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El Paso evening primrose

Habit Herbs acaulescent or caulescent, densely strigillose and glandular puberulent distally; from a taproot. Herbs perennial, densely strigillose, glabrate proximally; from fibrous roots.
Stems

densely leafy, 4–20 cm.

ascending, unbranched to few-branched, 30–65 cm.

Leaves

in a basal rosette, sometimes also cauline, 5–16 × (0.2–)0.3–0.5(–0.7) cm;

petiole 0.6–3.5 cm;

blade linear to narrowly lanceolate, margins entire or sometimes proximal 1/2 of blade remotely lobed, apex long-attenuate, acute to rounded.

in a basal rosette and cauline, basal 2.5–7 ×0.7–2.3 cm, petiole 1–1.5 cm, blade oblanceolate, margins subentire, undulate;

cauline (3–)6–7(–9) ×(0.3–)0.6–0.8(–1.1) cm, sessile, blade lanceolate to narrowly lanceolate, margins subentire.

Inflorescences

nodding, flowers in axils of distalmost few nodes.

Flowers

usually 1–3, rarely more, opening per day near sunset, weakly scented;

buds with unequal free tips 0.7–1.2 mm;

floral tube (55–)75–100(–125) mm;

sepals 34–40 mm;

petals lemon-yellow, fading orange, drying lavender to purple, broadly obovate, 35–43 mm, sometimes with terminal tooth;

filaments 17–25 mm, anthers 14–17 mm;

style (85–)105–135(–143) mm, stigma exserted beyond anthers at anthesis.

opening near sunrise;

buds with free tips 1–2 mm, connivent to spreading;

floral tube 10–15(–20) mm;

sepals 10–18 mm;

petals bright yellow, fading pale pink, 15–25 mm;

filaments 7–9 mm, anthers 5–8 mm, pollen 85–100% fertile;

style 10–12 mm, stigma exserted beyond anthers at anthesis.

Capsules

leathery, lanceoloid to ovoid, winged, wings 4–6 mm wide, body 25–30 × 8 mm, dehiscent 1/4–1/3 their length;

pedicel 1–2(–3) mm.

ellipsoid, 4-angled, 8–10 × 3–4 mm, stipe 0–2 mm;

sessile.

Seeds

numerous, usually in 2 distinct rows per locule, often reduced to 1 row near apex, rarely 1 row throughout, obovoid to subcuboid, 2.5–4 × 2.5–3.5 mm.

1 × 0.5 mm.

2n

= 42.

= 56.

Oenothera coryi

Oenothera sessilis

Phenology Flowering Apr–May. Flowering May–Jun.
Habitat Open grasslands, disturbed areas. Moist remnant prairies in sandy or silty soil.
Elevation 300–1000 m. (1000–3300 ft.) 0–100 m. (0–300 ft.)
Distribution
from FNA
TX
[BONAP county map]
from FNA
AR; LA; TX
Discussion

Oenothera coryi is known only from Baylor, Callahan, Knox, Nolan, Taylor, and Throckmorton counties in north-central Texas and Crosby and Garza counties in the Texas Panhandle.

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

Oenothera sessilis is relatively rare within its range and has a narrow overall distribution, occurring in Ashley, Phillips, Prairie, and St. Francis counties in Arkansas, Allen, Claiborne, and Tensas parishes in Louisiana, and Galveston County in Texas. Oenothera sessilis appears to be relatively rare and may no longer occur in Texas; it was last collected there in the 1840s by Lindheimer on Galveston Island. It is also rare in Louisiana but has been collected in recent decades. It is currently most common in Arkansas. P. A. Munz (1937, 1965) treated this taxon as O. sessilis, but G. B. Straley (1977) in his revision of sect. Kneiffia placed it as a subspecies of O. pilosella based on a common octoploid (2n = 56) chromosome number, morphology, and field studies. K. N. Krakos et al. (2014), based on new field studies, controlled greenhouse breeding experiments, and phylogenetic data found that this taxon differs morphologically from O. pilosella by having consistently shorter stature and smaller flowers, is self-compatible, and does not form a monophyletic group with O. pilosella in molecular analyses, and is here reinstated as a distinct species.

Oenothera sessilis is in the Center for Plant Conservation’s National Collection of Endangered Plants as O. pilosella subsp. sessilis.

(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. Megapterium Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kneiffia
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. 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. 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. 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 Kneiffia sessilis, O. pilosella subsp. sessilis, O. pilosella var. sessilis
Name authority W. L. Wagner: Ann. Missouri Bot. Gard. 73: 475. (1986) (Pennell) Munz: Bull. Torrey Bot. Club 64: 291. (1937)
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