CPC Plant Profile: Cascade Head Catchfly
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Plant Profile

Cascade Head Catchfly (Silene douglasii var. oraria)

A large Silene douglasii var. oraria plant in a grass and herb dominated habitat. Photo Credit: S. Vrilakas
Description
  • Global Rank: T1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Caryophyllaceae
  • State: OR
  • Nature Serve ID: 155902
  • Date Inducted in National Collection: 02/25/1988

Three varieties of Silene douglasii are currently recognized (Kephart et al. 1999). Silene douglasii var. douglasii is the most widespread and is found in southern British Columbia, Washington, Idaho, Montana, Utah, Nevada, northern California and eastern and southern Oregon. Silene douglaii var. oraria and var. rupinae are very limited in their distribution. Silene douglasii var. rupinae is limited to a few locations on open, rocky outcrops along the Columbia River Gorge in Oregon and Washington. Silene douglasii var. oraria, which is listed as Threatened in Oregon, is found only in three coastal prairie sites in Oregon which are separated by approximately 30 to 75 miles (50-120 km). It is not known whether these plants once had a more extensive distribution. As late as the 1880s, coastal prairie was found extensively along the Oregon coast for a distance of nearly 250 miles (400km) (Kephart and Paladino 1997). Human caused disturbances and habitat succession have effectively destroyed most of this important habitat type.

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Updates
Center for Plant Conservation
  • 12/02/2021
  • Reintroduction

Genetic factors influence the population variability of rare species, yet the fitness consequences of inbred and outbred progeny are seldom tested emperically in reintroduction strategies designed for species recovery or habitat restoration. Rare and endangered plants of Silene occur on four continents, including North America. In Oregon, inbred and outbred progeny were monitored by the Willamette University for three years after experimental reintroduction of a narrow endemic, S. douglasii var. oraria, into formerly grazed habitat within its presumed historical range. Survival and reproduction were compared for progeny that were derived from the seeds of seld- versus crossed-pollinated flowers produced in situ at Cascade Head, a UNESCO Biosphere Reserve where the largest of three extant populations occurs. Progeny of cross-pollinated flowers had significantly greater field survival in all years than did offspring of selfed or open-pollinated flowers. Outbred progeny also significantly exceeded other treatment cohorts in canopy area, and produced more reproductive stems and flowers than other progeny types of the same maternity. For plots varying in plant density, mortality was greatest in the high-density competitive regime but the survivors reached significantly larger sizes and reproductive capacities than in low density plots. In all, successful conservation plans involving reintroduction may require genetically diverse progeny to offset inbreeding depression as well as suitable planting densities and source populations.

Center for Plant Conservation
  • 12/02/2021
  • Reproductive Research

Genetic factors influence the population variability of rare species, yet the fitness consequences of inbred and outbred progeny are seldom tested emperically in reintroduction strategies designed for species recovery or habitat restoration. Rare and endangered plants of Silene occur on four continents, including North America. In Oregon, inbred and outbred progeny were monitored by the Willamette University for three years after experimental reintroduction of a narrow endemic, S. douglasii var. oraria, into formerly grazed habitat within its presumed historical range. Survival and reproduction were compared for progeny that were derived from the seeds of seld- versus crossed-pollinated flowers produced in situ at Cascade Head, a UNESCO Biosphere Reserve where the largest of three extant populations occurs. Progeny of cross-pollinated flowers had significantly greater field survival in all years than did offspring of selfed or open-pollinated flowers. Outbred progeny also significantly exceeded other treatment cohorts in canopy area, and produced more reproductive stems and flowers than other progeny types of the same maternity. For plots varying in plant density, mortality was greatest in the high-density competitive regime but the survivors reached significantly larger sizes and reproductive capacities than in low density plots. In all, successful conservation plans involving reintroduction may require genetically diverse progeny to offset inbreeding depression as well as suitable planting densities and source populations.


