Lilium washingtonianum

Kellogg 1859

Washington's lily

Lilium washingtonianum purpurescens (Mt. Hood lily) Mt. Hood, Oregon (Hansen)


  • Section: Pseudolirium (North America)
  • Origin: United States, western mountain ranges (Cascade, Siskiyou, Klamath, and Sierra Nevada mountains)
  • Habitat: volcanic soils, forest edges and coniferous forests in full sun to heavy shade.
  • Type: American dryland
  • Status: Common

Introduction: Washington's lily is named for Martha Washington, the wife of the first President of the United States (McRae 1998). There are currently two recognized subspecies. The standard or typical form Lilium washingtonianum washingtonianum occurs from northern California at the foothills of the Sierra Nevada mountains and extends south along the mountain range to Yosemite National Park. Subspecies Lilium washingtonianum purpurescens (Stearn 1948), often called the 'Mt. Hood lily', occurs from the northern extreme end of the lilies range from the Klamath mountains in northern California and southern Oregon to the 'Mighty' Columbia River. Its subspecies nomenclature, purpurescens, means 'to turn purple' Finally, a former subspecies Lilium washingtonianum minus (formerly Lilium washingtonianum shastense) (Purdy 1919) only occurs around Mt. Shasta, as you might have deduced, and is often called the 'Shasta lily'. It is now considered synonymous with Lilium washingtonianum washingtonianum.

The standard type, Lilium washingtonianum washingtonianum, occurs from Shasta county south to Fresno county, California. It occurs almost exclusively in the Sierra Nevada mountains, east of the Klamath mountains. The ranges of the two types does overlap some near the Oregon-California border, though generally Lilium washingtonianum washingtonianum occurs further east of the subtype purpurescens which is more westerly along the coast and doesn't appear to extend east of the Klamath mountains.

Subspecies purpurescens occurs from the Columbia river along the Washington-Oregon border, to the Klamath mountains in Southern Oregon and northern California. Subtype minus (shastense) occurs in Shasta county, California at the base, and around Mt. Shasta.

Lilium washingtonianum purpurescens (Mt. Hood lily), Mt. Hood, Oregon (Hansen)

Description: The taxonomic characteristics of all three types are very uniform. The bulb is sub-rhizomatous and white. It can get quite large in older specimens. It resents transplanting and often rots if dug. The stem rises 3-7 feet (120-200cm) with light green broad-lanceolate leaves in whorls. The inflorescences is a raceme of 1-30 flowers, that open white with light purple spotting. The pollen is lemon yellow on semi-spreading anthers. Bloom-time varies depending on altitude and geographic location, but is usualy from mid May to July. The flower is an outfacing trumpet type that opens white, that depending on subtype, fade to lavender purple. The flowers have a intense intoxicating spicy fragrance. Primary pollinators are hawk moths.

There are two recognized types with the third, Lilium washingtonianum minus, now being synonymous with Lilium washingtonianum washingtonianum. The types are:

  • Lilium washingtonianum washingtonianum
  • Lilium washingtonianum minus (syn. Lilium washingtonianum washingtonianum)
  • Lilium washingtonianum purpurescens

The typical type Lilium washingtonianum washingtonianum, is found almost exclusively in the Sierra Nevada mountains of California from Shasta county to Yosemite National Park and represents the southern extent of the species distribution. It is in all respects identical to the subtype Lilium washingtonianum purpurencens except the flowers do not fade to white as they age. Former subtype Lilium washingtonianum minus is found at the southern end of the Cascade mountains around Mt. Shasta and may represent the extreme range of the typical type, or if it has any unique characteristics may represent either a geographically isolated population, or a population that represents a cross between the two types at their most extreme ranges.

Subtype Lilium washingtonianum purpurencens, the 'Mt. Hood' lily, is found almost exclusively in the Klamath mountains and Cascade mountains of the Pacific Northwest all the way to the Columbia river on the Oregon-Washington border, with a few specimens reported in Washington in the Columbia river gorge. As its nomenclature suggests, the biggest difference besides distribution, is it's flowers turn purple as they age. Hence, purpurencens 'to turn purple'.

ThisLilium washingtonianum purpurencens growing among Rhodendron macrophyllum. Mt. Hood, Oregon (Hansen)

Habitat: Washingtonianum is a typical Western American dryland lily inhabiting mid to high sub-alpine habitats from roughly 1,500 feet (460m) to 4,000 feet (1,220m) in deep volcanic porphyritic soils of andesitic and basaltic rocks of late Pleistocene origin. These soils have moderate to excellent permeability.

Washingtonianum inhabits volcanic soils that have formed over millions of years in the Western Mountain Regions that include the Cascade, Klamath, Siskiyou, and Sierra Nevada mountains and their related volcanic complexes. These mountain ranges and their related volcanic centers originated millions years ago as the North American plate moved east. While the younger Cascade mountains and it's numerous volcanos form the Cascade volcanic arc are classic subduction zone volcanoes, others like the Klamath mountains of Northern California began as a series of volcanic island arcs. As these volcanic centers formed, sediments were repeatedly uplifted, folded, and mixed with the granites of the ancient seafloor bedrock. Intruding into this mixture are large geological masses and volcanic intrusions that formed under extreme pressure in the earth's interior. Because of the manner of their formation, these rocks are deficient in some minerals (such as calcium and potassium) and are heavily abundant with others (such as magnesium, iron, and nickel).

