Oenothera nuttallii |
Oenothera engelmannii |
|
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Nuttall's evening primrose |
Engelmann's evening-primrose |
|
Habit | Herbs perennial, mostly glabrous, sometimes strigillose on leaves and/or glandular puberulent on distal parts, at least on floral tube; from a taproot, lateral roots producing adventitious shoots. | Herbs winter-annual, conspicuously villous throughout, also strigillose on leaves and distal parts; from a taproot. |
Stems | erect, often branched, 30–100 cm. |
erect, unbranched or with few, spreading branches, 30–50(–80) cm. |
Leaves | in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, 2–6(–10.5) × 0.3–0.6(–1) cm; petiole 0–2 cm; blade narrowly oblong to oblong-lanceolate, margins usually entire, sometimes remotely denticulate or repand-denticulate. |
in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, (1–)2–6(–8) × 1–2(–3) cm; sessile; blade lanceolate to oblong lanceolate, proximal ones sometimes oblanceolate, margins coarsely repand-dentate or -pinnatifid. |
Flowers | 1–several opening per day near sunset; buds nodding, weakly quadrangular, with free tips 1–2 mm; floral tube 15–40 mm; sepals 20–30 mm, not spotted; petals white, fading pink, broadly obovate or obcordate,15–30 mm; filaments 15–18 mm, anthers 8–10 mm; style 35–45 mm, stigma exserted beyond anthers at anthesis. |
1–several opening per day near sunset; buds nodding, weakly quadrangular, without free tips; floral tube 20–30 mm; sepals 13–21 mm, not spotted or with scattered small, maroon spots; petals white, fading pink, broadly obovate or obcordate, 15–30 mm; filaments 14–16 mm, anthers 6–8 mm; style 40–50 mm, stigma exserted beyond anthers at anthesis. |
Capsules | erect or ascending, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering slightly from base to apex, 20–30 × 2–3 mm; sessile. |
widely spreading, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering gradually from base to apex, 30–60 × 2–3 mm; sessile. |
Seeds | numerous, in 1 row per locule, reddish dark brown, narrowly obovoid, 1.5–2.3 mm. |
numerous, in 1 row per locule, brown, narrowly obovoid, 1–1.5 mm. |
2n | = 14, 28. |
= 14. |
Oenothera nuttallii |
Oenothera engelmannii |
|
Phenology | Flowering Jun–Sep. | Flowering Apr–Aug(–Sep). |
Habitat | Dry, sandy or rocky prairies, open wooded hillsides, disturbed areas, roadsides. | Sandy prairies, dunes, disturbed areas, roadsides. |
Elevation | 500–2200(–2900) m. (1600–7200(–9500) ft.) | 500–1300 m. (1600–4300 ft.) |
Distribution |
CO; IL; MI; MN; MT; ND; NE; SD; WI; WY; AB; MB; SK
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CO; KS; NM; OK; TX
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Discussion | Oenothera nuttallii had been assumed to be self-incompatible (W. L. Wagner et al. 2007), but K. E. Theiss et al. (2010) determined two plants to be self-compatible. Anogra nuttalliana Spach and Baumannia nuttalliana Spach are illegitimate names that pertain here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera engelmannii is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). It has a relatively narrow distribution in sandy areas of eastern New Mexico and western Texas, extending to southeastern Colorado, western Oklahoma, and southwestern Kansas. The flower size seems to vary, with larger flowers in eastern New Mexico and considerably smaller flowers in the eastern part of its range. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra |
Sibling taxa | ||
Synonyms | O. albicaulis, O. albicaulis var. nuttallii | Anogra pallida var. engelmannii, A. engelmannii |
Name authority | Sweet: Hort. Brit. ed. 2, 199. (1830) | (Small) Munz: Amer. J. Bot. 18: 316. (1931) — (as engelmanni) |
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