CPC National Collection Plant Profile

Lilium occidentale

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CPC National Collection Plant Profile

Lilium occidentale


Family: 
Liliaceae  
Common Name: 
Western lily
Growth Habit: 
Forb/herb
CPC Number: 
2548

Distribution
Protection
Conservation
References


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Lilium occidentaleenlarge
Image Owner: Oregon Department of Agriculture


Lilium occidentale is Fully Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Edward Guerrant, Ph.D. contributed to this Plant Profile.

 
Lilium occidentale


Few wildflowers can rival the beauty and grace of the western lily. If you are fortunate enough to spot one growing in a coastal bog, stop and admire the flowers…but please admire from a distance. With a flower as beautiful as the western lily's, it isn't surprising that horticultural collecting and flower picking are among the greatest threats to this species. Accessible populations have been decimated by members of the public who wild-collect plants. Hikers have been known to pick the sole flowering stalk. When this happens, not only has that person destroyed the plant's opportunity to reproduce that year, but he has also weakened the plant by removing its leaves. Each year, the lily stores energy produced by the leaves in the bulb. This energy is needed to grow and produce a flower the following year. Horticultural collecting has been a problem as well.

Land development, agricultural conversion, and soil compaction have been responsible for the destruction of most populations. Historically, 58 populations were known. Now, only 28 sites are known to contain plants with an additional nine presumed, but not confirmed, to be extant. One tragic instance of habitat destruction illustrates the change in public opinion and government policy over the last 30 years. In the 1960s, a public restroom was built directly over a known population at Shore Acres State Park. The population was completely destroyed. Conservation and habitat protection for native plants are now priorities both for local residents and the government. Lilium occidentale is now listed as Endangered by the Federal government, the states of Oregon and California. Populations on federal and state land are now protected from destructive activities.


Distribution & Occurrence

State Range
  California
Oregon
State Range of  Lilium occidentale
Habitat
  Found growing in bogs composed of poorly drained, slightly acidic, highly organic soils. All populations are found from near sea level to 320 ft (100m) elevation within 6 miles (9 km) of the coast. Associated species include Drosera spp., Rhododendron marcrophyllum, Vaccinium ovatum, Ledum groenlandicum, and Alnus rubra.

Distribution
  Found in California and Oregon

Number Left
  As of 1998: Historically, 55 sites. 18 have been extirpated. 9 of the remaining 37 sites have not been able to be relocated in recent years, so it is not known if plants are still present. Of the 28 sites that have been surveyed, 4 have 1000 or more individuals, 3 have 100-300, 14 have between 10-100, while 7 have fewer than 10 individuals (USFWS 1998).

Protection

Global Rank:  
G1
 
12/16/2005
Guide to Global Ranks
Federal Status:  
LE
 
8/17/1994
Guide to Federal Status
Recovery Plan:  
Yes
 
3/31/1998

State/Area Protection
  State/Area Rank Status Date  
  California S1.2 E 1/1/1982  
  Oregon S1 LE 10/27/1989  

Conservation, Ecology & Research

Ecological Relationships
  Western lily is primarily hummingbird pollinated-- it has non-spreading stamens and yellow or yellow-green tepal centers surrounded by deep red (Schultz 1989). In areas where the hummingbirds migrate before the flowers bloom, insects pollinate Lilium occidentale. The plant reproduces primarily by seed or by bulb scales (Schultz 1989). It does not form large colonies as some other lilies do, as its rhizomatous bulb does not branch (Vollmer 1939).

Young seedlings are extremely vulnerable to desiccation (drying out), and the lily responds to dry years with low emergence (Imper, 1997). Grazing by deer and small mammals increases in dry years, leading to lower reproductive success and adult survival (Imper 1997).
Western lily occupies a fairly specific ecological niche. It grows under the protection of small shrubs, but with nearby direct sunlight (Schultz, 1989). Lilium occidentale may require the small shrubs as mechanical support for their tall flowering stems and heavy flowers. However, it is shaded out by greater than 50% canopy cover or shrubs that are higher than 6ft (2m). Occasional fire or salt spray from the nearby ocean may play a large role in suppressing the growth of forest or dense shrubs (Schultz 1989). The salt spray can damage the L. occidentale leaves and flowers, but it is effective in suppressing the surrounding vegetation. After six successive years of spruce removal at one site, flowering of western lily increased by 2000% within only two years (Imper 1997). Current research and management practices are aimed at finding the most effective and cost efficient method of brush and tree removal.

