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threadleaf evening-primrose, threadleaf sundrop

fourwing evening-primrose

Habit Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. Herbs annual or perennial, strigillose and also hirsute; from a slender taproot.
Stems

unbranched or with many ascending branches arising near base, erect, 10–50 cm.

15–50 cm.

Leaves

in a basal rosette and cauline, basal 1–2(–4) × 0.2–0.6 cm, petiole 0.2–1(–1.5) cm, blade ovate to obovate or narrowly elliptic;

cauline 1–4 × less than 0.1 cm, sessile, blade linear or filiform.

2.5–10 × 0.6–2.5 cm;

petiole 0.2–2.2 cm;

blade usually lanceolate to oblanceolate, sometimes elliptic, margins weakly serrate to sinuate-pinnatifid.

Flowers

usually 1–3 opening per day near sunrise;

buds without free tips;

sepals 1.5–2 mm;

petals bright yellow, fading pink, obcordate to obovate, 3–5(–7) mm;

filaments 1–2 mm, anthers 0.5–1 mm;

style 1–2 mm, stigma surrounded by anthers at anthesis.

1–3 opening per day near sunset;

buds with free tips 0.5–3 mm;

floral tube 10–30 mm;

sepals 20–40 mm;

petals white, fading pink, 20–43 mm;

filaments 12–18 mm, anthers 5–10 mm, pollen 85–100% fertile;

style 19–67 mm, stigma exserted beyond anthers at anthesis.

Capsules

ellipsoid-rhombic to subglobose, 4-angled, 4–6(–10) × 1.5–3 mm, stipe 0–4 mm, valve midrib raised at distal end, indehiscent or tardily dehiscent distally;

sessile.

broadly clavate or obovoid, 20–51 × 5–7 mm, winged, wings 2–4 mm, valve surface with prominent midrib, proximal stipe 8–45 mm;

sessile.

Seeds

clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm.

narrowly obovoid, 1–1.5 × 0.5–0.7 mm.

2n

= 14.

= 14.

Oenothera linifolia

Oenothera tetraptera

Phenology Flowering Apr–Jun(–Aug). Flowering Feb–May.
Habitat Prairies, open woodlands, open rocky and sandy sites, roadsides. Alluvial flats, open areas, sandy soil, weedy sites.
Elevation 0–400 m. (0–1300 ft.) 10–300[–2000] m. (0–1000[–6600] ft.)
Distribution
from FNA
AL; AR; FL; GA; IL; KS; KY; LA; MO; MS; NC; OK; SC; TN; TX
[WildflowerSearch map]
[BONAP county map]
from FNA
TX; Mexico; Central America; West Indies (Jamaica); n South America [Introduced widely in temperate Europe, Asia, s Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Kneiffia linearifolia Spach (1835) is an illegitimate name based on Oenothera linifolia.

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

In the flora area, Oenothera tetraptera is known only from southern Texas. Oenothera tetraptera presumably has become naturalized in South America (Argentina, Bolivia, Colombia, Ecuador, Venezuela), West Indies (Jamaica), Europe, Asia, South Africa, and Australia.

Oenothera candida Dumont Courset is a superfluous name, as is O. candida Bellardi ex Colla, and they both pertain here. The name Hartmannia macrantha Spach is illegitimate and pertains here.

(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. Peniophyllum Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Leucocoryne
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. 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. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
Synonyms Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium Hartmannia latiflora, H. tetraptera, O. latiflora, O. tetraptera var. immutabilis, Xylopleurum tetrapterum
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) Cavanilles: Icon. 3: 40, plate 279. (1796)
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