Oenothera capillifolia |
Oenothera nutans |
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nodding 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, often appearing glabrous to naked eye, usually strigillose and sparsely to moderately villous proximal to inflorescence, hairs translucent and with or without pustules, pustules not red (in fresh material), inflorescence glabrous, glandular puberulent, or strigillose and glandular puberulent. | ||||
Stems | 1–many, weakly decumbent to ascending or erect, unbranched to moderately branched, (10–)25–80 cm. |
erect, red on proximal parts, green on distal ones, rarely red throughout, unbranched or with branches obliquely arising from rosette and secondary branches arising from main stem, 30–200 cm. |
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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 10–32 × 3–7 cm, cauline 6–20 × 2–8 cm; blade green to pale green, narrowly oblanceolate to narrowly obovate, or narrowly elliptic, sometimes lanceolate distally, margins usually flat, rarely undulate, bluntly dentate, teeth widely spaced, sometimes sinuate-dentate proximally; bracts caducous. |
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Inflorescences | erect, unbranched or with secondary branches just proximal to main one. |
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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, 4–6 mm diam., with free tips terminal, erect, 1.5–6 mm; floral tube 30–43 mm; sepals yellowish green or flushed with red, 10–23 mm; petals yellow to pale yellow, fading pale yellowish white, very broadly obcordate, 14–25(–30) mm; filaments 10–25 mm, anthers 4–10 mm, pollen ca. 50% fertile; style 35–63 mm, stigma surrounded by 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. |
erect or slightly spreading, dull green when dry, narrowly lanceoloid to narrowly ovoid, 12–36 × 3–6 mm, free tips of valves 1–1.5 mm. |
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Seeds | obovoid, 1–1.8 mm, sharply angled, apex truncate. |
1–1.9 × 0.6–0.9 mm. |
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2n | = 14. |
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Oenothera capillifolia |
Oenothera nutans |
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Phenology | Flowering Jun–Aug(–Sep). | |||||
Habitat | Open, often disturbed sites, stream beds, flood plains, slopes, margins of mixed deciduous forests, roadsides, old fields. | |||||
Elevation | (200–)400–1700 m. ((700–)1300–5600 ft.) | |||||
Distribution | c United States; sc United States; n Mexico |
AL; AR; CT; DE; FL; GA; IN; KY; MA; MD; ME; MI; MO; NC; NH; NJ; NY; OH; PA; SC; TN; VA; VT; WV; ON |
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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 nutans is a PTH species and forms a ring of 14 chromosomes or a ring of 12 and 1 bivalent in meiosis, and is self-compatible and autogamous (W. Dietrich et al. 1997). It has plastome III and a BB genome composition. The disjunct occurrences of O. nutans in Arkansas and Missouri probably represent unintentional introductions by humans. (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. austromontana, O. biennis subsp. austromontana, O. biennis var. austromontana, O. biennis var. nutans | ||||
Name authority | Scheele: Linnaea 21: 576. (1848) | G. F. Atkinson & Bartlett: Rhodora 15: 83. (1913) | ||||
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