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Photo is of parent taxon
Habit Herbs perennial (short-lived or, sometimes, suffrutescent) or annual, glabrous or strigillose; from a stout taproot. Herbs perennial.Stems several–many, decumbent to ascending, moderately branched, (10–)25–40 cm.
Stems

1–many, weakly decumbent to ascending or erect, unbranched to moderately branched, (10–)25–80 cm.

Leaves

1–9 × (0.1–)0.3–1 cm, sometimes fascicles of small leaves to 2 cm present in non-flowering axils;

petiole 0–0.6 cm;

blade linear to narrowly lanceolate or oblanceolate, often folded lengthwise, usually not much reduced distally, proximalmost leaves sometimes spatulate, base attenuate, margins subentire or serrulate or spinulose-serrate, apex acute.

1–4 × (0.1–)0.3–0.6 cm;

blade margins subentire or serrate, sometimes weakly undulate.

Flowers

opening at sunrise;

buds with free tips 0–4 mm;

floral tube 5–20 mm;

sepals 4–12 mm, midribs keeled;

petals yellow, fading orangish to purplish, 6–25 mm; antisepalous filaments 2–8 mm, antipetalous filaments 1–4 mm, anthers 2–7 mm, pollen 90–100% fertile;

style 9–30 mm, stigma sometimes blue-black, discoid to quadrangular, exserted beyond anthers.

buds with free tips 0–2 mm;

sepals often with slightly keeled midribs.

Capsules

10–35 × 1–2 mm, hard, dehiscent 1/2 their length, often tardily dehiscent throughout their length.

Seeds

obovoid, 1–1.8 mm, sharply angled, apex truncate.

2n

= 14.

Oenothera capillifolia

Oenothera capillifolia subsp. berlandieri

Phenology Flowering Mar–Sep.
Habitat Grassy prairies, plains, low hills, sandy, gravelly, and limestone soil, relatively dry areas, in vegetation dominated by mesquite, oaks, and Opuntia.
Elevation 0–1200 m. (0–3900 ft.)
Distribution
c United States; sc United States; n Mexico
from FNA
KS; NM; OK; TX; Mexico (Coahuila, Nuevo León)
Discussion

Subspecies 2 (2 in the flora).

Oenothera capillifolia is self-incompatible (H. F. Towner 1977).

Oenothera berlandieri (Spach) Steudel 1841, not D. Dietrich 1840, is superfluous and cannot be used in Oenothera when transferred from Calylophus, and pertains here.

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

Subspecies berlandieri occurs in Meade, Reno, and Seward counties in Kansas, south through eastern New Mexico, the Texas Panhandle, and western Oklahoma to Crane, Culberson, and Ward counties in Texas, southeastward to near the Pecos and Rio Grande rivers to the Gulf Coast, becoming widespread on the Coastal Plain north to Milam County in Texas; it also occurs in the Santa Rosa Mountains of northern Coahuila, Mexico.

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

Key
1. Stems 1–several, ascending to erect, 30–80 cm; leaves 2.5–9 cm.
subsp. capillifolia
1. Stems several–many, decumbent to ascending, (10–)25–40 cm; leaves 1–4 cm.
subsp. berlandieri
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Calylophus Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Calylophus > Oenothera capillifolia
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. 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. capillifolia subsp. capillifolia
Subordinate taxa
O. capillifolia subsp. berlandieri, O. capillifolia subsp. capillifolia
Synonyms Meriolix capillifolia Calylophus berlandieri, C. drummondianus subsp. berlandieri, Meriolix berlandieri
Name authority Scheele: Linnaea 21: 576. (1848) (Spach) W. L. Wagner & Hoch: PhytoKeys 28: 71. (2013)
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