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threadleaf evening-primrose, threadleaf sundrop

slenderstalk beeblossom

Habit Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. Herbs perennial, clumped, sparsely to densely strigillose, inflorescence usually glabrous or glandular puberulent, sometimes proximalmost parts villous, hairs erect, 1–2 mm; from heavy, twisted, woody rootstock.
Stems

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

erect, branched below and just above ground, branched also proximal to inflorescences, 60–250(–300) 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.

in a basal rosette and cauline, (1–)3–9 × (0.1–)0.5–1.3 cm, blade linear or narrowly lanceolate to narrowly oblanceolate, margins slightly to coarsely sinuate-dentate.

Inflorescences

slender, often well-branched, buds small and well-spaced.

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.

4-merous, zygomorphic, opening near sunset;

floral tube 2.5–6 mm;

sepals 5–12.5 mm;

petals white, fading pink to red, slightly unequal, elliptic, 5–10 mm, clawed;

stamens presented evenly around flower parts, filaments 3–8.5 mm, anthers 1.4–4 mm, pollen 90–100% fertile;

style 8.5–19 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.

ovoid, narrowly 4-winged or 4-angled, 5–10 × 1.5–2 mm, abruptly constricted to a sterile stipe 0.5–4.5 mm.

Seeds

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

1 or 2, yellowish to reddish brown, 1.5–3.5 × 1–1.5 mm.

2n

= 14.

= 14.

Oenothera linifolia

Oenothera filipes

Phenology Flowering Apr–Jun(–Aug). Flowering May–Sep(–Oct).
Habitat Prairies, open woodlands, open rocky and sandy sites, roadsides. Sandy hills and flats, open woods.
Elevation 0–400 m. (0–1300 ft.) 0–300 m. (0–1000 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
AL; FL; GA; IL; IN; KY; LA; MO; MS; SC; TN
[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 filipes occurs marginally in several states, including: southernmost Illinois and southern Indiana; northern Florida; southeastern Mississippi; and, Washington Parish, Louisiana. P. H. Raven and D. P. Gregory (1972[1973]) determined O. filipes to be self-incompatible.

(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. Gaura > subsect. Stipogaura
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. 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
Synonyms Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium Gaura filipes, G. filipes var. major, G. michauxii
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) (Spach) W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 212. (2007)
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