The Western lily grows in two major types of soils: 1) Deep, organic peat that is saturated for most of the year and 2) mineral-based soils derived from Cenozoic age or older parent material. These tend to be acidic, poorly drained, and have a clay "hard pan" or shallow cemented iron pan within 60 cm of the surface (Imper 1997). Invading trees not only shade out the western lily, but they change the hydrology of the land as well. Their deep roots can penetrate the hard pan causing the land to drain.

Grazing is a threat to Lilium occidentale because it limits reproductive potential. Exclusion of grazing at one site lead to an immediate increase in both flowering and fruit production by more than 300%. However grazing also may help to maintain the open habitat that the lily requires by suppressing vegetation succession. Most surviving populations in Oregon have a long grazing history (Imper 1997). Most damage by cattle occurs by trampling rather than actual consumption. If the Western lily is eaten, it is often a consequence of consuming nearby vegetation, and only the top portion of the shoot is eaten. Deer on the other hand, selectively graze on the lily, often removing the entire shoot (Imper 1997). Impact of cattle is often temporary, since the plant is not completely destroyed by trampling or light grazing. The loss of reproductive success may be offset by the maintenance of habitat that the cattle grazing provides (Imper 1997). Concentrations of seedlings are often found near cattle rest areas or pathways. Lily seeds can pass through cattle intact, and germinate in the feces. They may contribute to the spread of lilies in this way, and also by creating suitable habitat in once unoccupied areas (Imper 1997).

Habitat may have been maintained by periodic burning by Native Americans (USFWS 1998). Natives burned their village areas both for security reasons and to cultivate plants. It is known that Lilium columbianum bulbs were eaten and were actively cultivated by regular burning, digging bulbs, and digging leaves under. Flowering plants were marked with stakes so that the bulbs could be dug in the fall (Gunther 1973). It is hypothesized that L. occidentale was used in a similar manner.

Threats
  • Known populations have been destroyed by: commercial cranberry bog development, ranch development, windfallen trees, the realignment of Highway 101, botanical competition, bulldozing for road construction and powerline right-of-ways, and housing and commercial development. A public restroom was built directly on a known population at Shore Acres State Park in the 1960's (Schultz 1989).
• Degradation of soils by agricultural plowing over the past century and a half "may have been the largest single factor contributing to loss of habitat." Plants are sensitive to increases in soil density. Farming and vehicle use contribute to soil compaction (Imper 1997).
• Habitat destruction due to land development (Meinke 1982), agricultural conversion (Imper et al. 1988), and road construction (Schultz 1989).
• Changes in hydrology due to construction, land filling, laying of sewer lines, and the roots of encroaching trees penetrating the hardpan.
• Horticultural collecting, including flower picking (Meinke 1982).
• Competitive exclusion by shrubs and trees resulting from fire suppression (Shultz 1989).
• Grazing (Schultz 1989) by deer, cattle, and small mammals (esp. voles) (Imper 1997).
• Loss of genetic diversity due to genetic drift and/or inbreeding (USFWS 1998).
• Known populations have been destroyed by: commercial cranberry bog development, ranch development, windfallen trees, the realignment of Highway 101, botanical competition, bulldozing for road construction and powerline right-of-ways, and housing and commercial development. A public restroom was built directly on a known population at Shore Acres State Park in the 1960's (Schultz 1989).
• Degradation of soils by agricultural plowing over the past century and a half "may have been the largest single factor contributing to loss of habitat." Plants are sensitive to increases in soil density. Farming and vehicle use contribute to soil compaction (Imper 1997).
• Habitat destruction due to land development (Meinke 1982), agricultural conversion (Imper et al. 1988), and road construction (Schultz 1989).
• Changes in hydrology due to construction, land filling, laying of sewer lines, and the roots of encroaching trees penetrating the hardpan.
• Horticultural collecting, including flower picking (Meinke 1982).
• Competitive exclusion by shrubs and trees resulting from fire suppression (Shultz 1989).
• Grazing (Schultz 1989) by deer, cattle, and small mammals (esp. voles) (Imper 1997).
• Loss of genetic diversity due to genetic drift and/or inbreeding (USFWS 1998).

