80. Oenothera oakesiana (A. Gray) J. W. Robbins ex S. Watson & J. M. Coulter in A. Gray et al., Manual ed. 6. 190. 1890.
Oenothera biennis Linnaeus var. oakesiana A. Gray, Manual ed. 5, 178. 1867; O. ammophila Focke; O. ammophiloides R. R. Gates & Catcheside; O. ammophiloides var. angustifolia R. R. Gates; O. ammophiloides var. laurensis R. R. Gates; O. atrovirens Shull & Bartlett var. ostreae (A. H. Sturtevant) R. R. Gates; O. canovirens E. S. Steele var. cymatilis (Bartlett) R. R. Gates; O. cruciata Nuttall var. stenopetala (E. P. Bicknell) Fernald; O. cymatilis Bartlett; O. deflexa R. R. Gates var. bracteata R. R. Gates; O. disjuncta Boedijn; O. eriensis R. R. Gates; O. eriensis var. niagarensis (R. R. Gates) R. R. Gates; O. eriensis var. repandodentata (R. R. Gates) R. R. Gates; O. germanica Boedijn; O. insignis Bartlett; O. laevigata Bartlett var. rubripunctata R. R. Gates; O. leucophylla R. R. Gates; O. litorea Bartlett; O. magdalena R. R. Gates; O. millersii de Vries; O. muricata Linnaeus var. parviflora R. R. Gates; O. niagarensis R. R. Gates; O. nobska A. H. Sturtevant; O. oakesiana var. nobska (A. H. Sturtevant) R. R. Gates; O. oakesiana var. tidestromii (Bartlett) R. R. Gates; O. ostreae A. H. Sturtevant; O. parviflora var. oakesiana (A. Gray) Fernald; O. perangusta R. R. Gates; O. perangusta var. rubricalyx R. R. Gates; O. repandodentata R. R. Gates; O. rubescens Bartlett; O. stenopetala E. P. Bicknell; O. tidestromii Bartlett; Onagra oakesiana (A. Gray) Britton
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. 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. 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. Inflorescences usually recurved with ascending tip distally, rarely suberect, unbranched. 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. 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. Seeds 1.1–1.2 ×0.8–1 mm. 2n = 14.
Flowering Jun–Aug. Sandy coastal meadows and dunes, gravelly or rocky sites along rivers, disturbed sites, roadsides; 0–50(–500) m; Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Conn., Del., D.C., Ill., Ind., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., Ohio, Pa., R.I., Vt., Va., Wis.; introduced in Europe, Asia.
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.