Oenothera capillifolia |
Oenothera argillicola |
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shale barren evening primrose |
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Habit | Herbs perennial (short-lived or, sometimes, suffrutescent) or annual, glabrous or strigillose; from a stout taproot. | 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. | ||||
Stems | 1–many, weakly decumbent to ascending or erect, unbranched to moderately branched, (10–)25–80 cm. |
erect to ascending, green or red, unbranched or with branches obliquely arising from rosette or in distal 1/2 of main stem. |
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Leaves | 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. |
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. |
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Inflorescences | curved with ascending tip, unbranched. |
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Flowers | 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. |
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. |
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Capsules | 10–35 × 1–2 mm, hard, dehiscent 1/2 their length, often tardily dehiscent throughout their length. |
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. |
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Seeds | obovoid, 1–1.8 mm, sharply angled, apex truncate. |
1.3–1.9 × 0.7–1.1 mm. |
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2n | = 14. |
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Oenothera capillifolia |
Oenothera argillicola |
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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 | c United States; sc United States; n Mexico |
MD; PA; VA; WV |
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Discussion | 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.) |
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.) |
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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. Calylophus > subsect. Calylophus | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Oenothera | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Meriolix capillifolia | O. argillicola var. pubescens | ||||
Name authority | Scheele: Linnaea 21: 576. (1848) | Mackenzie: Torreya 4: 56. (1904) | ||||
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