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Plant Profile

Wolf's Evening-primrose (Oenothera wolfii)

The bright yellow flowers of Wolf's evening primrose. Photo Credit: Tom Kaye

Global Rank: G2 - Imperiled
Legal Status: N/A
Family: Onagraceae
State: CA, OR
Nature Serve ID: 136043
Lifeform: Forb/herb
Date Inducted in National Collection: 03/08/1989

Description:

Of all the many ways to be driven to extinction, Wolf's evening primrose is under assault from one of the most insidious and bizarre; its own offspring! We believe that children are a blessing. We believe that genetic diversity and the mixing of genomes is a good thing. In the botanical world, these assumptions aren't always true. Oenothera wolfii grows along the coast of Oregon and northern California. It has been found growing in cracks in a parking lot, along the upper strand of the beach, on bluffs above the ocean, and along roadsides; all areas subject to a moderate amount of disturbance especially from sea spray and blowing sand. It exhibits many characteristics typical of an "opportunist" species such as high germination rates and low seedling survival. According to a local botanist, Oenothera wolfii "is as easy to grow as any I've seen, which makes one wonder why it is so rare" (Stansell 1989). So, what makes this plant rare Its peculiar habitat limits it to specific sites along the coast. It is found mostly on discontinuous patches of Cenozoic-era marine deposits, which are isolated from each other by other sedimentary and metamorphic rock. This may explain the disjunct distribution of the species. Within these sites, it requires well-drained soils with adequate moisture, minimal competition and protection from northwesterly exposure. The infrequency of sites that match these conditions may contribute to its rarity. Rarity, in and of itself, is not necessarily of great conservation concern. What is of concern, however, are the multitude of threats to this species. This rare plant is, like so many other species, threatened by loss of habitat due to urban expansion and road paving, and from direct damage to plants by construction and herbicide spraying. Competition from non-native plants is also a problem. The threat from its own offspring is the most damaging and worrisome. Perhaps the most serious and most worrisome threat is from its own offspring. The ornamental species Oenothera glazioviana originated in Europe, apparently as a stabilized hybrid between two North American species brought to Europe for ornamental purposes. It has been spreading around the globe, not only as a garden plant, but also as a weed. Oenothera glazioviana has become naturalized on every continent except Antarctica. Oenothera glazioviana is an out-breeder and is able to accept pollen from O. wolfii, thus producing viable hybrid offspring. Oenothera wolfii is an inbreeding species and apparently cannot accept pollen from other species. However, O. wolfii has been found to be receptive to pollen from the hybrids, and introgression, or the infiltration of one species' genes into another, is occurring. The genetic integrity of Wolf's evening primrose throughout much of the range in California is questionable (Imper 1997). Scientists are concerned that all O. wolfii genotypes will be diluted by the influence of O. glazioviana and this unique species will vanish from existence. Why bother maintaining the genetic integrity of this species As a part of a natural ecosystem, Oenothera wolfii plays an important ecological role. We may not fully understand the full impact of its value and its relationship to other species until it is gone. This species may also prove to be useful to humans, and if we allow it to become extinct, we may never know the benefits (see the ecology section for more).

Where is Wolf's Evening-primrose (Oenothera wolfii) located in the wild?

Habitat:

Oenothera wolfii can be found on sandy soil in grasslands, coastal strand, roadsides, and coastal bluffs, which are well drained but with adequate moisture. Sites are often in areas protected from northwesterly exposure, usually situated south of a headland or promontory or near the mouth of a river.

Distribution:

Found in Del Norte and Humboldt counties in California and on the southern coast range in Oregon.

States & Provinces:

Wolf's Evening-primrose can be found in California, Oregon

Which CPC Partners conserve Wolf's Evening-primrose (Oenothera wolfii)?

Rae Selling Berry Seed Bank & Plant Conservation Program

Not Sponsored

Conservation Actions

Assigned 06/09/17

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

09/23/2020

Mitigation project near Trinidad, Humboldt County, CA. Plants were transplanted from the area to be paved over and seeds collected that year were sown in suitable habitat. There was initial success, as the number of flowering individuals increased through 1993. The population declined from 1994-1995 and now seems to be sustained at a very low level (Imper 1997). Approximately 300,000 seeds were spread in a variety of habitats along a County right-of-way in Northern California in order to establish a widespread population (Imper 1997).

09/23/2020

Researchers with the Oregon Department of Agriculture have developed effective cultivation protocols for O. wolfii in the greenhouse (Gisler, pers. comm.). Ongoing research into determining the hybrid status of its extant populations (hybrids with introduced Oenothera glazioviana) (Gisler, pers. comm.) Researchers at the Oregon Department of Agriculture are planning future work to cultivate and outplant this species to start new populations that are secure from the threat of hybridization (Gisler, pers. comm.).

