Oenothera macrocarpa |
Oenothera nuttallii |
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bigfruit evening primrose, Missouri evening primrose, Ozark sundrop |
Nuttall's evening primrose |
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Habit | Herbs caulescent, strigillose or glabrous, sometimes glandular puberulent distally; from a stout taproot, sometimes lateral roots producing adventitious shoots. | 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. | ||||||||||||||||
Stems | moderately leafy, (1–)4–40(–60) cm. |
erect, often branched, 30–100 cm. |
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Leaves | cauline, (2.8–)3.7–12.5(–17) × (0.1–)0.4–3(–4.5) cm; petiole (0.4–)1–4(–6) cm; blade linear, lanceolate-elliptic, elliptic to oblanceolate or suborbiculate, margins entire or conspicuously or inconspicuously denticulate or serrulate, sometimes undulate, apex usually acute, sometimes obtuse or retuse (subsp. incana). |
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. |
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Flowers | usually 1 or 2, rarely more, opening per day near sunset, fading next morning, sometimes (subspp. |
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. |
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Capsules | papery in age, narrowly ellipsoid to lanceoloid, sometimes twisted (subsp. fremontii), winged, wings (2–)10–28(–34) mm wide, body (13–)25–70(–115) × 2–9 mm, dehiscent 1/4–1/3 their length; pedicel 1–12(–25) mm. |
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. |
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Seeds | numerous, rarely as few as 8, in 1 row per locule, obovoid, (2–)3–5 × 1–2.3 mm. |
numerous, in 1 row per locule, reddish dark brown, narrowly obovoid, 1.5–2.3 mm. |
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Macrocarpa | and oklahomensis) lasting for 2 days, weakly scented; buds with unequal free tips 1–11(–15) mm; floral tube (21–)35–140(–160) mm; sepals (20–)25–65(–75) mm; petals bright yellow, fading orange, reddish orange or mostly unchanged, obovate to very broadly obovate, (17–)25–65(–68) mm, usually with terminal notch and/or tooth, margin sometimes erose; filaments 13–40(–44) mm, anthers 10–24(–25) mm; style (45–)55–192 mm, stigma usually exserted beyond anthers at anthesis. |
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2n | = 14, 28. |
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Oenothera macrocarpa |
Oenothera nuttallii |
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Phenology | Flowering Jun–Sep. | |||||||||||||||||
Habitat | Dry, sandy or rocky prairies, open wooded hillsides, disturbed areas, roadsides. | |||||||||||||||||
Elevation | 500–2200(–2900) m. (1600–7200(–9500) ft.) | |||||||||||||||||
Distribution |
c United States; n Mexico; s United States
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CO; IL; MI; MN; MT; ND; NE; SD; WI; WY; AB; MB; SK
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Discussion | Subspecies 5 (4 in the flora). Oenotheramacrocarpa is variable and has differentiated extensively in the Great Plains region. Each of the five distinctive subspecies occupies a different geographical and ecological situation. Only subsp. mexicana W. L. Wagner from Coahuila, Mexico, occurs outside of the flora area. In general, the subspecies are sharply distinct and each is characterized by a number of features, including pubescence, leaf features, flower and floral tube size, and size and morphology of the capsules and seeds. The five entities are treated as subspecies primarily because of their complete interfertility and extensive intergradation in any area of marginal contact. Intermediates are known between subsp. macrocarpa and subspp. fremontii and oklahomensis and between subspp. incana and oklahomensis. There is also some evidence that suggests past hybridization between subspp. fremontii and incana although there is no present contact between them. All subspecies are self-incompatible. Oenothera alata Nuttall (1818) is an illegitimate name based on O. macrocarpa and pertains here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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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. Megapterium | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | Megapterium macrocarpum, M. nuttallianum | O. albicaulis, O. albicaulis var. nuttallii | ||||||||||||||||
Name authority | Nuttall: Cat. Pl. Upper Louisiana, no. 56. (1813) | Sweet: Hort. Brit. ed. 2, 199. (1830) | ||||||||||||||||
Web links |