Herbs acaulescent or some­times caulescent, moderately to densely strigillose and glandular puberulent, sometimes also sparsely to moderately hirsute; from a taproot, sometimes lateral roots producing adventitious shoots. Stems (when present) ascending, longer ones becoming decumbent, leafy, sometimes densely so, 0–10 (–30) cm. Leaves in a basal rosette, sometimes also cauline, (6–) 8.5–17 (–23) × (0.5–) 1–2 (–3) cm; petiole 2–7.5 cm; blade usually oblanceolate, elliptic to nar­rowly oblong, rarely lanceolate, margins often undulate, entire or remotely and irregularly pinnately lobed mostly in proximal 1/2, rarely more regularly pinnately lobed and lobing extending to distal 1/2, sinuses usually extending less than 1/2 to midrib, lobes triangular to oblong or linear, (1–) 4–9 (–13) mm, apex acute to obtuse. Flowers usually 1 or 2, rarely more, opening per day near sunset, strongly and sweetly scented; buds with unequal free tips 1–3 (–4) mm; floral-tube (43–) 60–110 (–125) mm; sepals (30–) 35–60 (–80) mm; petals brilliant yellow, fading deep red, drying deep reddish purple to reddish-brown, usually broadly obovate, rarely subrhombic, (30–) 40–60 (–73) mm, sometimes with a terminal tooth; filaments (19–) 25–38 mm, anthers 10–17 mm; style (90–) 110–145 (–165) mm, stigma exserted beyond anthers at anthesis. Capsules leathery, ovoid, narrowly ovoid, or narrowly lanceoloid to broadly ellipsoid, winged, wings (2–) 4–7 (–11) mm wide, body (20–) 25–50 (–80) × 4–6 mm, dehiscent 1/4–1/3 their length; pedicel 2–6 mm. Seeds numerous, usually in 1 row per locule, rarely in 2 rows toward base, obovoid to subcuboid, 3–8 × 2.5–3.5 mm. 2n = 28, 42, 56.

Phenology: Flowering May–Jul.
Habitat: Open or rocky areas, in shale, fine-textured sandstones, clays, gypsum, or limestone from High Plains grasslands, open sites in pinyon-juniper woodlands, ponderosa pine-Douglas fir forests.
Elevation: (1000–)1500–2300(–3000) m.

Distribution

• Generated Map
• Legacy Map

Colo., Kans., Nev., Utah, Wyo.

Discussion

Oenotherahowardii is known from three disjunct areas: three collections on the High Plains (Baca and Otero counties, Colorado, and Hamilton County, Kansas); open yucca-juniper grassland, rocky slopes or disturbed areas on shale substrates along the Colorado counties of Boulder, Denver, Jefferson, and Larimer, and just over the state line in Wyoming; and, common to scattered, mostly on rocky slopes but also in shaded canyon sites on fine-textured red sandstones, clays, gypsum, chalky white degraded limestone or limestone in pinyon-juniper woodland to ponderosa pine-Douglas fir forest in southern Utah and eastern Nevada.

A. Nelson intended to publish Lavauxia howardii as a new combination and base it on Oenothera howardii M. E. Jones (1893), which was not validly published at the time, but inadvertently published L. howardii as a new species. Oenothera howardii (A. Nelson) W. L. Wagner is an isonym.

Selected References

None.

Lower Taxa

None.

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