Lilium occidentale

Purdy 1897

Western lily

Lilium occidentale (Hansen)


  • Section: Pseudolirium (North America)
  • Origin: United States, Pacific Northwest coast (Southern Oregon & Northern California)
  • Habitat: freshwater fens, sphagnum bogs, costal prairie, transition zones between the two. from sea-level (0m) to 400ft (100m) in elevation; Pacific ocean- 4-miles (6km) inland.
  • Type: Wetland
  • Status: Critically Endangered

Introduction: Perhaps one of the rarest of the lily species, L. occidentale is listed as a critically endangered lily, and is only found growing along a very narrow 200-miles (320km) strip along the West Coast of the United States in the Pacific Northwest from central Oregon to Northern California.

Its rarity has everything to do with habitat destruction and fragmentation. The primary threat to this lily, like many endangered species, is human activity. Rather than being a fragile flower, L. occidentale is a robust strong-growing plant in its natural habitat and in the garden. No more difficult than L. pardalinum to grow, it presents no real difficulty or special care. And once established, specimens can last 20-30 years and longer.

Description: L. occidentale is typical of most American West Coast wetland lilies. The bulb is rhizomatous with many small joined scales. These scales readily propagate if broken off and planted and may represent another method by which the lily reproduces asexually if disturbed by flood, or dug by animals. The rhizome does divide but not as vigorously as L. pardalinum, so it does not form large clumps of clones. It also forms small bulbils at the base of the stem. The stem rises anywhere from 2 feet to 7-8 feet (0.6-2m) depending on location and population genetics. In many locations it is literally growing on cliffs overlooking the Pacific. It is obviously very tolerant of salt and harsh conditions.

The flowers are very distinctive and unique being a classic down-facing Turk's cap of glowing vibrant red to dark red, with a distinct yellow star at the center with black spotting, and lime green nectar furrows which also form a distinct green star pattern. There can be as few as one to as many as 30 -flowers on a stem. The anthers are purple non-spreading and held tight to the pistil, with red-orange pollen. Bloom time depends on weather, but it usually begins in around the first of July, though I have seen specimens in bud as late as September.

Seed is small and light brown, hypogeal in late fall with cool temperatures.

Habitat: Lilium occidentale occurs in freshwater fens, coastal prairie and scrub, and the transition zones between these vegetation types. Sites are often near the ocean (within a 100 meters) where fog is common. Evidence suggests fog condensing on vegetation and dripping may provide an important late season moisture source (Imper and Sawyer 1996). Populations occur from just above sea level, to a maximum 300 feet (100m) in elevation, and from ocean-facing bluffs nearly 4 miles inland.

There is little doubt L. occidentale prefers disturbed locations and early successional habitats, such as along trails, grazing pastures, open wetlands that flood seasonally, and areas burned by fire. Areas that are frequently disturbed to remove competition are its preferred habitat. That being said, another crucial factor is a habitat that maintains a delicate balance between maintaining adequate moisture to avoid desiccation during the growing season, and avoiding prolonged inundation when it needs to grow; thus, the close association with soils that have a “perched” water table with a hardpan soil to inhibit adequate drainage near the surface that allows the soil to stay relatively moist, or where the water table drops seasonally to expose the bulbs to air circulation (FAE - Fresh Air Exchange) during the growing season is essential. These two balancing acts, with respect to moisture and disturbance, substantially limit the kinds of habitats the species can effectively thrive in, and probably explains much of its rarity.

There is strong evidence to suggest that prior to European settlement in the 1850’s, Lilium occidentale habitat was burned repeatedly by Native Americans as a way to maintain grazing pastures for their natural game (early evidence of game management), and for berries and other plants species they ate that preferred open wetland areas, such as camas lily (Camassia spp.), along its natural range along the coast (Anderson 2006, Bicknell and Austin 1991, Schultz 1989), which may explain the frequent occurrence of the species on coastal headlands. This frequent burning maintained the open wetland, marshes, and pastures preferred by the lily.

