptic, lanceolate, or nearly linear, margins flat, entire or remotely and bluntly dentate, sometimes with larger teeth near base; bracts persistent. |
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 | curved with ascending tip, unbranched. |
dense, often with several lateral branches, mature buds usually overtopping spike apex. |
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Flowers | opening near sunset; buds erect, 4–8 mm diam., with free tips subterminal, divergent and hornlike, 3–9 mm; floral tube 32–52 mm; sepals yellowish green to yellow, sometimes flushed with red, especially at apex, 27–38 mm; petals yellow to pale yellow, fading pale yellow to pale yellowish orange, very broadly obcordate or obovate, 25–42 mm; filaments 20–27 mm, anthers 9–13 mm, pollen 90–100% fertile; style 60–85 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. |
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Capsules | spreading at nearly a right angle to stem, curved upward, sometimes secund, dull green or rusty brown when dry, narrowly lanceoloid to lanceoloid, 20–40 × 4–6 mm, free tips of valves 1–2 mm. |
lanceoloid, 13–25 × 2.5–4 mm. |
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Seeds | 1.3–1.9 × 0.7–1.1 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 argillicola |
Oenothera heterophylla |
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Phenology | Flowering (Jun–)Jul–Oct. | |||||
Habitat | Open sites on Devonian Brallier shale slopes, barrens, outcrops or adjacent roadsides in mid-Appalachian Allegheny Mountains. | |||||
Elevation | 150–700 m. (500–2300 ft.) | |||||
Distribution |
MD; PA; VA; WV |
s United States |
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Discussion | Oenothera argillicola is one of eight angiosperm species restricted to the Devonian Brallier shale barrens, but among them only O. argillicola and Trifolium virginicum occur throughout the shale barren region. Oenothera argillicola has plastome V and a CC genome composition. (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 | ||||||
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Synonyms | O. argillicola var. pubescens | Raimannia heterophylla | ||||
Name authority | Mackenzie: Torreya 4: 56. (1904) | Spach: Nouv. Ann. Mus. Hist. Nat. 4: 348. (1836) | ||||
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