Oenothera rosea
Oenothera flava
pink evening primrose, rose evening-primrose
long-tubed evening primrose, yellow evening primrose
1–several, ascending to decumbent, 7–65 cm.
(when present) ascending, 1–several, usually densely leafy, 0–2 cm.
in a basal rosette and cauline, basal 1–6 × 0.3–2 cm, blade narrowly elliptic to elliptic or ovate, margins subentire, weakly serrulate, or sinuate-pinnatifid;
cauline 1–6 × 0.3–2 cm, blade narrowly elliptic to narrowly ovate, margins subentire or weakly serrulate, proximal ones sinuate-pinnatifid.
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.
erect.
1–3 opening per day near sunrise;
buds with free tips 0.1–1 mm;
floral tube 4–8 mm;
sepals 6–12 mm;
petals rose purple, fading darker, 4–12 mm;
filaments 4–6 mm, anthers 2–3.5 mm, pollen 35–65% fertile;
style 7–13.5 mm, stigma surrounded by anthers at anthesis.
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.
narrowly obovoid, 4–12 × 2–4 mm, apex attenuate to a sterile beak, proximal stipe 5–20 mm, gradually tapering to base, valve midrib prominent in distal part;
sessile.
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.
narrowly obovoid, 0.5–0.9 × 0.3–0.5 mm.
asymmetrically cuneiform, 1.8–2.2(–2.6) mm.2n = 14.
= 14.
Oenothera rosea
Oenothera flava
Oenothera rosea is a PTH species, forming a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous. In the flora area, it is known from Cochise, Pima, and Santa Cruz counties in Arizona, Alameda, Los Angeles, Riverside, San Bernardino, San Diego, San Francisco, and Santa Barbara counties in California (primarily in urban areas), and from southern Texas. It is clearly of North American origin, since all of its close relatives are confined to North America, and has spread south along the Andes. It occurs at 500–3700 m in South America but generally at lower elevations in most areas.
The name Hartmannia affinis Spach is illegitimate, being based on Oenothera virgata; H. gauroides Spach is also illegitimate, being based on O. rosea; O. purpurea Lamarck is a later homonym; these three names pertain here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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