The species occurs on two types of soils, decomposed peat or muck substrate, or soils that are poorly drained due to a shallow iron pan or clay layer. In all known occurrences, the soils are high-quality native soils, exhibiting good structure, very low bulk density (on the order of 55-60 pounds (24-27kg) per cubic foot (0.2 cubic meters) or less, and high organic content (Imper et al. 1987, Imper and Sawyer 1994, Imper, unpubl. data 2008). Although Lilium occidentale habitat appears to vary dramatically across its range (e.g., freshwater marsh, coastal prairie, spruce forest), all sites share many common features. The most important being a high ‘perched’ water table, adequate moisture year around, and a water table that is high and seasonally inundates the immediate area thus removing competition and maintaining an open habitat, but then either drops seasonally to allow the bulb to be exposed to air during the growing season, or is seasonally high but has elevated areas that allows the bulb to ‘perch’ itself high enough above the water table (6-inches/15cm or more) to avoid inundation. Evidence suggests that the most important reason or the requirement of a high water table is first, to ensure the removal of competition from successional species such as Sitka Spruce (Picea sitchensis) and other large tree species that otherwise would choke the lily out. And secondly, to help maintain adequate moisture year around. This very uniform, lower elevation of the plant bulbs suggests the high water table, and its duration, is a keystone factor in controlling not only the distribution of a population, but also controls where it can effectively flourish within a wetland.

Although the species often occurs in fens that are flooded for periods in the winter and spring, the species does not tolerate year-round inundation like L. paradlinum or its variants such as L. pardalinum ssp. vollmeri will, or tolerate saturated soils during the growing season. L. occidenatle is especially sensitive to inundation during the growing season. Even though it is generally described as a wetland lily, it should be noted that many wetland plants do not necessarily like wet or saturated conditions, but rather tolerate those conditions better than other plants. High water tables where water remains above the bulb during the growing season have caused as high as 50% percent mortality in populations. Research of populations where water levels remain high during the growing season has provided more evidence of this sensitivity to prolonged inundation.

Plants growing within bogs, fens and other wetlands consistently occur within an elevation band of only 6 inches (15cm) above the high water mark, situated on mounds or along the edge approximately 9 inches (23cm) above the floor of the fen (Imper, unpub. data 2008). At the same time, there is abundant evidence indicating the species requires available soil moisture late into the growing season. In general, field monitoring and greenhouse propagation efforts over many years have confirmed a sensitivity of this species to desiccation, particularly in the seedling stage (Imper 2001; Imper and Sawyer 1991, 1992a, 1993, 1994). This and other evidence suggests that even a minor alteration of the population site hydrology that results in either extending the period bulbs are under water, or causes the soils to dry out earlier in the season, could have a significant impact on the mortality of L. occidentale. Ironically these conditions generally do not exist in a garden setting. As moisture levels tend to be more uniform and are easily manipulated. (need to add source info)

Climate: The climate is characterized by cool, wet winters and warm, dry summers. About three-quarters (52-inches/132cm) of the rain falls from October to May. Summers are dominated by the North Pacific high pressure zone (A semi-permanent, subtropical area of high pressure in the North Pacific Ocean. It is strongest in the Northern Hemispheric summer and is displaced towards the equator during the winter when the Aleutian Low becomes more dominate. Comparable systems are the Azores High and the Bermuda High.) (NOAA) which generates moderate but consistent northwest winds and fog. The average rainfall along the Southern Oregon Northern California coast is 71.24 inches (1,810 millimeters). The wettest months are from October to March; the wettest month is December with an average of 13.70 inches (348.0 millimeters), and the driest month is July with 0.35 inches (9mm). This is mean decrease of 93% from winter precipitation. Mean summer (July-September) precipitation is 0.7-inches (17mm). Mean Fall (October-December) precipitation is 9.4-inches. Mean winter (January-March) precipitation is 9.6-inches (243mm). Mean annual daily temp is 52F° (11C), mean high temp is 60F° (15.5C), mean low temp is 44.3F (6C). Mean winter temp (January-March) is 40F (4C). Mean summer temp (July-September) 58F (13C). With the exception of precipitation, it is a very stable and consistent environment with regards to temperature and to a lesser extent rainfall during the wet months. (U.S. Fish & Wildlife report, Climate data NOAA)

