The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

evening primrose, Hooker's evening-primrose, western evening primrose

Habit Herbs biennial or short-lived perennial, densely strigillose and either sparsely or moderately villous, with appressed or spreading hairs (sometimes with red-pustulate bases), distally sometimes also glandular puberulent. Herbs perennial, densely strigillose throughout, sometimes glandular puberulent distally; from a stout taproot.
Stems

erect, green, flushed with red proximally or red throughout, unbranched or branches obliquely arising from rosette and secondary branches arising from main stem, 30–250 cm.

several to many, decumbent to ascending, branched, 4–20(–30) cm.

Leaves

in a basal rosette and cauline, basal 10–43 × 1.2–4(–6) cm, cauline 4–25 × 1–2.5(–4) cm;

blade dull green to grayish green, rarely red, narrowly oblanceolate or oblanceolate to narrowly elliptic or narrowly lanceolate, margins usually flat, rarely undulate, bluntly dentate or subentire, teeth sometimes widely spaced, proximal blades sometimes sinuate-dentate toward base;

bracts persistent.

0.6–5 × 0.08–0.6 cm, fascicles of small leaves 0.2–1 cm often present in non-flowering axils;

petiole 0 cm;

blade narrowly lanceolate or narrowly oblanceolate, base attenuate to truncate, sometimes clasping, margins entire or subentire, sometimes revolute, sometimes weakly undulate, apex acute to obtuse.

Inflorescences

erect, unbranched.

Flowers

opening near sunset;

buds erect, 6–10 mm diam., with free tips terminal, erect, 1–7 mm;

floral tube (20–)30–45(–50) mm;

sepals yellowish green, red-striped or strongly flushed with red, 27–50 mm;

petals yellow to pale yellow, fading orange or pale yellow, very broadly obcordate, (25–)30–47(–55) mm;

filaments 17–25 mm, anthers 8–23 mm, pollen 90–100% fertile;

style 50–90 mm, stigma exserted beyond anthers at anthesis.

usually 1 per stem opening per day near sunset;

buds with free tips 0.3–3 mm;

floral tube 25–60 mm, funnelform in distal 1/2 or less;

sepals 8–20 mm;

petals yellow, fading pale pink or pale purple, 12–28 mm;

filaments 6–12 mm, anthers 5–11 mm, pollen 85–100% fertile;

style 30–75 mm, stigma yellow, quadrangular, usually exserted beyond anthers.

Capsules

erect or slightly spreading, dull green or gray-green when dry, narrowly lanceoloid, 20–65 × 4–7 mm, free tips of valves 0.5–2.5 mm.

6–25 × 1–3 mm, hard, promptly dehiscent throughout their length.

Seeds

1–1.9 × 0.6–1.2 mm.

obovoid, 1.5–2.5 mm.

2n

= 14.

Oenothera elata

Oenothera lavandulifolia

Phenology Flowering Apr–Aug.
Habitat Local and sparse, on sandy and rocky, calcareous soil, high plains, mountains, often with Artemisia tridentata, Cercocarpus, Juniperus, Pinus edulis, or P. monophylla, sometimes in lower zones with Larrea, or in higher zones with P. ponderosa.
Elevation 600–2800 m. (2000–9200 ft.)
Distribution
from USDA
w United States; c United States; Mexico; Central America
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; KS; NE; NM; OK; SD; TX; WY; Mexico (Nuevo León)
[BONAP county map]
Discussion

Subspecies 3 (2 in the flora).

Subspecies elata differs in anthers 7–12 mm, fewer or no pustulate-based hairs, and generally smaller flowers and habit. It ranges from the highlands of central Mexico, including Guanajuato, Hidalgo, México, Michoacán, Puebla, Querétaro, and Veracruz, south to Guatemala, El Salvador, Costa Rica, and Panama.

Oenothera elata has plastome I and a AA genome composition. Onagra kunthiana Spach is a superfluous name that pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Oenothera lavandulifolia is known from southern Fall River County, South Dakota, southeastern Wyoming, and far western Nebraska, through western Kansas, Colorado, eastern and southern Utah, northwestern Oklahoma, and the Texas Panhandle to trans-Pecos Texas, central New Mexico, northern and central Arizona, and eastern Nevada. It also occurs in Nuevo León, Mexico, and may be more widespread in northern Mexico. H. F. Towner (1977) found that O. lavandulifolia is self-incompatible and vespertine.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Plants strigillose, usually also villous, with appressed or spreading hairs, sometimes these with red-pustulate bases, distally sometimes also glandular puberulent; buds green to yellowish green, red-striped, or sometimes red throughout; anthers 8–15(–20) mm.
subsp. hirsutissima
1. Plants strigillose, also villous with appressed or spreading hairs, usually these with conspicuous red-pustulate bases, also glandular puberulent; buds flushed with red; anthers 12–23 mm.
subsp. hookeri
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Oenothera Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Salpingia
Sibling taxa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
Subordinate taxa
O. elata subsp. hirsutissima, O. elata subsp. hookeri
Synonyms Calylophus hartwegii subsp. lavandulifolius, C. hartwegii var. lavandulifolius, C. lavandulifolius, Galpinsia lavandulifolia, G. lavandulifolia var. glandulosa, O. hartwegii var. lavandulifolia, O. lavandulifolia var. glandulosa
Name authority Kunth in A. von Humboldt et al.: Nov. Gen. Sp. 6(fol.): 72; 6(qto.): 90. (1823) Torrey & A. Gray: Fl. N. Amer. 1: 501. (1840) — (as lavandulaefolia)
Web links