Current Research Summary
  • Extensive monitoring at various sites.
• Monitoring at Table Bluff Ecological Preserve for four years prior to the removal of cattle and annually since. The annual average number of flowering plants was less when grazed, but there was a decline in the total number of plants, esp. juveniles, following removal of cattle (Imper et al. 1988, Imper and Sawyer 1999b, and Imper and Sawyer 2000).
• Seed germination studies. A warm treatment of a few weeks induces the first bulblet to be produced. Several weeks of moist cold treatment followed by a few weeks at room temperature cause the cotyledons to emerge (Kierstead 1988).
• Mortality and dormancy studies revealed that floral dormancy occurs in order to conserve resources in response to competitive stress (Schultz 1989).
• Various propagation methods are described in Schultz (1989).
• Experimental Reintroduction of Lilium occidentale: A cooperative project involving the Berry Botanic Gardena and the Coos Bay District of the USDI Bureau of Land Management.
Because the science of reintroducing endangered plants back into the wild from ex situ collections is still in its infancy, we are approaching this project as a controlled scientific experiment. We are asking four classes of questions.
1. Does propagule type used at planting time affect subsequent emergence of plants and/or plant size? We used three classes of propagules at planting time: Yearling bulbs (about the size of half a grain of small rice), New Seeds (planted the year they were collected, 1996), and Old Seeds (seeds that had been collected either one or two years previously, and stored in the seed bank).
2. Another primary question is more practical or management oriented. Does removing the ground cover vegetation at the time of planting have an effect on emergence or plant size?
3. Does source population have an effect on emergence or plant size? We used four of the most local and ecologically similar populations as seed sources.
4. Finally, does maternal plant affect emergence or plant size? A large number of families were used.


Experimental Design
We used a fully randomized split-plot design with 760 propagules (320 new seeds, 320 old seeds, and 120 bulbs) There are 20 replicate plots (38 propagules each). One-half of each plot was randomly selected for ground cover removal.

Summary Results:
Propagule type affected emergence and leaf area. Bulbs emerged at greater rates and produced larger plants than both new or old seeds. Ground cover treatment affected emergence (slightly more plants emerged in areas with ground cover intact), but not leaf area. Source population affect on emergence was strong initially but has diminished over time. The reverse is true for leaf area (source population effect increasing over time)
Effects of maternal parent are complex.
(Guerrant 2001).

Current Management Summary
  • Some sites are protected from development as Ecological reserves and Wildlife areas.
• Informal attempts at population augmentation by spreading seed and replanting bulb-scales (Imper et al. 1988).
• Seeds stored at The Berry Botanic Garden.
• Greenhouse propagation of a seedling bank. Seedlings used for reintroductions. As of 1999, more than 1000 bulbs had been grown for 1-5 years and were available for planting. A total of 150 plants had been established at 4 expansion colonies (CDFG 1999).
• Fencing placed around some populations to decrease grazing by cattle, deer, and small mammals (Schultz 1989 and Imper 1997).
• Seasonal introduction of cattle (Imper 1997)
• Experimental manual vegetation removal (Salzer 1994 in USFWS 1998, and Imper 1997)
• Mowing of grassland (Imper 1997)
• Listed Endangered by USFWS in 1994 (USFWS 1994). Recovery plan approved and implemented in 1998. Lilium occidentale can be downlisted to Threatened when there are at least 20 viable populations (defined as having at least 1,000 flowering plants and a population structure indicating stable or increasing numbers) distributed among the 6 recovery areas (USFWS 1998).