Center for Plant Conservation
  • 12/02/2021
  • Genetic Research

Genetic factors influence the population variability of rare species, yet the fitness consequences of inbred and outbred progeny are seldom tested emperically in reintroduction strategies designed for species recovery or habitat restoration. Rare and endangered plants of Silene occur on four continents, including North America. In Oregon, inbred and outbred progeny were monitored for three years after experimental reintroduction of a narrow endemic, S. douglasii var. oraria, into formerly grazed habitat within its presumed historical range. Survival and reproduction were compared for progeny that were derived from the seeds of seld- versus crossed-pollinated flowers produced in situ at Cascade Head, a UNESCO Biosphere Reserve where the largest of three extant populations occurs. Progeny of cross-pollinated flowers had significantly greater field survival in all years than did offspring of selfed or open-pollinated flowers. Outbred progeny also significantly exceeded other treatment cohorts in canopy area, and produced more reproductive stems and flowers than other progeny types of the same maternity. For plots varying in plant density, mortality was greatest in the high-density competitive regime but the survivors reached significantly larger sizes and reproductive capacities than in low density plots. In all, successful conservation plans involving reintroduction may require genetically diverse progeny to offset inbreeding depression as well as suitable planting densities and source populations.


Center for Plant Conservation
  • 11/26/2021
  • Propagation Research

After introducing a total of >1800 seeds, the Willamette University compared experimentally manipulated and natural populations of widespread Silene douglasii var. douglasii relative to rare S. douglasii var. oraria, known in only three coastal headlands of Oregon. Despite equivalent ex situ germination, oraria field plots produced significantly fewer juveniles than douglasii plots indicating that seedling survival limits plant establishment. We also evaluated transplant vs. seed reintroductions as restoration tools, the effect of inbreeding on fitness, and the potential importance of buried seed pools. Germination declined rapidly for seeds over 1-2 years old, and only 2.2% of newly collected seeds of oraria survived as seedlings. Transplant survival over 3 years was greatest for outbred proginy, furthermore 75% of the new seedlings emerged near outbred progeny from original reintroduction. Despite similar ovule numbers and pollinator visitation, transplants exhibited 49-179% maladaptation in the formerly grazed site, with significantly lower fruit and seed set than adults in more diverse natural populations. This study experimentally identified several key factors affecting reintroduction, facilitating effective development of large-scale reintroduction strategies for native plants.

Center for Plant Conservation
  • 11/26/2021
  • Reintroduction

After introducing a total of >1800 seeds, the Willamette University compared experimentally manipulated and natural populations of widespread Silene douglasii var. douglasii relative to rare S. douglasii var. oraria, known in only three coastal headlands of Oregon. Despite equivalent ex situ germination, oraria field plots produced significantly fewer juveniles than douglasii plots indicating that seedling survival limits plant establishment. We also evaluated transplant vs. seed reintroductions as restoration tools, the effect of inbreeding on fitness, and the potential importance of buried seed pools. Germination declined rapidly for seeds over 1-2 years old, and only 2.2% of newly collected seeds of oraria survived as seedlings. Transplant survival over 3 years was greatest for outbred proginy, furthermore 75% of the new seedlings emerged near outbred progeny from original reintroduction. Despite similar ovule numbers and pollinator visitation, transplants exhibited 49-179% maladaptation in the formerly grazed site, with significantly lower fruit and seed set than adults in more diverse natural populations. This study experimentally identified several key factors affecting reintroduction, facilitating effective development of large-scale reintroduction strategies for native plants.

  • 09/29/2020
  • Genetic Research

Genetic studies using microsatellite DNA are currently underway (Kephart and Yee, unpublished in: Kephart et al. 1999).

  • 09/29/2020
  • Propagation Research

Germination trials at The Berry Botanic Garden indicate that this species germinates readily under a variety of conditions but that it does slightly better when subjected to cold stratification and constant temperatures. 100% of seeds germinated when subjected to 8 weeks of cold stratification followed by constant 68F (20C) and 80% germinated when cold stratification was followed by alternating 50F/68F (10/20C) temperatures. Without cold stratification, 80% of seeds germinated in the constant temperature treatment and 60% germinated under the alternating temperature treatment (BBG File).

