Oenothera triloba
Oenothera rosea
stemless evening-primrose
pink evening primrose, rose evening-primrose
(when present) ascending, 1–several, densely leafy, 0–20 cm.
1–several, ascending to decumbent, 7–65 cm.
in a basal rosette, sometimes also cauline, (2.5–)6–25(–32) × (0.6–)1.5–4(–5) cm, thin;
petiole (0.5–)1–8 cm;
blade oblanceolate to elliptic, margins irregularly pinnatifid, sometimes subentire, apex acute to obtuse or rounded.
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.
erect.
1–4 opening per day near sunset, without noticeable scent;
buds with subequal free tips 2–7 mm;
floral tube (20–)28–95(–138) mm;
sepals (6–)10–30(–35) mm;
petals pale yellow, fading pale orange, drying lavender, (10–)12–30(–38) mm;
filaments (5–)8–15(–18) mm, anthers (3.5–)4–11 mm;
style (3.4–)4.2–11.5(–16.3) mm, stigma usually surrounded by anthers, sometimes (especially in some Texas populations) exserted beyond anthers.
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.
woody in age, rhombic-obovoid, winged, wings broadly triangular, 5–10 mm wide, often terminating in a hooked tooth, (10–)15–25(–28) × 4–8 mm (excluding wings), valve surface reticulate, dehiscent 1/8–1/3 their length.
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.
asymmetrically cuneiform, (2.1–)2.5–3(–3.3) mm.
narrowly obovoid, 0.5–0.9 × 0.3–0.5 mm.
= 14.
= 14.
Oenothera triloba
Oenothera rosea
Oenotheratriloba is primarily a species of the high plains from eastern Socorro County, New Mexico, east through all but eastern Texas, Oklahoma, to southern Kansas, east of Meade and Pawnee counties and south of Douglas and Saline counties. It becomes more sporadic eastward into Missouri south of the Missouri River, northwestern and north-central Arkansas, central and eastern Tennessee, northern Alabama, and Logan and Warren counties, Kentucky; also known from disjunct sites in northern Mexico from Nuevo León, Chihuahua, and Baja California, Mexico; and, introduced in Illinois, Indiana, Ohio, Kentucky (Campbell and Fayette counties), Pennsylvania, Virginia, Maryland, and the District of Columbia. Areas where it was introduced are represented by old collections; no current information indicates their continued presence in any of these areas. It was recently collected in Baca County, Colorado.
Capsules of dead plants sometimes form pineconelike clusters of ten to 100 or more capsules.
The illegitimate names Lavauxia nuttalliana Spach and L. triloba (Nuttall) Spach var. watsonii Britton pertain here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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