Oenothera flava |
Oenothera hartwegii |
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long-tubed evening primrose, yellow evening primrose |
Fendler evening primrose, Hartweg's sundrops |
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Habit | Herbs perennial, rarely short-lived, acaulescent or very short-caulescent, glabrate to moderately strigillose, usually also glandular puberulent, sometimes sparsely hirsute distally; from a taproot. | Herbs perennial, sometimes suffrutescent, strigillose, glandular puberulent, glabrous, hirtellous, or short-pilose; from a stout taproot. | ||||||||||||||||
Stems | (when present) ascending, 1–several, usually densely leafy, 0–2 cm. |
1–many, erect to ascending, unbranched to densely branched, 4–60 cm. |
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Leaves | primarily in a basal rosette, (3.4–)6–30(–36) × (0.5–)1.5–5(–7) cm, flexible, sometimes ± fleshy; petiole (0.2–)2–7(–10) cm; blade oblanceolate to linear, margins usually irregularly and coarsely pinnately lobed, rarely subentire, apex acute. |
0.3–6.5 × 0.04–1.2 cm, sometimes fascicles of small leaves 0.1–1.5 cm present in non-flowering axils; petiole 0–0.2 cm; blade elliptic, lanceolate, linear, or filiform to ovate or oblanceolate, usually not much reduced distally, proximalmost leaves sometimes obovate to spatulate, base attenuate to obtuse, truncate, or subcordate, sometimes clasping, margins entire or serrate, often undulate, apex acute. |
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Flowers | 1–4 opening per day near sunset; buds with free tips (1–)2–10(–12) mm; floral tube (24–)40–200(–265) mm; sepals (8–)11–40(–42) mm; petals bright yellow, sometimes paler (in smaller-flowered plants), fading pale orange, drying purple, (7–)10–45(–50) mm; filaments (5–)8–23(–26) mm, anthers (2–)3–13(–16) mm; style (40–)50–250(–290) mm, stigma exserted beyond or surrounded by ring of anthers. |
usually 1 per stem opening per day in afternoon or near sunset; buds with free tips 0.5–6 mm; floral tube 16–50(–60) mm, funnelform in distal 1/2 or less; sepals 7–28 mm; petals yellow, fading pale pinkish or pale purple, 10–35 mm; filaments 4–13 mm, anthers 5–13 mm, pollen 85–100% fertile; style 25–65(–75) mm, stigma yellow, quadrangular, usually exserted beyond anthers. |
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Capsules | leathery in age, surface usually conspicuously reticulate, usually narrowly ovoid or ellipsoid, sometimes ovoid or lanceoloid, winged, wings narrowly oblong, (2–)3–5(–6) mm wide, confined to distal 2/3 of capsule, (10–)20–35(–43) × 4–8 mm (excluding wings), gradually constricted to a short beak, dehiscent 1/4–1/2 their length, valve surface usually conspicuously reticulate; sessile. |
6–40 × 2–4 mm, hard, promptly dehiscent throughout their length. |
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Seeds | asymmetrically cuneiform, 1.8–2.2(–2.6) mm.2n = 14. |
obovoid, 1–2.5 mm. |
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2n | = 14, 28. |
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Oenothera flava |
Oenothera hartwegii |
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Phenology | Flowering Mar–Aug(–Oct). | |||||||||||||||||
Habitat | Local and colonial, sometimes abundant in wet (at least seasonally moist) clay to gravelly sand of swales, desiccating flats and ponds, montane meadows, margins of permanent or seasonal watercourses, open sites. | |||||||||||||||||
Elevation | 300–3200 m. (1000–10500 ft.) | |||||||||||||||||
Distribution |
AZ; CA; CO; ID; MT; ND; NE; NM; NV; OR; SD; UT; WA; WY; AB; MB; SK; Mexico (Chihuahua, Durango, Guanajuato, Hidalgo, Jalisco, Sonora)
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c United States; sw United States; n Mexico
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Discussion | Petals in Oenothera flava typically range from 7–32 mm with floral tubes 24–100 mm; however, plants from three disjunct areas: the Mogollon Plateau in Arizona to Catron County, New Mexico; Sacramento Mountains and Sierra Blanca, Lincoln and Otero counties, New Mexico; and the Sierra Madre Occidental from northern Chihuahua south to Durango, have much larger petals (30–55 mm) and longer floral tubes (80–265 mm). They were originally recognized as a distinct species or most recently as a subspecies (O. flava subsp. taraxacoides), but detailed study of the variation pattern suggests that the larger flowers occur in areas of high hawkmoth species diversity and higher rates of outcrossing, similar to the pattern discussed in detail by D. P. Gregory (1963, 1964). R. A. Raguso et al. (2007) and H. E. Summers et al. (2015) came to the same conclusion in an independent study of floral biology of sect. Lavauxia. Because populations from the three disjunct areas appear to have diverged independently from lower-elevation source populations, it seems best to treat the complex as one variable species without any formal subdivision. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 5 (5 in the flora). Oenothera hartwegii consists of five intergrading subspecies, which are generally locally common on rocky, sandy, gypsum, or limestone soil in arid to relatively mesic open areas, in southeastern Colorado, southwestern Kansas, western Oklahoma, Texas (except eastern part), New Mexico, southeastern and east-central Arizona, and in Mexico from Chihuahua, northern Coahuila, and northwestern Tamaulipas south to Aguascalientes. H. F. Towner (1977) found that O. hartwegii is self-incompatible and usually vespertine; two of the subspecies (filifolia and maccartii) open early in the afternoon and are pollinated both day and evening. (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 | ||||||||||||||||||
Sibling taxa | ||||||||||||||||||
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Synonyms | Lavauxiaflava a., L. palustris, L. taraxacoides, O. flava subsp. taraxacoides, O. murdockii, O. taraxacoides, O. triloba var. ecristata | Calylophus hartwegii, Galpinsia hartwegii, Salpingia hartwegii | ||||||||||||||||
Name authority | (A. Nelson) Garrett: Spring Fl. Wasatch ed. 4, 106. (1927) | Bentham: Pl. Hartw., 5. (1839) — (as hartwegi) | ||||||||||||||||
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