Western Lily

Lilium occidentale

Description

The western lily, Lilium occidentale, a perennial in the lily family (Liliaceae), grows from a short un-branched, rhizomatous bulb, reaching a height of up to 5 ft (1.5 m). Leaves grow along the unbranched stem singly or in whorls and are long and pointed, roughly 0.4 in (1 cm) wide and 0.5 in (1.3 cm) by 4 in (10 cm) long. The nodding flowers are red, sometimes deep orange, with yellow to green centers in the shape of a star and spotted with purple. The six petals (tepals) are 1-1.5 in (2.5-4 cm) long and curve strongly backwards. This species can be distinguished from similar native lilies by the combination of pendent red flowers with yellow to green centers in the shape of a star, highly reflexed petals, non-spreading stamens closely surrounding the pistil, and an unbranched rhizomatous bulb. Lilium columbianum is yellow to orange and grows from a typical ovoid bulb; L. vollmeri, L. pardilinum, and L. maritimum can have red tepals, but none have the distinctive characters of stamens that stay close to the pistil and a green central star, which may change to yellow with age.

The life history of the western lily has been studied much more extensively than most other endangered species. Like other lilies, western lily has her-maphroditic flowers, producing both pollen and seeds. It reproduces primarily by seed, but asexual reproduction is possible from detached bulb scales growing into new plants.

Cultivated plants take four to five years to flower for the first time, and live for 25 years or more. Young flowering plants generally produce a single flower in each of the first few years they begin to flower. If they experience favorable environmental conditions, progressively more flowers will be produced. Populations of non-flowering individuals may persist for many years under closed forest canopies. It is not clear whether these represent the remnants of populations that flowered in the past when conditions were different, or are the product of dispersal into conditions that allow juveniles to persist but not reproduce. In nature, shoots emerge in March-April and continue to elongate until the flowers open. From May to July, green buds turn red for three to five days, open over a period of one to two days, and the nodding flowers last for seven to ten days. After the floral parts have fallen off, flower stalks become erect within a week and capsules enlarge to maturity over a period of 40-50 days. Seeds are primarily dispersed by wind and gravity, mostly within a 13 ft (4 m) radius. Each year, the above ground portion of the plants die back and individuals overwinter underground as rhizomes/bulbs. Dead, above-ground shoots may persist for one or more years in protected sites before they collapse and decompose.

Hummingbirds are the primary pollinator of western lily, but some bees and other insects may also occasionally transfer pollen. Low fruit set in isolated plants or those concealed in dense vegetation, relative to those plants in groups with flowers free of surrounding vegetation, underscores the importance of having their flowers be available to hummingbirds. In a comparative study of the pollination ecology of seven west coast lily species, the western lily produced more nectar in a day than any other lily species—almost twice the amount of the runner-up, Lilium maritimum, and over 15 times as much as the least productive, L. humboldtii. Most lilies cannot successfully pollinate themselves, and the western lily may be unique in being able to produce considerable quantities of self-pollinated seed.

Habitat

The western lily grows at the edges of sphagnum bogs and in forest or thicket openings along the margins of ephemeral ponds and small channels. It also grows in coastal prairies and scrub near the ocean where fog is common. Herb and grass associates include Pacific reedgrass, sedge, sphagnum moss, Gentiana sceptrum, and California pitcher-plant. Common shrub associates are wax-myrtle, Labrador tea, Douglas' spiraea, salal, western rhododendron, evergreen huckleberry, and blackberry. Tree associates include coast pine, sitka spruce, Port Orford cedar, and willow.

The western lily occurs in bogs or coastal scrub on poorly drained soils, usually those underlain by an iron pan, or poorly permeable clay layer. Populations are found at low elevations, from almost sea level to about 300 ft (100m) in elevation, and from ocean-facing bluff's to about 4 mi (6.5 km) inland.

The climate is characterized by cool, wet winters and warm, dry summers. About three-quarters of the rain falls from October to May. Summers are dominated by the North Pacific high pressure zone, which generates moderate but consistent northwest winds. Fog is common in the summer and moisture condensing on trees may increase annual rainfall by as much as a quarter.

