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

72. Oenothera wolfii (Munz) P. H. Raven, W. Dietrich & Stubbe, Syst. Bot. 4: 244. 1980.
[C E]

Oenothera hookeri Torrey &A. Gray subsp. wolfii Munz, Aliso 2: 16, plate 1, fig. B. 1949; O. hookeri var. wolfii Munz

Herbs biennial or short-lived perennial, densely strigillose, also villous with spreading to subappressed hairs, hairs sometimes pustulate, also glan­dular puberulent distally. Stems erect, green, flushed with red proximally or red throughout, unbranched or branches obliquely arising from rosette and sometimes secondary branches arising from main stem, 50–100 cm. Leaves in a basal rosette and cauline, basal 13–35 ×1.5–4(–5) cm, cauline 5–18 × 1–2.5(–4) cm; blade dull green, flat, oblanceolate to narrowly lanceolate or lanceolate to elliptic, margins bluntly dentate or subentire, teeth widely spaced or sinuate proximally; bracts persistent. Inflorescences erect, unbranched. Flowers opening near sunset; buds erect, 5–8 mm diam., with free tips terminal, erect, 1–3 mm; floral tube 30–46 mm; sepals yellowish green, also usually flushed with red or red-striped, 17–28 mm; petals yellow, fading orange, pale yellow and somewhat opaque, very broadly obcordate, 13–23 mm, conspicuously shorter than sepals; filaments 12–20 mm, anthers 7–12 mm, pollen ca. 50% fertile; style 43–58 mm, stigma usually slightly exserted beyond anthers or surrounded by them at anthesis. Capsules erect or slightly spreading, dark dull green and sometimes red-striped when dry, narrowly lanceoloid, 30–48 × 5–7 mm, free tips of valves 0.5–2.5mm. Seeds 0.9–2 × 0.9–1.3 mm. 2n = 14.

Flowering Jun–Oct. Coarse-textured sandy or rocky sites, coastal dunes and bluffs, loose, sandy sites along roads, moist places; of conservation concern; 0–100(–800) m; Calif., Oreg.

Oenothera wolfii is a PTH species and forms a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous (W. Dietrich et al. 1997). It has plastome I and a AA genome composition. It is known only from the vicinity of Port Orford, Curry County, Oregon (currently apparently only as far north as Otter Rock), south in a scattered distribution through Del Norte County to the mouth of the Mattole River, Humboldt County, California. The distribution, at least in California, is closely associated with small patches of Cenozoic-age marine sediments, isolated from each other by Franciscan sedimentary and metamorphic rocks. Most populations appear to occur near river mouths or to the south of a headland. The largest populations center in the area about 11 km long in the vicinity of Crescent City in Del Norte County, between Point George and Enderts Beach in Redwood National Park. There are collections from two inland California localities, one at the eastern border of Humboldt County, California (Willow Creek, Trinity River Valley), and the other at Carville, Trinity County, that may be O. wolfii. If so, they would presumably represent recent introductions and should be studied further. As summarized by Dietrich et al., O. wolfii is a rare endemic of coastal habitats and known from about 20 different sites. The total number of individuals of O. wolfii apparently fluctuates, with perhaps no more than about 5000 individuals total. It is threatened by any potential development and alteration of its habitat, presently by road maintenance and foot traffic. Another possibly more serious threat comes from the recent spread of O. glazioviana to this area. Oenothera glazioviana could swamp populations through hybridization and, perhaps, by direct competition.

Oenothera wolfii is in the Center for Plant Conservation’s National Collection of Endangered Plants.


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