Research Management Needs
  • Controlled burning or girdling to remove competing shrubs and trees (Schultz 1989).
• Continued monitoring at all known sites, especially after habitat alterations (burns, storms, human intervention, etc) (Schultz 1989).
• Further research effect of clearing vegetation around lily plants (USFWS 1998).
• Further research on the effect of deer and cattle grazing (USFWS 1998). Browsing by deer and small mammals may result in a 50% or greater loss of reproductive output. However, complete removal of cattle may actually decrease lily survival by allowing other plants to flourish and compete with the lily. Limited, periodic grazing by cattle to reduce vegetation cover followed by a rest period to allow the lily to develop may be ideal (Imper and Sawyer 2000).
• Study breeding system. Determine whether Lilium occidentale is self-compatible or not (USFWS 1998). There are conflicting reports as to its self-compatibility (Imper et al. 1988).
• Determine the amount and patterns of genetic diversity within and among populations (USFWS 1998).

Ex Situ Needs
  • Collect and store seeds from all extant populations across the species' range (USFWS 1998).
• Determine most effective methods to reintroduce or augment populations.

References

Books (Single Authors)

Abrams, L.; Ferris, R.S. 1944. Illustrated Flora of the Pacific States: Washington, Oregon, and California. Stanford, CA: Stanford University Press.

Eastman, D.C. 1990. Rare and Endangered Plants of Oregon. Beautiful America Publishing Company. 194p.

Gunther, E. 1977. Ethnobotany of Western Washington: the knowledge and uses of indigenous plants of Native Americans. Seattle, WA: University of Washington Press.

Meinke, R.J. 1982. Threatened and Endangered Vascular Plants of Oregon: An Illustrated Guide. Portland, Oregon: U.S. Fish & Wildlife Service, Region 1. 326p.

Munz, P.A.; Keck, D.D. 1959. A California flora. Berkeley, CA: Univ. California Press. 1681p.

Nakamura, Gary; Kierstead Nelson, J. 2001. Illustrated Field Guide to Selected Rare Plants of Northern California. University of California, Agriculture and Natural Resources. Publication 3395. 370p.

ONHP. 2001. Rare, Threatened and Endangered Plants and Animals of Oregon.

Synge, P.M. 1980. Lilies: A Revision of Elwes' Monograph of the Genus Lilium and its Supplements. London: B.T. Batsford, Ltd.

Webb, L. 1988. A Guide: to sensitive plants of the Siskiyou National Forest. Forest Service, USDA. Pacific Northwest Region, Siskiyou National Forest. 255p.

Books (Sections)

Imper, D.K. 1997. Ecology and Management of the Endangered Western Lily (Lilium occidentale) in Northwestern California. Conservation and Management of Native Plants and Fungi. Native Plant Society of Oregon. Corvalis, OR. p 22-33.

Books (Edited Volumes)

James C. Hickman, Editor. 1993 The Jepson manual: Higher plants of California. Berkeley: University of California Press. 1400p.

Electronic Sources

(2000). CalFlora: on California plants for education, research and conservation. [web application]. Berkeley, California: The CalFlora Database [a non-profit organization]. http://www.calflora.org/.. Accessed: 2002.

CDFG. (2001). Special Vascular Plants, Bryophytes, and Lichens List. Biannual Publication, Mimeo. 141 pp. California Department of Fish and Game, Natural Diversity Database. Accessed: 2001.

CNDDB. (2000). Calfornia Natural Diversity Data Base (CNDDB). Version 2.1.2. California Natural Diversity Database. Accessed: California Department of Fish and Game, Sacramento.

ONHDB. (2000). Oregon Natural Heritage Program Database. Portland, Oregon.

Journal Articles

Guerrant, E.O. 1996. Western Lily, Lilium occidentale (Liliaceae). Kalmiopsis. 6: 17-18.

Kline, E.L. 1984. Cultivating West Coast lilies. Journal of the North American Lily Society. 38, 8: 11-13.

Lindh, B. 1996. Conservation Corner: Seeds and Rare Plants. Newsletter, The Berry Botanic Garden. 9, 4: 4.

Purdy, C. 1897. New West American lilies (Original Publication). Erythea. 15: 103-104.

Purdy, C. 1935. Western American lilies. Royal Horticultural Society Lily Yearbook. 1935: 43-54.