  • 09/29/2020
  • Reproductive Research

Studies to determine the mating system and to quantify the magnitude of inbreeding depression were conducted. Flower treatments included emasculation (removal of pollen) followed by treatment with the plant's own pollen (self) or another plant's pollen (outcross), bagging (exclusion of pollinators), and open pollination. Silene douglasii var. oraria has a mixed mating system. It is capable of setting seed with its own pollen or pollen from another plant. Inbreeding depression was high compared to many outcrossing species (Kephart et al. 1999). Studies of the pollination biology of Silene douglasii var. oraria. Natural pollen deposition was monitored. Fruit production, seed number and weight, and progeny vigor were studied for different pollination treatments (selfed, open pollinated, and different amounts of supplemental pollen). Overall, it appears that most natural pollen transfer involves self-pollination and low reproductive success reflects low pollen quantity and quality (Brown and Kephart 1999).

  • 09/29/2020
  • Demographic Research

Long term (10 year) demographic monitoring of Silene douglasii var. oraria in two habitat types (grassy and rocky) at one site to aid in determining long-term population trends and habitat preferences. At the conclusion of the study, population growth appeared stable in the rocky sites and slightly declining in the grassy. Plants growing in the grassy habitat were more sparse but larger than plants growing in the rocky habitat. There was more seedling recruitment and adult survivorship in the open, rocky sites (Kephart and Paladino 1997). The three varieties of Silene douglasii (var. oraria, var. douglasii, and var. rupinae) were compared using a wide variety of morphological characteristics. Significant differences among varieties were found, reinforcing the categorization of the three varieties. Significant differences were also found within each of the three varieties, indicating geographic differences and population substructuring (Kephart et al. 1999).

  • 09/29/2020
  • Reintroduction

Re-introduction of more than 200 individuals grown in the greenhouse into formerly grazed habitat (in Brown and Kephart 1999).

  • 09/29/2020
  • Orthodox Seed Banking

Seeds from two occurrences are currently stored at The Berry Botanic Garden.

  • 09/29/2020
  • Seed Collection

Seeds from two occurrences are currently stored at The Berry Botanic Garden.

Nature Serve Biotics
  • 05/02/2017

Extremely low numbers of individuals and populations. Habitat and range extremely restricted. Threatened by hikers and potentially climate change.

Edward Guerrant, Ph.D.
  • 01/01/2010

Heavy recreational use (Meinke 1982). Competition from aggressive, weedy species (Meinke 1982). Coastal development and deforestation leading to habitat degradation and fragmentation (Brown and Kephart 1999). Habitat fragmentation leading to reduce

Edward Guerrant, Ph.D.
  • 01/01/2010

3 known populations. The largest contains over 1000 individuals. The other two sites contain fewer than 100 individuals (Brown and Kephart 1999).

Edward Guerrant, Ph.D.
  • 01/01/2010

Long term (10 year) demographic monitoring of Silene douglasii var. oraria in two habitat types (grassy and rocky) at one site to aid in determining long-term population trends and habitat preferences. At the conclusion of the study, population growth appeared stable in the rocky sites and slightly declining in the grassy. Plants growing in the grassy habitat were more sparse but larger than plants growing in the rocky habitat. There was more seedling recruitment and adult survivorship in the open, rocky sites (Kephart and Paladino 1997). The three varieties of Silene douglasii (var. oraria, var. douglasii, and var. rupinae) were compared using a wide variety of morphological characteristics. Significant differences among varieties were found, reinforcing the categorization of the three varieties. Significant differences were also found within each of the three varieties, indicating geographic differences and population substructuring (Kephart et al. 1999). Studies to determine the mating system and to quantify the magnitude of inbreeding depression were conducted. Flower treatments included emasculation (removal of pollen) followed by treatment with the plant's own pollen (self) or another plant's pollen (outcross), bagging (exclusion of pollinators), and open pollination. Silene douglasii var. oraria has a mixed mating system. It is capable of setting seed with its own pollen or pollen from another plant. Inbreeding depression was high compared to many outcrossing species (Kephart et al. 1999). Studies of the pollination biology of Silene douglasii var. oraria. Natural pollen deposition was monitored. Fruit production, seed number and weight, and progeny vigor were studied for different pollination treatments (selfed, open pollinated, and different amounts of supplemental pollen). Overall, it appears that most natural pollen transfer involves self-pollination and low reproductive success reflects low pollen quantity and quality (Brown and Kephart 1999). Germination trials at The Berry Botanic Garden indicate that this species germinates readily under a variety of conditions but that it does slightly better when subjected to cold stratification and constant temperatures. 100% of seeds germinated when subjected to 8 weeks of cold stratification followed by constant 68F (20C) and 80% germinated when cold stratification was followed by alternating 50F/68F (10/20C) temperatures. Without cold stratification, 80% of seeds germinated in the constant temperature treatment and 60% germinated under the alternating temperature treatment (BBG File). Genetic studies using microsatellite DNA are currently underway (Kephart and Yee, unpublished in: Kephart et al. 1999).

