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northern evening-primrose, small-flower evening-primrose

heartleaf evening primrose

Habit Herbs biennial, sparsely strigillose, glandular puberulent, and villous with pustulate or non-pustulate hairs, sometimes predominately strigillose proximally or predominately villous with pustulate or non-pustulate hairs distally, glabrous, or some mixture of strigillose, glandular puberulent, or sparsely villous distally, sometimes appearing glabrous to the naked eye. Herbs annual or biennial, densely to sparsely strigillose, glandular puberulent or sometimes also sparsely villous distally.
Stems

erect, green or red on proximal parts or throughout, mostly branched from base or only in distal 1/2, 30–150 cm.

unbranched or branched primarily distally, 25–70 cm.

Leaves

in a basal rosette and cauline, basal 10–30 × 1–4 cm, cauline 4–18 × 1–3 cm;

blade usually bright green, sometimes pale green distally, white- or red-veined, narrowly oblanceolate, narrowly elliptic to lanceolate, or oblong, margins usually flat, rarely undulate, regularly dentate to remotely denticulate, sometimes teeth widely spaced;

bracts persistent.

in a basal rosette and cauline, basal 6–12 × 0.7–2 cm, cauline 2–10 ×0.5–3 cm;

subsessile;

blade narrowly elliptic to oblanceolate, gradually narrowly lanceolate to lanceolate, elliptic, or ovate distally, margins lobed to remotely dentate or subentire;

bracts shorter than capsule they subtend, 0.5–1.7 cm.

Inflorescences

erect or ± curved, unbranched or with secondary branches just proximal to main one.

open, lax, usually unbranched, mature buds usually overtopping spike apex.

Flowers

opening near sunset;

buds erect, 3–5 mm diam., with free tips subterminal, spreading to erect, 0.5–5 mm;

floral tube 22–40 mm;

sepals green to yellowish green or flushed with red or dark red, sometimes only red-flecked, 7–17 mm;

petals yellow to pale yellow, fading pale yellow to pale yellowish orange, very broadly obcordate, 8–15(–20) mm;

filaments 7–13 mm, anthers 3.5–6 mm, pollen ca. 50% fertile;

style 25–50 mm, stigma surrounded by anthers at anthesis.

1–few per spike opening per day near sunset;

buds erect, with free tips erect, 1–3 mm;

floral tube nearly straight, 20–40 mm;

sepals 15–25 mm;

petals yellow, broadly elliptic to rhombic-ovate, 20–30 mm;

filaments 17–22 mm, anthers 4–7 mm, pollen 85–100% fertile;

style 50–65 mm, stigma usually exserted beyond anthers at anthesis.

Capsules

erect or slightly spreading, usually greenish black when dry, narrowly lanceoloid to lanceoloid, 20–40 ×3.5–5 mm, free tips of valves 1–1.5 mm.

narrowly lanceoloid, 15–33 × 2–3 mm.

Seeds

1.1–1.8 × 0.5–1 mm.

dark brown, ellipsoid, 1–1.4 ×0.4–0.6 mm.

2n

= 14.

= 14.

Oenothera parviflora

Oenothera cordata

Phenology Flowering Jun–Aug. Flowering Apr–Jul.
Habitat Open or disturbed, sandy or gravelly sites, roadsides, fallow fields, clearings, riverbanks, along water courses, salt marshes, coastal meadows. Sandy, open places in oak woodlands.
Elevation 0–1700 m. (0–5600 ft.) 30–200 m. (100–700 ft.)
Distribution
from FNA
CT; DC; DE; IA; IL; IN; KY; MA; MD; ME; MI; MN; MO; NC; ND; NH; NJ; NY; OH; PA; RI; TN; VA; VT; WI; WV; BC; NB; NF; NS; ON; PE; QC [Introduced in Europe, Asia (ne China, Japan), s Africa, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
TX
[BONAP county map]
Discussion

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

Onagra chrysantha Spach 1835, not Michaux 1803, is a superfluous name, as is Onagra chrysantha var. parviflora (Linnaeus) Spach, and both pertain here. O. biformiflora var. cruciata R. R. Gates is an invalid name that pertains here.

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

Oenothera cordata is self-incompatible. It occurs in a narrow range in eastern Texas (Austin, Bastrop, Colorado, Fayette, Guadalupe, Goliad, Matagorda, San Patricio, Victoria, Waller, and Wilson). It apparently occasionally hybridizes with O. heterophylla subsp. heterophylla where their ranges come together.

Oenothera bifrons D. Don 1838 (not Lindley 1831) 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. Oenothera > subsect. Oenothera Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Candela
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. oakesiana, O. organensis, O. pallida, 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. 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
Synonyms O. ammophiloidesr. var. flecticaulis, O. ammophiloides var. parva, O. angustifolia, O. angustissima, O. angustissima var. quebecensis, O. apicaborta, O. atrovirens, O. biennis var. cruciata, O. biennis var. parviflora, O. biformiflora, O. cleistantha, O. comosa, O. cruciata, O. cruciata var. sabulonensis, O. deflexa, O. flecticaulis, O. hazeliae, O. hazeliae var. parviflora, O. hazeliae var. subterminalis, O. intermedia, O. laevigata, O. laevigata var. scitula, O. laevigata var. similis, O. novae-scotiae, O. novae-scotiae var. distantifolia, O. novae-scotiae var. intermedia, O. parva, O. parviflora subsp. angustissima, O. parviflora var. angustissima, O. robinsonii, O. rubricapitata, O. scitula, O. subterminalis, O. venosa, Onagra biennis var. cruciata, O. chrysantha var. cruciata, O. cruciata, O. parviflora
Name authority Linnaeus: Syst. Nat. ed. 10, 2: 998. (1759) — (as parviflor) J. W. Loudon: Ladies’ Flower-gard. Ornam. Perenn. 1: 167. (1843)
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