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Engelmann's evening-primrose

Habit Herbs winter-annual, conspicuously villous throughout, also strigillose on leaves and distal parts; from a taproot.
Stems

erect, unbranched or with few, spreading branches, 30–50(–80) cm.

Leaves

in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, (1–)2–6(–8) × 1–2(–3) cm;

sessile;

blade lanceolate to oblong lanceolate, proximal ones sometimes oblanceolate, margins coarsely repand-dentate or -pinnatifid.

Flowers

1–several opening per day near sunset;

buds nodding, weakly quadrangular, without free tips;

floral tube 20–30 mm;

sepals 13–21 mm, not spotted or with scattered small, maroon spots;

petals white, fading pink, broadly obovate or obcordate, 15–30 mm;

filaments 14–16 mm, anthers 6–8 mm;

style 40–50 mm, stigma exserted beyond anthers at anthesis.

Capsules

widely spreading, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering gradually from base to apex, 30–60 × 2–3 mm;

sessile.

Seeds

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

2n

= 14.

Oenothera engelmannii

Phenology Flowering Apr–Aug(–Sep).
Habitat Sandy prairies, dunes, disturbed areas, roadsides.
Elevation 500–1300 m. (1600–4300 ft.)
Distribution
from FNA
CO; KS; NM; OK; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenothera engelmannii is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). It has a relatively narrow distribution in sandy areas of eastern New Mexico and western Texas, extending to southeastern Colorado, western Oklahoma, and southwestern Kansas. The flower size seems to vary, with larger flowers in eastern New Mexico and considerably smaller flowers in the eastern part of its range.

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

Source FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra
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. elata, 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
Synonyms Anogra pallida var. engelmannii, A. engelmannii
Name authority (Small) Munz: Amer. J. Bot. 18: 316. (1931) — (as engelmanni)
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