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long evening primrose, long-stem evening-primrose

Habit Herbs biennial or short-lived perennial, sparsely strigillose, sometimes also villous and with pustulate hairs near inflorescence, sometimes also glandular puberulent.
Stems

erect, usually flushed with red proximally or sometimes green, unbranched or with branches obliquely arising from base, secondary branches arising from main stem, 60–300 cm.

Leaves

in a basal rosette and cauline, basal 9–40 × 1.4–5 cm, cauline 5–22 × 0.8–2.5 cm;

blade dull green, flat, narrowly oblanceolate, oblanceolate to narrowly elliptic, or narrowly lanceolate, margins bluntly dentate or subentire, teeth widely spaced;

bracts persistent.

Inflorescences

open, erect, unbranched.

Flowers

opening near sunset;

buds erect, 5–9 mm diam., with free tips terminal, erect, 2–6 mm;

floral tube deciduous after anthesis, 60–135 mm;

sepals yellowish green, flushed with some red or red to dark red throughout, 25–55 mm;

petals yellow to pale yellow, fading orange or pale yellow, very broadly obcordate, 28–65 mm;

filaments 20–40 mm, anthers 14–20 mm, pollen 90–100% fertile;

style 90–180 mm, stigma exserted beyond anthers at anthesis.

Capsules

erect or slightly spreading, dull green or gray-green when dry, narrowly lanceoloid, 25–55 × 4–9 mm, free tips of valves 1–2(–3) mm.

Seeds

1–1.9 × 0.6–1.2 mm.

2n

= 14.

Oenothera longissima

Phenology Flowering Jul–Sep(–Oct).
Habitat Seasonally moist sites, sandy or sandy-loam soil, sites with high alkalinity or associated with limestone, along desert washes, streams, seeps, roadsides.
Elevation 800–2800 m. (2600–9200 ft.)
Distribution
from FNA
AZ; CA; CO; NM; NV; UT
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenothera longissima has plastome I and a AA genome composition.

Oenothera longissima is known from northern and western Arizona, Inyo, Los Angeles, and San Bernardino counties in California, Delta and Montezuma counties in Colorado, eastern Nevada, San Juan County in New Mexico, and southern Utah.

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

Source FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Oenothera
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. 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. 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. clutei, O. longissima subsp. clutei, O. longissima var. clutei
Name authority Rydberg: Bull. Torrey Bot. Club 40: 65. (1913)
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