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threadleaf evening-primrose, threadleaf sundrop

high-plains beeblossom, woolly beeblossom

Habit Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. Herbs suffrutescent, densely soft-villous, hairs mostly appressed, 2–3 mm, becoming less villous distally, also strigillose, rarely glandular puberulent or hispidulous, plant parts grayish green; from deep, twisted, woody rootstock.
Stems

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

erect, several-branched near ground, also branched proximal to inflorescences, 60–280 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, 0.5–8 × 0.15–2 cm, sessile, blade narrowly lanceolate or oblanceolate to very narrowly elliptic or linear, margins usually subentire or shallowly sinuate-dentate, sometimes deeply sinuate-dentate, often undulate.

Inflorescences

slender.

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 1.5–5 mm;

sepals 6–14 mm;

petals white, fading pink to red, slightly unequal, elliptic, 7–13 mm, clawed;

stamens presented in lower 1/2 of flower, filaments 4.5–11 mm, anthers 2–4.5 mm, pollen 90–100% fertile;

style 9–19 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.

lanceoloid to narrowly ovoid, 4-winged, 9–19 × 1–3.5 mm, abruptly constricted to a long, sterile stipe 2–10 mm.

Seeds

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

(1 or)2–4, 2–3(–4) × 0.8–1.3 mm, yellowish to light brown or rarely reddish brown.

2n

= 14.

Oenothera linifolia

Oenothera cinerea

Phenology Flowering Apr–Jun(–Aug).
Habitat Prairies, open woodlands, open rocky and sandy sites, roadsides.
Elevation 0–400 m. (0–1300 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 USDA
sc United States
[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.)

Subspecies 2 (2 in the flora).

P. H. Raven and D. P. Gregory (1972[1973]) determined Oenothera cinerea to be self-incompatible. The two subspecies recognized here have disjunct distributions but are very similar morphologically.

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

Key
1. Herbs soft-villous, also strigillose or glandular puberulent.
subsp. cinerea
1. Herbs soft-villous, also hispidulous.
subsp. parksii
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. 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. cinerea subsp. cinerea, O. cinerea subsp. parksii
Synonyms Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium Gaura cinerea
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) (Wooton & Standley) W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 211. (2007)
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