Purdy, C. 1937. Western American lilies. Royal Horticultural Society Lily Yearbook. 1937: 20-25.

Raven, A. 1996. Conservation Corner: Rare Plant Field Season. The Berry Botanic Garden Newsletter. 9, 2: 4.

Stafford, R.D. 1989. Diverse Organizations Act to Halt Rare Lily's Decline. Plant Conservation: A Publication of the Center for Plant Conservation. 4, 4

The California Endangered Species Campaign. 1991. Western lily: rescued from extinction. Wild Life Lines. 1, 2: 2-3.

USFWS. 1976. Proposed Endangered Status for 1700 U.S. Plants. Federal Register. 41: 24523-24572.

USFWS. 1992. Listing Proposals. Endangered Species Technical Bulletin. 17, 9-11: 8.

USFWS. 1994. Determination of Endangered Status for Lilium occidentale (Western Lily). Federal Register. 59, 158: 42171-42176.

Vollmer, Dr. 1939. Lilium pardalinum and its allies. Journal of the Royal Horticultural Society. 64, 9: 414-424.

Newspaper Articles

Anderson, D. 1996 Thursday, Oct. 3, 1996. Rare North Coast flower increases in numbers. Times-Standard; Eureka, California.

Reports

Ballantyne, O. 1980. A Preliminary study of Lilums bolanderi, occidentale, vollmeri and wigginsii. Unpublished report. p.162+.

CDFG. 1999. Department of Fish and Game (DFG) Experience with the Western Lily. California Department of Fish and Game. Unpublished report. p.4.

Guerrant, E.O. 2001. Experimental reintroduction of western lily (Lilium occidentale) at the New River ACEC: Results of the first four years of growth. Unpublished report to the Coos Bay District of the USDI Bureau of Land Management. p.44.

Imper, D.K.; Hovey, G.E.; Sawyer, J.O.; Carlson, S.A. 1988. Table Bluff Ecological Reserve Management Plan. Interagency Agreement C-1582.2. California State University. California Department of fish and Game. p.89.

Imper, D.K.; Sawyer, J.O. 1999. 1999 Monitoring Report, Western Lily. Table Bluff Ecological Reserve, California. Unpublished report prepared under Interagency Agreement, California State University/Department of Fish and Game. p.11 +.

Imper, D.K.; Sawyer, J.O. 1999. 1999 Western Lily Monitoring Report, Highway 101 West, Humboldt Road, and Humboldt Road West Sites. Crescent City Marsh Wildlife Area, California. Unpublished report prepared under Interagency Agreement, California State University/Department of Fish and Game. p.9 +.

Imper, D.K.; Sawyer, J.O. 2000. 1998-1999 Status Report, Western lily Vegetation Strategy. Crecent City Marsh Wildlife Area and Table Bluff Ecological Reserve, California. Unpublished report prepared under Interagency Agreement, California State University/Department of Fish and Game. p.21 +.

Larkin, G.; Salzer, D. 1992. A plant demography study of Delphinium leucocephalum, Thelypodium howellii ssp. spectabilis, Astragalus applegatei, and Lilium occidentale: preliminary report 1990ϋ1991. Portland, Oregon: The Nature Conservancy, Oregon Field Office.

Nelson, L.S. 1999. Survey of Threatened and Endangered Wetland and Aquatic Plants at Four Corps of Engineers Districts. US Army Corps of Engineers Waterways Experiment Station. p.15 + appendices. Technical Report A-99-1.

Schultz, S.T. 1987. Pollination and Phenology of Lilium occidentale Purdy: Summer, 1987. Unpublished report. p.5.

Schultz, S.T. 1989. Status Report on Lilium occidentale. Salem, OR: Endangered Species Program, Plant Division, Oregon State Department of Agriculture. p.70.

USFWS. 1998. Recovery Plan for the Endangered Western lily (Lilium occidentale). Portland, Oregon: U.S. Fish and Wildlife Service. p.82.

Theses

Skinner, M.W. 1988. Comparative pollination ecology and flood evolution in Pacific Coast Lilium. [Ph.D. Thesis]: Harvard University. Cambridge, MA.


  This profile was updated on 7/8/2010
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