09/23/2020

Germination trials at the Berry Botanic Garden. Two different lots of seed from different parents were subjected either to 8 weeks of cold stratification or no cold stratification. That was followed by either constant 68F (20C) or alternating 50/68F (10/20C) temperatures. For the first batch (old seeds), All treatments had 60% germination except the no cold stratification treatment which had 100% germination. For the second batch (new seed), the cold stratified-50/68F treatment had 80% germination. Both the cold stratified 68F treatment and the straight 68F treatment had 60% germination. The straight 50/68F treatment had 40% germination (BBG File).

09/23/2020

09/01/2020

Based on an September 2020 extract of the California Plant Rescue Database, Rae Selling Berry Seed Bank & Plant Conservation Program holds 2 accessions of Oenothera wolfii in orthodox seed collection. There are as many as 7050 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

08/05/2020

Based on an August 2020 extract of the California Plant Rescue Database, Rae Selling Berry Seed Bank & Plant Conservation Program has collected 2 seed accessions of Oenothera wolfii from 1 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 2 maternal plants

Nature Serve Biotics

05/02/2017

Known from southwestern Oregon and adjacent northwestern California. As of 2015, approximately 33 sites are known along the coastline. Several sites have Threatened by hybridization with non-native Oenothera species, coastal development, road construction and maintenance, herbicide applications, foot traffic, and non-native plants.

Edward Guerrant, Ph.D.

01/01/2010

The greatest threat to this species is the displacement of natural populations by fertile plants resulting from hybridization with Oenothera glazioviana leading to the eventual genetic swamping of the O. wolfii genotype (Imper 1997). Coastal developmen

Edward Guerrant, Ph.D.

01/01/2010

As of 1997: Approximately 16 sites (7 sites in Oregon, 9 California), scattered over 160 miles (260 km) of coastline between Cape Mendocino, CA and Port Orford, OR. 6 sites contained fewer than 50 individuals, 5 contained 100-1000, 4 contained 2000-3000, and one had more than 5,000 (Imper 1997).

Edward Guerrant, Ph.D.

01/01/2010

Germination studies comparing different temperature regimes. Alternating 59F/77F (15C/25C) resulted in the greatest germination percentages for 3 of the 10 seed lots tested (each lot from different parent plants) (Kaye 1999). For 7 of the 10 seed lots, the 15C/25C treatment was statistically indistinguishable from the 68F/86F (20C/30C) treatment. Constant 59F (15C) and constant 68F (20C) treatment showed much lower germination percentages (Kaye 1999). Germination trials at the Berry Botanic Garden. Two different lots of seed from different parents were subjected either to 8 weeks of cold stratification or no cold stratification. That was followed by either constant 68F (20C) or alternating 50/68F (10/20C) temperatures. For the first batch (old seeds), All treatments had 60% germination except the no cold stratification treatment which had 100% germination. For the second batch (new seed), the cold stratified-50/68F treatment had 80% germination. Both the cold stratified 68F treatment and the straight 68F treatment had 60% germination. The straight 50/68F treatment had 40% germination (BBG File). Informal germination studies/observations. High germination percentages with no treatment and no cold stratification. Highest germination rates in sandy potting mixture (~50%). Seeds germinated rapidly after sowing (Stansell 1989). Researchers with the Oregon Department of Agriculture have developed effective cultivation protocols for O. wolfii in the greenhouse (Gisler, pers. comm.). Ongoing research into determining the hybrid status of its extant populations (hybrids with introduced Oenothera glazioviana) (Gisler, pers. comm.) Researchers at the Oregon Department of Agriculture are planning future work to cultivate and outplant this species to start new populations that are secure from the threat of hybridization (Gisler, pers. comm.).

Edward Guerrant, Ph.D.

01/01/2010

Edward Guerrant, Ph.D.

01/01/2010

Suggested legal protection in California (Imper 1997). Ban use of herbicide in habitat occupied by Oenothera wolfii (Imper 1997). Limit roadside maintenance to periods after seed has matured in the summer and before re-growth in the spring (Imper 1997). Public outreach project to limit the use of Oenothera glazioviana in the garden and encourage the use of native species (Imper 1997). Establish new populations in areas isolated from the threat of Oenothera glazioviana (Imper 1997).

Edward Guerrant, Ph.D.

01/01/2010

Collect and store seed from across the species range. Attempt to get seed from ""pure"" stands of Oenothera wolfii.