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flaming Gorge evening primrose

Habit Herbs perennial, subacaulescent or very short-caulescent, strigillose mostly along leaf margins and flower parts, also sparsely glandular puberulent, sometimes also sparsely hirsute distally; from a stout taproot, usually with several long, lateral roots often producing adventitious shoots. Herbs perennial, spreading by rhizomes (forming colonies), strigillose, often also villous; from taproot.
Stems

(when present) ascending, (1–)several–10, densely leafy, 1–2 cm.

ascending to decumbent, several-branched from base, usually also irregularly branched distally, sometimes with a single, unbranched stem, 20–60(–120) cm.

Leaves

primarily in a basal rosette, 7–14(–18) × (0.3–)0.5–1(–1.5) cm, moderately thick and stiff;

petiole (1.2–)3–5 cm;

blade linear to very narrowly elliptic, margins irregularly and coarsely dentate or pinnately lobed, apex long-attenuate.

in a basal rosette and cauline, 0.5–7.5(–9.5) × 0.1–2.2 cm, blade narrowly lanceolate to elliptic, margins subentire or shallowly sinuate-dentate.

Flowers

1–3 opening per day near sunset;

buds with unequal free tips 1–3 mm;

floral tube (53–)60–100 mm;

sepals 26–50 mm;

petals bright yellow, fading deep reddish orange, drying purplish brown, 28–50 mm;

filaments 21–35 mm, anthers 9–11 mm;

style 75–143 mm, stigma exserted beyond anthers.

4-merous, zygomorphic, opening near sunset;

floral tube 4–14 mm;

sepals 7–11(–14) mm;

petals white, fading red, slightly unequal, elliptic, 6–10 mm, clawed;

filaments 4–8.5 mm, anthers 3–6 mm, pollen 90–100% fertile;

style 12–26 mm, stigma exserted beyond anthers at anthesis.

Capsules

leathery in age, oblong-oblanceoloid, narrowly winged, wings oblong, 1–2(–4) mm wide, broadest near apex, 14–18(–22) × 7–8 mm (excluding wings), apex abruptly constricted, dehiscent 1/4–1/3 their length, valve surface with inconspicuous veins;

sessile.

erect, pyramidal in distal 1/2, conspicuously bulging at base of distal pyramidal part, strongly 4-angled, conspicuously bulging at base, abruptly constricted to terete proximal part, 7–13 × 3–5 mm;

sessile.

Seeds

asymmetrically cuneiform, 2–2.5 mm.

(2 or)3 or 4(–8), reddish brown, 2–2.5 × 1–1.3 mm.

2n

= 14.

= 28.

Oenothera acutissima

Oenothera hispida

Phenology Flowering May–Jun. Flowering May–Jul(–Nov).
Habitat Restricted to sandy and gravelly, reddish, soil in seasonally wet sites, meadows, depressions, along arroyos, among rocks, in mixed conifer forests, sagebrush scrub. Sandy loam.
Elevation 1800–2400(–2600) m. (5900–7900(–8500) ft.) 60–1900 m. (200–6200 ft.)
Distribution
from FNA
CO; UT
[BONAP county map]
from FNA
AR; CA; GA; TX; c Mexico
Discussion

Oenothera acutissima is known only from the vicinity of Manila, eastern Uinta Mountains, Daggett and Duchesne counties, Utah, east to areas in and near the foothills of the Douglas and Blue mountains, in Uinta County, Utah, and Moffat County, Colorado.

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

Oenothera hispida is native across the eastern half of Texas, south through Mexico to Oaxaca and Puebla; it is naturalized in Sevier County, Arkansas, coastal southern California, and Glynn County Georgia.

P. H. Raven and D. P. Gregory (1972[1973]) reported Oenothera hispida to be self-incompatible. It occasionally forms hybrids with O. suffrutescens.

(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. Lavauxia > subsect. Lavauxia Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Gaura > subsect. Xenogaura
Sibling taxa
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. 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. 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 O. flava var. acutissima Gaura hispida, G. crispa, G. drummondii, G. roemeriana, O. xenogaura, Schizocarya crispa, S. drummondii
Name authority W. L. Wagner: Syst. Bot. 6: 153, fig. 1. (1981) (Bentham) W. L. Wagner, Hoch & Zarucchi: PhytoKeys 50: 26. (2015)
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