Oenothera grandis
Oenothera filiformis
largeflower eveningprimrose, showy evening-primrose
bee-blossom, longflower beeblossom
erect to ascending, often with ascending lateral branches, 15–60(–100) cm.
usually well-branched distal to base, (50–)100–400 cm.
in a basal rosette and cauline, basal 5–13 × 1–3 cm, cauline 3–10 × 1.5–3.5 cm;
blade green, narrowly oblanceolate to narrowly elliptic, margins lobed or dentate, lobes often dentate;
bracts spreading, flat.
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.
1–few opening per day near sunset;
buds erect, with free tips terminal, erect or hornlike, 1.5–5 mm;
floral tube 25–45 mm;
sepals 15–30 mm;
petals yellow, very broadly obovate or shallowly obcordate, 25–40 mm;
filaments 12–22 mm, anthers 4–11 mm, pollen 85–100% fertile;
style 40–75 mm, stigma exserted beyond anthers at anthesis.
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.
cylindrical, sometimes slightly enlarged toward apex, 25–50 ×2–3 mm.
ellipsoid or ovoid, sharply 4-angled, 4.5–7 × 1.5–2.5 mm;
sessile.
broadly ellipsoid to subglobose, 0.8–1.5 × 0.5–0.9 mm.
2–4, yellowish to reddish brown, 1.3–3 × 0.7–1.3 mm.
= 14.
= 14.
Oenothera grandis
Oenothera filiformis
Oenothera grandis is probably native to eastern New Mexico and Colorado, Arkansas, Kansas, Louisiana, Missouri, Nebraska, Oklahoma, and Texas, and northeastern Tamaulipas, Mexico. Scattered collections made in other states probably represent introductions (W. Dietrich and W. L. Wagner 1988).
Oenothera grandis is self-incompatible (W. Dietrich and W. L. Wagner 1988).
Oenothera laciniata Hill var. occidentalis Small and O. laciniata var. grandis Britton are illegitimate superfluous names based on O. sinuata Linnaeus var. grandiflora S. Watson and pertain here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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