Oenothera mckelveyae
Oenothera flava
Mckelvey's beeblossom
long-tubed evening primrose, yellow evening primrose
ascending, branched below or just above ground, branched also proximal to inflorescences, 30–70(–120) cm.
(when present) ascending, 1–several, usually densely leafy, 0–2 cm.
in a basal rosette and cauline, basal 3–17 × 0.8–2 cm, blade oblanceolate, cauline 1–6.5 × 0.1–1.5 cm, sessile, blade narrowly oblanceolate to elliptic, margins conspicuously sinuate-dentate, often undulate.
primarily in a basal rosette, (3.4–)6–30(–36) × (0.5–)1.5–5(–7) cm, flexible, sometimes ± fleshy;
petiole (0.2–)2–7(–10) cm;
blade oblanceolate to linear, margins usually irregularly and coarsely pinnately lobed, rarely subentire, apex acute.
slender.
4-merous, zygomorphic, opening near sunset;
floral tube 2–3.5 mm;
sepals 6–12 mm;
petals white, fading dark pink to red, slightly unequal, elliptic-obovate, 7–11 mm, long-clawed;
stamens presented in lower 1/2 of flower, filaments 5–9 mm, lanate at very base, anthers 2–4 mm, pollen 90–100% fertile;
style 9–16 mm, stigma exserted beyond anthers at anthesis.
1–4 opening per day near sunset;
buds with free tips (1–)2–10(–12) mm;
floral tube (24–)40–200(–265) mm;
sepals (8–)11–40(–42) mm;
petals bright yellow, sometimes paler (in smaller-flowered plants), fading pale orange, drying purple, (7–)10–45(–50) mm;
filaments (5–)8–23(–26) mm, anthers (2–)3–13(–16) mm;
style (40–)50–250(–290) mm, stigma exserted beyond or surrounded by ring of anthers.
reflexed, lanceoloid to narrowly ovoid, narrowly 4-winged, 8–19 × 1.5–2 mm, tapering to a sterile stipe 3–9 mm.
leathery in age, surface usually conspicuously reticulate, usually narrowly ovoid or ellipsoid, sometimes ovoid or lanceoloid, winged, wings narrowly oblong, (2–)3–5(–6) mm wide, confined to distal 2/3 of capsule, (10–)20–35(–43) × 4–8 mm (excluding wings), gradually constricted to a short beak, dehiscent 1/4–1/2 their length, valve surface usually conspicuously reticulate;
sessile.
(1 or)2–4, 2–3 × 1 mm, yellowish to reddish brown.
asymmetrically cuneiform, 1.8–2.2(–2.6) mm.2n = 14.
= 14.
Oenothera mckelveyae
Oenothera flava
Oenothera mckelveyae, on the Rio Grande Plain, is found in an area bounded by from Dimmit and LaSalle counties east to Karnes and Refugio counties in the north, southward through south Texas, extending to northeastern Tamaulipas and adjacent Nuevo León. P. H. Raven and D. P. Gregory (1972[1973]) found Oenothera mckelveyae to be self-incompatible.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Petals in Oenothera flava typically range from 7–32 mm with floral tubes 24–100 mm; however, plants from three disjunct areas: the Mogollon Plateau in Arizona to Catron County, New Mexico; Sacramento Mountains and Sierra Blanca, Lincoln and Otero counties, New Mexico; and the Sierra Madre Occidental from northern Chihuahua south to Durango, have much larger petals (30–55 mm) and longer floral tubes (80–265 mm). They were originally recognized as a distinct species or most recently as a subspecies (O. flava subsp. taraxacoides), but detailed study of the variation pattern suggests that the larger flowers occur in areas of high hawkmoth species diversity and higher rates of outcrossing, similar to the pattern discussed in detail by D. P. Gregory (1963, 1964). R. A. Raguso et al. (2007) and H. E. Summers et al. (2015) came to the same conclusion in an independent study of floral biology of sect. Lavauxia. Because populations from the three disjunct areas appear to have diverged independently from lower-elevation source populations, it seems best to treat the complex as one variable species without any formal subdivision.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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