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

California evening primrose

Nuttall's evening primrose

Habit Herbs winter-annual, younger parts sparsely to densely strigillose and sparsely to densely hirsute, older stems glabrate; from a taproot. 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

ascending to erect, with decumbent branches, thickened at base, tapering toward apex, 10–35(–60) cm.

erect, often branched, 30–100 cm.

Leaves

in a basal rosette and cauline, basal 5–10(–26) × 0.6–1.5(–3.5) cm, cauline 5–8(–15.5) × 1–2 cm;

petiole 0–12 cm;

blade lanceolate to oblanceolate, margins pinnatifid or sometimes coarsely serrate.

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.

Flowers

1–several opening per day near sunset;

buds nodding, weakly quadrangular, without free tips;

floral tube 26–31 mm;

sepals 19–26 mm, conspicuously maroon-spotted, each spot at base of a long hair;

petals white, fading pink to deep pink, broadly obovate or obcordate, 16–26(–36) mm;

filaments 9–15 mm, anthers 7–9 mm;

style 45–50 mm, stigma exserted beyond anthers at anthesis.

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.

Capsules

spreading, woody in age, curved upward, or distal end recurved, cylindrical, obtusely 4-angled, especially toward base, tapering gradually from base to apex, 30–80 × 2.5–3.5 mm;

sessile.

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.

Seeds

numerous, in 1 row per locule, light brown to yellowish brown with dark purple splotches, obovoid, 1.6–2 mm.

numerous, in 1 row per locule, reddish dark brown, narrowly obovoid, 1.5–2.3 mm.

2n

= 14.

= 14, 28.

Oenothera arizonica

Oenothera nuttallii

Phenology Flowering (Oct–)Feb–May. Flowering Jun–Sep.
Habitat Gravelly or sandy soil, along watercourses, disturbed sites. Dry, sandy or rocky prairies, open wooded hillsides, disturbed areas, roadsides.
Elevation 200–1400 m. (700–4600 ft.) 500–2200(–2900) m. (1600–7200(–9500) ft.)
Distribution
from FNA
AZ; Mexico (Sonora)
[BONAP county map]
from FNA
CO; IL; MI; MN; MT; ND; NE; SD; WI; WY; AB; MB; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenothera arizonica occurs in southern Arizona from Maricopa and Yuma counties to Cochise County, and from scattered localities in northern Sonora, Mexico, including Cerro Tepopa, Puerto Libertad, and Tastiota. The populations from southwestern Arizona (Yuma County) southward to Sonora often grow on low dunes.

Populations from sand dunes in Yuma County, Cabeza Prieta National Wildlife Refuge, appear to be a large phenotype of Oenothera arizonica that differ from all other specimens in the size of vegetative parts and flowers, and comprise all of the atypical measurements given in the description. Oenothera arizonica typically grows on dunes in Sonora, but rarely so in Arizona. Populations growing on dunes should be studied further and compared to non-dune populations in the northern and eastern portion of the range. Oenothera arizonica is self-compatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010).

(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.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra
Sibling taxa
O. acutissima, O. albicaulis, O. argillicola, O. arida, 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. 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. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, 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
Synonyms O. deltoides var. arizonica, O. avita subsp. arizonica, O. californica subsp. arizonica O. albicaulis, O. albicaulis var. nuttallii
Name authority (Munz) W. L. Wagner: Novon 8: 308. (1998) Sweet: Hort. Brit. ed. 2, 199. (1830)
Web links