General Information: L. occidentale is a critically endangered species. The issue is that the lily grows on land that is prime real-estate for cranberry farmers, resorts and golf courses, housing developments, etc. For example, at one location at a state park, a population was accidentally destroyed to build a public bathroom. At other locations residential housing and roadways are literally just feet away. Road construction, drainage ditches, wells for irrigation, all affect hydrology which has a negative impact on the lily. At places where it grows on private land, other issues complicate the lily's survival. Endangered plants do not appreciate the same protection in the United States as endangered animals. Endangered plants on private land are at the mercy of the landowner. Many landowners are happy to cooperate with local, state, and federal agencies to help mitigate and protect populations. Other landowners aren't so caring and do not allow monitoring or mitigation of populations on their land.

Another factor that is crucial to the lilies survival is genetic diversity, or the lack thereof. Many populations are isolated due to habitat fragmentation from human activity, and the flow of genetic material from one population to another is either restricted or cut off altogether. Many of these populations have so few breeding individuals that genetic drift (the random loss of alleles due to random chance) is a serious threat, as well as inbreeding, or just too few breeding individuals to produce enough seed to overcome natural factors like seed predation and grazing by deer, etc. To complicate this, there is considerable debate among various personalities on how to best deal with this issue. Some consider each population a unique population with distinct genetics and reject introducing new genetic material into populations for fear of destroying the uniqueness of the population. Others advocate introducing genetic material from other nearby populations to revitalize the genetic bank of populations cutoff and isolated.

Another key issue is suppression of natural fires. Like many Western American lilies L. occidentale is a fire chaser, and relies heavily on fire to maintain its habitat and remove competition. Being a wetland plant, it can tolerate saturated areas better than some other species and this offers some protection as many competitive species are flooded or drowned out. But other species, like Sitka spruce, can tolerate the wet conditions and thrive, thus out-competing the lily. Without fire to remove these competitive species they soon choke out the lily, and the primary pollinator, hummingbirds, can't find the flowers in the heavy vegetation to pollinate the flowers. Also, as stated earlier, due to the proximity of many populations to residential housing, roads, resorts, etc., controlled burns are difficult if not impossible.

Description: There are two generally described phenotypes related to L. occidentale. However, these are not unique enough phenotypically or genotypically to be considered separate subspecies. The taxonomic classification has not changed since it was described by Prudy in 1897.

The existence of the two forms of Lilium occidentale are taxonomically distinct and not disputed. In general, the “California” form is more likely to be found on mineral-based soils with either a clayey subsurface horizon or iron pan that serves to impede drainage (Imper 1997). This form is characterized by wider leaves, a greater degree of whirling in the leaf arrangement, a taller height, lighter neon-red flowers, with a larger yellow star-shaped pattern, and multiple flowers (up to 30), all of which are characteristics more typical of L. columbianum.

Typical classic Oregon form (Hansen)

The “Oregon” form is more likely to be found in fen habitat with deep organic peat or muck soils (Imper 1997). This form typically has narrower leaves, exhibits little or no whirling, may be shorter, and with fewer flowers, dark brick-red flowers, and very distinct yellow star pattern, and lime green star-shaped center, more characteristic of L. pardilinum ssp. vollmeri. However, no overt evidence of hybridization between L. occidentale and L. pardilinum ssp. vollmeri has been reported in the literature or observed (Imper, unpub. data 2008). And the two species have never been observed co-existing in the same proximity or habitat.

Although the two phenotypes do intermingle with each other towards the central area of the L. occideantle’s range, the distinction of the two varieties “California” and “Oregon” appears in large part correlates with differences in environment.