The western lily appears to require a habitat that maintains a delicate balance of having some surrounding shrubbery but not too much. Low vegetation, less than 3 ft (1 m) tall, is in most cases beneficial to the lily because it shelters juvenile plants from large mammal browsing, and provides heat cover in July and August. This protection is perhaps most critical in spring and early summer for seedlings. However, dense, tall shrub growth reduces reproduction and survivorship, and closure of forest canopy eventually eliminates the population entirely. The flowers often emerge above surrounding shrubs, gaining exposure to direct sunlight where they are available to pollinators, primarily hummingbirds. The smaller size classes, and even adult plants until they are within a week of flowering, are generally protected by shrubs from wind and direct sunlight. Plants growing in prairie habitats with little structural support tend to be smaller when they flower than those with support. Plants growing in cultivation tend to not be able to hold themselves erect without artificial support, suggesting that the surrounding vegetation may be an important component of their habitat. Even so, the western lily tends to be shaded out when the vegetation is especially dense or taller than about 6.5 ft (2 m).

Western lily populations appear to have been maintained in the past by occasional fires, at least at some sites in Oregon, and by grazing. Among the most serious current threats is loss of habitat due to ecological succession facilitated by aggressive fire suppression. What effects these vegetational changes have had on hydrological aspects of western lily habitat, and vice versa, is not well understood.

In Oregon, the occurrence of the western lily appears correlated with strongly acid, poorly drained, sandy hardpan soils, where it occupies low-nutrient coastal bogs, and possibly regularly disturbed medium to high nutrient bogs. If the soils have not been badly damaged, such sites can sometimes return to scrub/prairie vegetation relatively quickly when grazing is removed.

Distribution

The western lily has not been widespread in recent times. Historical records indicate that it was once more common than it is today. After the Ice Age, rising sea levels flooded marine benches where bogs and coastal scrub would have been more extensive than today. That may account for the patchiness of its current habitat distribution. It is known or assumed to be extirpated in at least nine historical sites, due to forest succession, cranberry farm development, livestock grazing, highway construction, and other development. Its status is uncertain in at least seven other historical sites. These factors continue to threaten the lily, with development taking a primary role.

Of the 25 populations known in 1987 and 1988, nine contained only two to six plants, five contained 10-50 plants, six contained 51-200 plants, four contained 201-600 plants, and one contained almost 1,000 plants. At some sites, particularly the sites with more than 200 plants, the majority of plants were non-flowering, which is probably an indication of stress. Schultz calculated a known population of 661 flowering and at least 2,750 non-flowering plants in 1988. Since then, an estimated total of 1,000-2,000 flowering plants have been discovered at four sites near Crescent City, California, where none were previously known. In addition, a population of about 125 flowering plants was discovered near Brookings, Oregon, in 1991, and a population of 13 flowering plants was discovered near Bandon, Oregon, in 1992. The known populations occur on State of California (2), State of Oregon (15), county (1), and private (15) lands, including 1 site on land owned by The Nature Conservancy. Two sites span dual ownership.

In Oregon in 1989, biologists identified a 20 mi (32 km) stretch of coast from Bandon to Cape Blanco as an area likely to contain undiscovered populations of the western lily. A 1980 search of this area did not find new populations, but the search was conducted after flowering when the plants would have been inconspicuous. It is possible this area may support the lily. In California, little suitable habitat remains that has not already been surveyed. The extremely dense vegetation in the coastal scrub habitat and around bogs makes surveying for the lily difficult.

Threats

The western lily is a showy, rare lily and the species has been collected by lily growers and for commercial trade since before the 1930s. After the location of a California population of L. occidentale was published in lily society yearbooks in 1934, 1955, and 1972, bulb collecting by lily growers and breeders decimated the population. Overcollection continues sporadically at sites in Oregon and California. For example, in June 1987, seven bulbs were dug from an Oregon site. Lily breeders collect L. occidentale seed regularly from several sites. Plants near trails and roads are occasionally picked: at least seven plants were picked in 1985, four to six in 1986, five in 1987, and two in 1988 at a site in Oregon. The western lily was reportedly advertised for sale in the western United States and in British seed and bulb catalogs. Overcollection currently threatens this plant and would likely increase, if specific locations of this plant were publicized.

The primary long-term natural threat to the western lily is competitive exclusion by shrubs and trees as a result of succession in bogs and coastal prairie/scrub. Human activities such as draining of wetlands, clearing of land, elimination of beaver, and stabilization of moving sand areas have interrupted the natural processes of bog and wetland creation. As late-stage bogs and coastal scrub go through succession to forest, lily habitat is eliminated with little new habitat being created. There is some indication that lily populations have been maintained in the past by periodic fires, perhaps set by Native Americans. Charcoal is abundant in the soil at several of the major populations, indicating past fires. Fires are now rare events in these areas.

