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Texas evening primrose

Habit Herbs perennial, caulescent, strigillose and also sparsely hirsute; from slender taproot. Herbs perennial (short-lived or, sometimes, suffrutescent) or annual, glabrous or strigillose; from a stout taproot.
Stems

several–many, ascending, unbranched or branched, 25–50 cm.

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

Leaves

in a basal rosette and cauline, basal (1–)2.5–6.5 × 0.6–2.3 cm, blade narrowly elliptic to narrowly ovate or ovate, margins weakly serrulate to sinuate-pinnatifid;

cauline 1–5.5 × 0.6–2 cm, blade narrowly elliptic to narrowly ovate, margins weakly serrulate.

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.

Inflorescences

erect.

Flowers

1–3 opening per day near sunrise;

buds with free tips 0–1 mm;

floral tube 15–26 mm;

sepals 15–23 mm;

petals rose purple, fading darker, 12–25(–30) mm;

filaments 9–13 mm, anthers 3.5–6mm, pollen 85–100% fertile;

style 26–36 mm, stigma exserted beyond anthers at anthesis.

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.

Capsules

clavate or narrowly obovoid, 9–15 × 3.5–6 mm, apex attenuate to a sterile beak, valve midrib prominent in distal part, proximal stipe 7–12(–28) mm, gradually taperingto base;

sessile.

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

Seeds

narrowly obovoid, 0.8–1 × 0.2–0.4 mm.

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

2n

= 14.

Oenothera texensis

Oenothera capillifolia

Phenology Flowering May–Sep.
Habitat Sandy and gravel bars of streambeds and along streams.
Elevation 900–2500 m. (3000–8200 ft.)
Distribution
from FNA
TX; Mexico (Coahuila, Tamaulipas)
[BONAP county map]
c United States; sc United States; n Mexico
Discussion

In the flora area, Oenothera texensis is known only from Jeff Davis County.

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

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.)

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. Hartmannia Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Calylophus
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. 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. 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. 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
Subordinate taxa
O. capillifolia subsp. berlandieri, O. capillifolia subsp. capillifolia
Synonyms Meriolix capillifolia
Name authority P. H. Raven & D. R. Parnell: Madroño 20: 247. (1970) Scheele: Linnaea 21: 576. (1848)
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