L. occidentale typical classic California form (Hansen)

A genetics study (U.S. Fish & Wildlife) in 2006 investigated the genetic structure of Lilium occidentale. The study tested 492 individuals from across the entire known range of the lily and concluded that populations that were in close proximity to each other had moderate levels of genetic similarity than distant populations, as would be expected. The study found no significant evidence to suggest that separate genetic subgroups existed. But it also noted that within several populations there was evidence that several (two or three) genetic ‘microgroups’ may be present in several of the groups sampled. But the genetic variation was minimal and within the accepted degree of variance, and was not significant enough to suggest distinct subgroups.

The study looked at other lily species from similar habitats shared with L. occidentale and concluded that although the Lilium occidentale, L. pardilinum ssp. vollmeri, and L. columbianum appear to be genetically similar, having similar levels of genetic diversity and sharing alleles (different forms of a particular allele) at all allele loci. Genetically, L. occidentale appears to have no common ancestor with other Western American lilies (DeWoody and Hipkins (2006)). L. occidentale is a genetically unique species unrelated to any other Western American lilies.

L. occidentale x. L. columbianum natural hybrid (Hansen)

The study concluded that although hybridization with other Lilium species, almost entirely L. columbianum, has occurred for nearly a century or more, and continues to occur across the range, there is no evidence that the genetic intermingling poses an immediate threat to L. occidentale. The species is genetically unique with good genetic integrity, and genetically similar across its entire range.

A naturally occurring mutation among otherwise typical specimens. The hyper-pigmentation of the central region is not unique to L. occidentale, and is also seen in other Western American lilies. (Hansen)

There are mutations of L. occidentale that occur naturally. One such mutation, that also appears in other Western American lilies, is a melanistic, or hyper-pigmentation, of the spotting in the central area. This mutation is seen in other lilies as well, notably L. columbianum and in at least one area with L. kellogii as well.

Cultivation: In cultivation, plants flower in as little as 3 years (Skinner 1988); in the wild plants may live for 25 years or more (Imper et al. 1987). In cultivation plants may live up to 35-years or more (McRae, Imper & Skinner). Seed should be sown in early fall and will germinate in late fall early winter at 40F (4C). Given its rarity any unique phenotypes should be cloned if possible. When planting choose a site that gets morning sun, but is shaded from hot afternoon sun. The site should be similar to that as chosen for L. pardalinum. A common mistake is over watering in the summer during active growth. This will most likely lead to bulb rot. During the summer keep the lily fairly dry. If growing in pots use more grit and sand with some sphagnum mixed in.

Conclusion: Lilium occidentale is a rare beauty not because of its delicate nature, but because of human activity such as development and suppression of natural wildfires. Where seed can be obtained legally with the permission and documentation of private land owners, great care must be taken to ensure that it has the best possible chance of success in the garden. At no time, should specimens ever be collected from the wild or seed taken from wild populations. Regardless your intent the plant sees you as nothing more than a seed predator, and again, regardless your intent, this is poaching plane and simple. Also, remember L. occidentale is an endangered species and protected under the Endangered Species Act as well as C.I.T.E.S (Convention in Trade of Threatened & Endangered Species) and collecting any material with proper permits from federal, state, and local authorities is a crime. Many populations are monitored with video recording by local and federal law-enforcement. So if you see one, stop and admire it, take some pictures and let it be, and keep in mind, your probably on camera.

L. occidentale in natural habitat (Hansen). Typical or classic L. occidentale (Hansen) SowingTypical or classic L. occidentale (Hansen)NaturalPopulation of L. occidentale in natural habitat (Hansen)Strange phenotype, possibly a natural hybrid (Hansen)A large specimen hidden behind Sitka spruce (Hansen)Large specimen in Sitka spruce stand (Hansen)Typical classic L. occidentale (Hansen)natural L. occidentale x L. columbianum hybrid (Hansen)

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