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threadleaf evening-primrose, threadleaf sundrop

Kunth's evening-primrose

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

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

5–40 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.

1–6 × 0.3–3 cm;

petiole 0.1–1.1 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 0–0.5 mm;

floral tube 5–31 mm;

sepals 10–27 mm;

petals white, fading pink, 8–25 mm;

filaments 6–12 mm, anthers 3–5 mm, pollen 35–65% fertile;

style 12–30 mm, stigma surrounded by 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, 7–31 ×3–5 mm, winged, wings 0.5–1.5 mm, valve surface with prominent midrib, proximal stipe 3–17 mm;

sessile.

Seeds

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

narrowly obovoid, 0.9–1.2 × 0.4–0.5 mm.

2n

= 14.

= 14.

Oenothera linifolia

Oenothera kunthiana

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.) 10–1300[–2000] m. (0–4300[–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; n South America [Introduced widely in temperate Europe, Asia, Pacific Islands (Hawaii), 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.)

Oenothera kunthiana is a PTH species and forms a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous, common and widespread from sea level to middle elevations in the mountains from southern Texas south throughout Mexico except for Baja California and the tropical lowlands southward to Guatemala, Nicaragua, and Costa Rica; it was once collected in Minas Gerais, Brazil. Oenothera kunthiana was recently found to be naturalized in the Hawaiian Islands.

Oenothera pinnatifida Kunth is a later homonym of O. pinnatifida Nuttall and another later homonym is O. micrantha Walpers, not Hornemann ex Sprengel (1825); they both pertain 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. 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
Synonyms Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium Hartmannia kunthiana, H. domingensis, H. parviflora, O. domingensis, O. fissifolia, O. walpersii
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) (Spach) Munz: Amer. J. Bot. 19: 759. (1932)
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