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northern evening-primrose, small-flower 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 perennial, sparsely strigillose, becoming glabrate distally, usually also glandular puberulent distally; from a somewhat fleshy rootstock, forming adventitious roots where submerged.
Stems

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

erect or ascending, usually many-branched throughout, proximal branches often somewhat spongy, 50–120 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, softly succulent, 4–13.5 × 0.8–2.1 cm, petiole 0–1.5 cm, blade lanceolate to elliptic-lanceolate, margins remotely denticulate.

Inflorescences

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

erect, flowers in axils of distalmost few nodes.

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.

opening near sunrise;

buds with free tips 0.5–2(–5) mm, erect to spreading;

floral tube 14–20 mm;

sepals 20–30 mm;

petals bright yellow, fading pale pink or lavender, 16–27 mm;

filaments 10–15 mm, anthers 7–8 mm, pollen 85–100% fertile;

style 15–30 mm, stigma 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.

oblong-clavate to oblong-ellipsoid, 4-angled or 4-winged, and wings 0.1–0.2 mm, 7–15 × 4–6 mm, stipe 2–5 mm;

sessile.

Seeds

1.1–1.8 × 0.5–1 mm.

0.8 × 0.4 mm.

2n

= 14.

= 56.

Oenothera parviflora

Oenothera riparia

Phenology Flowering Jun–Aug. Flowering May–Jul.
Habitat Open or disturbed, sandy or gravelly sites, roadsides, fallow fields, clearings, riverbanks, along water courses, salt marshes, coastal meadows. Isolated colonies in or at edge of water in marshes or slow-running rivers, apparently with at least some tidal influence.
Elevation 0–1700 m. (0–5600 ft.) 0–10 m. (0–0 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
GA; NC; SC; VA
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 riparia has not been accepted as a distinct species for a long time. The conservative approach used by G. B. Straley (1977) is here followed in recognizing a broadly delimited O. fruticosa, except that the very distinctive coastal tidal-freshwater semi-aquatic octoploid populations (Straley 1982) are recognized as O. riparia. Plants of these coastal populations, which occur from southern Virginia to North Carolina, are more robust, more branched, and less pubescent than those of the two subspecies of O. fruticosa, and have slightly succulent leaves and more prominent adventitious roots (Straley 1982; D. Boufford, pers. comm.). Further field studies and cytological analyses are needed to fully understand the geographical and ecological limits of O. riparia and confirm that it is strictly an octoploid species. K. N. Krakos et al. (2014) determined that Oenothera riparia is self-incompatible and is pollinated by bees (Bombus, Lassioglossum, Megachile, Parallelia, Xylocopa, and Zale).

(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. 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. 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. 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 Kneiffia riparia, O. tetragona var. riparia
Name authority Linnaeus: Syst. Nat. ed. 10, 2: 998. (1759) — (as parviflor) Nuttall: Gen. N. Amer. Pl. 1: 247. (1818)
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