Oenothera filiformis
Oenothera elata
bee-blossom, longflower beeblossom
evening primrose, Hooker's evening-primrose, western evening primrose
usually well-branched distal to base, (50–)100–400 cm.
erect, green, flushed with red proximally or red throughout, unbranched or branches obliquely arising from rosette and secondary branches arising from main stem, 30–250 cm.
in a basal rosette and cauline, basal 8–15(–40) × 1.5–3.6 cm, blade lyrate, margins irregularly toothed to lobed;
cauline 1.5–13 × 0.5–3 cm, blade narrowly elliptic to elliptic or lanceolate, margins subentire or shallowly undulate-denticulate.
in a basal rosette and cauline, basal 10–43 × 1.2–4(–6) cm, cauline 4–25 × 1–2.5(–4) cm;
blade dull green to grayish green, rarely red, narrowly oblanceolate or oblanceolate to narrowly elliptic or narrowly lanceolate, margins usually flat, rarely undulate, bluntly dentate or subentire, teeth sometimes widely spaced, proximal blades sometimes sinuate-dentate toward base;
bracts persistent.
erect, unbranched.
4-merous, zygomorphic, opening at sunset;
floral tube 4–13(–15) mm;
sepals 7–18 mm;
petals white, fading pink, elliptic to elliptic-obovate, 7–15 mm;
filaments 5–13 mm, anthers 1.5–5 mm, pollen 90–100% fertile;
style 12–34 mm, stigma exserted beyond anthers at anthesis.
opening near sunset;
buds erect, 6–10 mm diam., with free tips terminal, erect, 1–7 mm;
floral tube (20–)30–45(–50) mm;
sepals yellowish green, red-striped or strongly flushed with red, 27–50 mm;
petals yellow to pale yellow, fading orange or pale yellow, very broadly obcordate, (25–)30–47(–55) mm;
filaments 17–25 mm, anthers 8–23 mm, pollen 90–100% fertile;
style 50–90 mm, stigma exserted beyond anthers at anthesis.
ellipsoid or ovoid, sharply 4-angled, 4.5–7 × 1.5–2.5 mm;
sessile.
erect or slightly spreading, dull green or gray-green when dry, narrowly lanceoloid, 20–65 × 4–7 mm, free tips of valves 0.5–2.5 mm.
2–4, yellowish to reddish brown, 1.3–3 × 0.7–1.3 mm.
1–1.9 × 0.6–1.2 mm.
= 14.
Oenothera filiformis
Oenothera elata
P. H. Raven and D. P. Gregory (1972[1973]) found various levels of hybridization and intergradation between Oenothera filiformis and O. lindheimeri to occur where their ranges overlap. In the region of geographical overlap, most populations of O. filiformis are strigillose in the inflorescences and have evening-opening flowers, while O. lindheimeri is villous in the inflorescences, and has large morning-opening flowers. Moreover, O. lindheimeri occurs only on black clay prairie soil, while O. filiformis occurs in light, sandy soil, as it does throughout its range, and in more disturbed areas. Despite these differences, Raven and Gregory found hybridization between these species scattered across an area from eastern Texas across Louisiana to Alabama. At some locations there is apparently no hybridization, while at others hybrids were uncommon to relatively common. Intermediate morning-blooming plants in Alabama appear to represent evidence of past hybridization since O. lindheimeri does not occur there. Many of the individuals they tested had somewhat reduced pollen fertility (40–70% fertile). They suspected that habitat disturbance was primarily responsible in many cases, but they also detected what may have been intergradation resulting from past hybridization outside of the current distribution of O. lindheimeri. Many of these individual cases deserve further investigation to better understand the dynamics of the interactions between these species and if any of the interactions have led to stabilization of novel populations that might be recognized taxonomically.
Very few collections have been made from areas on the periphery of the range of Oenothera filiformis (southern Ontario, Connecticut, Maryland, Massachusetts, Pennsylvania), and populations in these areas probably represent recent human-based introductions. P. H. Raven and D. P. Gregory (1972[1973]) determined O. filiformis to be self-incompatible.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies 3 (2 in the flora).
Subspecies elata differs in anthers 7–12 mm, fewer or no pustulate-based hairs, and generally smaller flowers and habit. It ranges from the highlands of central Mexico, including Guanajuato, Hidalgo, México, Michoacán, Puebla, Querétaro, and Veracruz, south to Guatemala, El Salvador, Costa Rica, and Panama.
Oenothera elata has plastome I and a AA genome composition. Onagra kunthiana Spach is a superfluous name that pertains here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Plants strigillose, usually also villous, with appressed or spreading hairs, sometimes these with red-pustulate bases, distally sometimes also glandular puberulent; buds green to yellowish green, red-striped, or sometimes red throughout; anthers 8–15(–20) mm. | subsp. hirsutissima |
1. Plants strigillose, also villous with appressed or spreading hairs, usually these with conspicuous red-pustulate bases, also glandular puberulent; buds flushed with red; anthers 12–23 mm. | subsp. hookeri |
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