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Oakes' evening-primrose

little evening-primrose, perennial evening-primrose, perennial sundrops, small sundrops

Habit Herbs biennial, densely silky-strigillose, at least proximally, also sparsely villous with long, appressed hairs, sometimes also villous with spreading, pustulate hairs and/or glandular puberulent distally. Herbs perennial, sparsely to moderately strigillose, glandular puberulent distally; from fibrous roots.
Stems

erect to decumbent, green or flushed with red on proximal parts or throughout, unbranched or bushy and branched from base, with side branches arising obliquely or arcuately from rosette, 10–60 cm.

usually erect to slightly decumbent, unbranched to few-branched distally, (3–)15–30(–75) cm.

Leaves

in a basal rosette and cauline, basal 8–30 × 0.5–3 cm, cauline 3.5–20 ×0.5–2.7 cm;

blade grayish green to dull green, very narrowly oblanceolate to narrowly oblanceolate or narrowly elliptic, margins flat, subentire or remotely dentate, teeth sometimes blunt, sometimes sinuate-dentate proximally;

bracts persistent.

in a basal rosette and cauline, basal 2–4 × 0.2–1.2 cm, petiole (0.2–)0.5–1.2(–2.5) cm, blade oblanceolate to obovate;

cauline 3–7 × 0.2–1.2 cm, petiole 0.1–1 cm, blade oblanceolate to obovate, margins entire or weakly and remotely denticulate.

Inflorescences

usually recurved with ascending tip distally, rarely suberect, unbranched.

nodding, flowers in axils of distalmost few nodes.

Flowers

opening near sunset;

buds erect, 3–5 mm diam., with free tips subterminal, spreading to erect, 2.5–4 mm;

floral tube 15–40 mm;

sepals green to yellow, flushed with red and dark red flecked or red-striped, 9–17 mm;

petals yellow to pale yellow, fading yellowish white to pale yellowish orange, very broadly obcordate, 7–20 mm;

filaments 6–15 mm, anthers 3–7 mm, pollen ca. 50% fertile;

style 20–45 mm, stigma surrounded by anthers at anthesis.

opening near sunrise, nearly unscented;

buds with free tips to 1 mm, connivent;

floral tube 3–10 mm;

sepals 2–4 mm;

petals bright yellow, fading pale yellow, or orangish yellow to pale pink, 5–10 mm;

filaments 3–4 mm, anthers 1–2 mm, pollen 40–70% fertile;

style 3–4 mm, stigma surrounded by anthers at anthesis.

Capsules

erect or slightly spreading, usually rusty brown when dry, narrowly lanceoloid to lanceoloid, 15–40 × 4–8 mm, free tips of valves 0.5 mm.

clavate, 4-angled or narrowly 4-winged, 5–10 × 2–3 mm, stipe 1–2 mm;

sessile.

Seeds

1.1–1.2 ×0.8–1 mm.

0.7–0.8 × 0.2–0.3 mm.

2n

= 14.

= 14.

Oenothera oakesiana

Oenothera perennis

Phenology Flowering Jun–Aug. Flowering May–Jul(–Aug).
Habitat Sandy coastal meadows and dunes, gravelly or rocky sites along rivers, disturbed sites, roadsides. Fields, open woods, boggy areas.
Elevation 0–50(–500) m. (0–200(–1600) ft.) (0–)150–900(–1400) m. ((0–)500–3000(–4600) ft.)
Distribution
from FNA
CT; DC; DE; IL; IN; MA; MD; ME; MI; MN; NH; NJ; NY; OH; PA; RI; VA; VT; WI; MB; NB; NF; NS; ON; PE; QC [Introduced in Europe, Asia]
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; DC; DE; IA; IL; IN; KY; MA; MD; ME; MI; MN; MO; NC; NE; NH; NY; OH; PA; RI; SC; TN; VA; VT; WI; WV; BC; MB; NB; NF; NS; ON; PE; QC; SPM
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenothera oakesiana is a PTH species and forms a ring of 14 chromosomes or a ring of 12 and 1 bivalent in meiosis, and is self-compatible and autogamous (W. Dietrich et al. 1997). It has plastome IV and a AC genome composition.

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

Oenothera perennis, a PTH species that forms a ring of 14 chromosomes in meiosis, is self-compatible and autogamous (G. B. Straley 1977). It is disjunct in Nebraska from the rest of its range in eastern North America, occurring in Garfield, Holt, and Rock counties (R. Kaul, pers. comm.). It is introduced in British Columbia.

Oenotherapumila Linnaeus is an illegitimate substitution based on O. perennis Linnaeus, while Kneiffia michauxii Spach is an illegitimate substitution based O. pumila, as is K. pumila Spach, and the three 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. Oenothera > subsect. Oenothera Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kneiffia
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. 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. 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 O. biennis var. oakesiana, O. ammophila, O. ammophiloides, O. ammophiloides var. angustifolia, O. ammophiloides var. laurensis, O. atrovirens var. ostreae, O. canovirens var. cymatilis, O. cruciata var. stenopetala, O. cymatilis, O. deflexa var. bracteata, O. disjuncta, O. eriensis, O. eriensis var. niagarensis, O. eriensis var. repandodentata, O. germanica, O. insignis, O. laevigata var. rubripunctata, O. leucophylla, O. litorea, O. magdalena, O. millersii, O. muricata var. parviflora, O. niagarensis, O. nobska, O. oakesiana var. nobska, O. oakesiana var. tidestromii, O. ostreae, O. parviflora var. oakesiana, O. perangusta, O. perangusta var. rubricalyx, O. repandodentata, O. rubescens, O. stenopetala, O. tidestromii, Onagra oakesiana Kneiffia chrysantha, K. depauperata, K. perennis, O. chrysantha, O. perennis var. rectipilis, O. pumila var. chrysantha, O. pumila var. minima, O. pumila var. pusilla, O. pumila var. rectipilis, O. pusilla
Name authority (A. Gray) J. W. Robbins ex S. Watson & J. M. Coulter in A. Gray et al.: Manual ed. 6, 190. (1890) Linnaeus: Syst. Nat. ed. 10, 2: 998. (1759)
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