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FNA | Family List | FNA Vol. 10 | Onagraceae | Oenothera

24. Oenothera howardii (A. Nelson) M. E. Jones ex Prain in B. D. Jackson et al., Index Kew. suppl. 3: 121. 1908. (as howardi).

Lavauxia howardii A. Nelson, Bot. Gaz. 34: 368. 1902 (as howardi)

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.

Flowering May–Jul. 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; (1000–)1500–2300(–3000) m; Colo., Kans., Nev., Utah, Wyo.

Oenothera howardii 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.


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