Young plants of this species are almost always recruited under shrub cover, but the lily is shaded out if the canopy cover is greater than 50% or shrubs are over 6 ft (2 m) high. Several populations and portions of populations have already been extirpated by forest succession. Eleven populations (ranging from two to about 1,000 plants) are seriously stressed from competition, as indicated by low reproductive rates. Individual plants do not flower every year, apparently as an energy-saving mechanism when stressed. Health of a population can be evaluated by the number of flowering versus non-flowering plants, and the number of blooms per plant. It has been suggested that the 11 stressed populations would probably survive less than a decade without habitat manipulation. Invasion by the exotic shrub gorse (Ulex europaeus ) into the bog habitat of the western lily has eliminated suitable habitat in Oregon near Blacklock Point. At four California ranch populations, livestock enclosure fences have solved the immediate problem of overgrazing. A limited amount of grazing may actually benefit the species by preventing succession. Over time, without habitat management, forest succession within the enclosures would limit the lilies to the well-lighted edges of the enclosures and reproduction would deteriorate.

Some populations are so small (two to 100 flowering plants) that loss of genetic variability is a threat. Plants with genetic abnormalities such as 4-merous flowers, tepals replacing stamens, stamens replacing tepals, and double flowers have been observed over two or more seasons at sites in both California and Oregon. The effects of inbreeding may already be adversely affecting the viability of these small populations and remains a future threat to the western lily.

Until recently, livestock overgrazing on the lily and surrounding vegetation was severe at three California ranch sites. The lily population at one ranch was reduced from over 100 flowering individuals in 1984 to fewer than ten between 1985 and 1988. At another ranch, half of the fruits were grazed by deer and cattle in 1985. By July 1987, cattle had crushed 32% and grazed another 25% of 49 flowering shoots. Only 17 intact fruits remained in August of 1987. Deer and elk herbivory is severe at three Oregon sites; 50-60% of fruit in one population of about 60 flowering plants were browsed in 1987 and 1988. Unknown vandals destroyed all flowering shoots at one site in 1980.

Deer browsing continues to be a threat at the Oregon sites, as ranch fences are not deer-proof. Though occurring sporadically, browsing by deer can cause major damage.

Grazing of leaves, buds, and flowers by Coleopteran and Lepidopteran larvae is an ongoing threat at one California site. The highly clumped distribution and small number of populations of the western lily make any fungal, viral, or bacterial disease a potential threat. Fungal pathogens are common in cultivated lilies; growers often avoid planting in ground known to be contaminated.

Conservation and Recovery

The endangerment of the western lily has been recognized for a long time. Much has been and is being done to recover the species already by public agencies, private organizations, and individuals.

In California, private individuals, in conjunction with Humboldt State University and the California Department of Fish and Game, have had a formal management plan in place since 1987 for the Table Bluffsite. Since that time, considerable work has been done to recover the western lily at the Table Bluff Ecological Reserve site and an extensive yearly monitoring record has been generated at this site and the three nearby sites on private land. In addition to relatively passive measures various forms of experimental habitat manipulation have been attempted, and an experimental reintroduction program has been established for the Table Bluff Ecological Reserve. Additional experimental habitat manipulation and monitoring studies, facilitated by The Nature Conservancy, have been conducted on three private holdings in the vicinity of Humboldt Bay-the Barry, Christensen, and Johnson sites.

In Oregon, The Nature Conservancy has been monitoring a small population at Bastendorff Bog since 1985, and in 1994 initiated experimental manual vegetation removal in an attempt to reverse a well documented decline in population size. The Berry Botanic Garden has a few collections of western lily seed in the Seed Bank for Rare and Endangered Plants of the Pacific Northwest. The collections are biased toward populations near the northern and southern limits of the range. There is also a seedling bank project at Humboldt Bay.

Contact

U.S. Fish and Wildlife Service
Office of the Regional Director
Eastside Federal Complex
911 N.E. 11th Avenue
Portland, Oregon 97232-4181
Telephone (503) 231-6118
Fax: (503) 231-2122

References

U.S. Fish and Wildlife Service. 17 August 1994. "De-termination of Lilium occidentale to Be a Threatened Species." Federal Register 59 (158): 42171-42175.

U. S. Fish and Wildlife Service. 31 March 1998. "Final Recovery Plan for the Endangered Western Lily." U.S. Fish and Wildlife Service, Portland.