Edward Guerrant, Ph.D.
  • 01/01/2010

Seeds from two occurrences are currently stored at The Berry Botanic Garden. The largest known population is on private land that is managed by The Nature Conservancy. The two other known populations are on State Park land. This species is listed as threatened by the state of Oregon, so plants on state land are protected from destruction and development. Re-introduction of more than 200 individuals grown in the greenhouse into formerly grazed habitat (in Brown and Kephart 1999).

Edward Guerrant, Ph.D.
  • 01/01/2010

Fence plants to limit herbivory and trampling. This will help maintain adequate numbers of flowering plants to help reduce inbreeding depression (Brown and Kephart 1999). Minimize the encroachment of shrubs (Kephart and Paladino 1997). Develop an effective method of reducing litter accumulation and other cover in grassy habitats (Kephart and Paladino 1997).

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seeds from all known populations. Determine propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Silene douglasii var. oraria
Authority (M. Peck) C.L. Hitchc. & Maguire
Family Caryophyllaceae
CPC Number 3994
ITIS 530362
USDA SIDOO
Common Names Cascade head catchfly | seabluff catchfly
Associated Scientific Names Silene douglasii var. oraria | Silene oraria
Distribution OR: Coast Range
State Rank
State State Rank
Oregon S1
Habitat

Grassy meadows and rocky outcrops that are part of the coastal prairie habitat type located on steep bluffs, ledges, and slopes facing the Pacific Ocean. Associated species include Koeleria nitida, Festuca rubra, Delphinium menziesii, Castilleja litoralis, Clarkia amoena, Eriophyllum lanaturm, Senecio bolanderi, and Rhus diversiloba.

Ecological Relationships

Silene douglasii var. oraria often produces many branches from just below the surface. This creates a compact cluster of leafy stems. Each stem can root, but they generally remain attached to the parent plant. Occasionally, a portion of the plant will die above ground, creating what looks like several individual plants growing in close proximity. This can make it difficult to correctly census the population, but careful mapping can make estimation possible (Kephart and Paladino 1997).Plants begin to put on new growth in late March. Flowering begins in late April and early May. New seedlings can be observed by May (Kephart and Paladino 1997). Seedling recruitment for this species is very low. In one study, only 5%-8% of the seedlings survived one year. Plants exhibit high levels of inbreeding depression, which may be linked to low vigor and ultimately plant death (Brown and Kephart 1999). Flowers of Silene douglasii var. oraria are protandrous, meaning that the anthers mature and shed pollen before the stigmas mature. However, flowers vary considerably in the timing of pollen shed, and self-pollination appears to occur. Outcrossing is facilitated by pollen gathering halictid bees (Lasioglossum sp.) and syrphid flies, but according to recent studies, pollen transfer appears to be limiting the reproductive potential of this rare plant (Brown and Kephart 1999).Silene douglasii var. oraria has fairly specific habitat requirements. Plants cannot tolerate much competition for light from other plants or a heavy litter layer. In an extensive demographic study, it was found that seedling and adult survivorship were greatest in an open, rocky habitat. However, the soil conditions in the rocky habitat are not ideal, and plants in the deeper soils of the grassy habitat were observed to be larger than those growing on rocky soil. Management activities should take these preferences into consideration. The encroachment of shrubs and trees should be minimized, and an effective method of reducing litter layer accumulations in grassy habitats should be developed (Kephart and Paladino 1997).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Sweat bees Halictidae Floral Visitor Link
Flies
Syrphid flies Syrphid flies Floral Visitor Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting
Willamette University Oregon Reintroduction 1998

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