For example, the soils at Mt. Hood are generally of the Mt. Hood, and Parkdale series. They consist of volcanic soils that formed in lahars and pyroclastic flows, and are very deep, well-drained soils. These soils are usually moist and are dry between depths of 8-24 inches (20-60cm) for 45-60-days during the summer. The mean annual soil temperature is 47F (8C)-51F (10C). The soils are slightly acid to neutral.

Lilium washingtonianum purpurencens (Mt. Hood lily) Mt. Hood, Oregon (Hansen)

It grows in disturbed areas, along road ditches and banks, as well as forested woodlands, in full sun and heavy shade. It frequently populates steep road banks where it's nothing but deep road and volcanic scree, steep streambanks, and mountain slopes, as well as flat areas usually with Rhododendron macrophyllum, often growing side-by-side. It frequently shares habitat with L. columbianum. In many areas the the two species grow interspersed or within just a few feet of each other. Though they do not produce any known natural hybrids. It is interesting that deer will readily graze L. washingtonianum, but otherwise leave L. columbianum alone. The reason for this is unknown at this time. But could be that the plant has an unappetizing taste.

Climate: The climate of the American Western Mountain Regions varies greatly from north to south but follows a similar overarching trend of high daytime temperatures and low nighttime temperatures. This is a key factor throughout the North American western mountain regions. The same overarching trend holds true for precipitation as well, with the majority occurring in the fall and winter (wet season), and abruptly falling off by as much as 80-90% in the summer (July-September). Snow is also a key factor as will be discussed later.

The climate is characterized by Pacific High Pressure Zone which brings predictable dry, hot summers, and humid, cool wet winters. The mean annual precipitation ranges from 90-125 inches (230-300mm); mean fall (November-January) precipitation is 13-inches (330mm); mean summer (July-August) precipitation is 2-inches (50mm). The mean annual temperature ranges from a high of 50F (10C) to a low of 33F (1C); the mean winter (January-March) temperature is 25F (-3C); and the mean summer temperature is 66F (18C). Mean snowfall is 267-inches (678cm). The growing season is less than 50-days.

It is also important to note, that though precipitation varies radically across the western mountain regions of the American West Coast, the rain shadow effect plays a monumental role where Western American lilies grow. On the east side of the mountains are the arid regions with less than 20-inches per year. On the western Pacific facing slopes are soaking wet temperate rainforests that average over 100-inches (250cm) of rain a year. L. washingtonianum, like all Western American lilies does not (usually) occur east of the divide of these mountain ranges (though there will always be some lilies that didn't get that memo, and a few will wander a bit east, but by in large, they do not grow east of the divide.)

This trend can be seen, agian, by using the subspecies Lilium washingtonianum purpurescens around Mt. Hood, a high alpine environment, at the far northern end of the lily's range on the southern bank of the Columbia river as an example. Here at Mt. Hood, the mean annual temperature is about 47F (8C). The average winter temperature (January-March) is 28F (-2C), average summer daytime temperature is 80F (27C), and nighttime temperature is 46F (7C). This is an important note to make that applies to most Western American lilies, especially dryland lilies, that though the daytime temperature may be high, in the 90F-100F (32C-37C), nights cool off dramatically to usually at least the 60F (15C) if not cooler. The drop of almost 34F (20C) between day-time and night-time temperatures is difficult to recreate in most locations, but is a must for American dryland species. This temperature flux plays a vital function in how the lilies regulate internal temperature and metabolize nutrients and synthesize proteins.

Moisture regimes are very important and are one of the critical variables that determines where a species can grow. At Mt. Hood the mean annual precipitation is 42-inches (106cm). The mean winter (January-March) precipitation is 4.2-inches (106mm). Mean summer (July-September) precipitation is 0.5-inches (12mm). There's an 84% decrease in precipitation from the wet season to the dry season. The vast majority of the precipitation occurs from November to February. Mean snowfall (December-March) is 14-inches (355mm). Though these statistics are for Mt. Hood at the far northern end of the lily's habitat, it serves as an excellent example of the overall trend through the American Western mountainous region, and makes it clear as to what climate factors washingtonianum and, its dryland relatives, require.

L. washingtonianum (Hansen)

General information: Washingtonianum is a true American dryland lily. I've seen it growing all over Oregon, and California (and there are a few that grow just across the Columbia river in Washington in the Columbia river Gorge). It grows in very similar habitats in all locations. It's often seen growing with L. rubescens, L. bolanderi, L. columbianum, L. pardalinum, and other western American lilies. The ranges of all these lilies overlap to varying degrees, and it's not uncommon to see L. pardalinum in a wet meadow or along a stream bank and L. washingtonianum just a few feet away up on a dry slope or road cut. It grows interspersed with, or just feet from, L. columbianum in many locations.

A fasciated stem of Lilium washingtonianum purpurencens in a garden in Parkdale, Oregon. (Hansen)

Cultivation: washingtonianum is not impossible to grow. It's actually a rather easy lily to grow from seed as long as you understand it resents being coddled or pampered. It's a tough as nails no fuss lily. The best approach is to sow seed in a tray of grit or scree with lots of fire ash and set it aside. Or choose an area of the garden that is left alone. It wants class-A drainage. Like all American dry-land species it detests fertilizer (phosphorus in particular). It's a fire-chaser like most American lilies, so lots of fire ash and volcanic supplements like Azomite is beneficial. But supplements with phosphorus will absolutely kill it. Beyond that just let it be and in a few years (a decade or so) it will reward you well.

During the summer it wants virtually bone-dry conditions. That doesn't mean it doesn't want water. The western mountains of the U.S. are very hot and dry in the summer, but frequent thunderstorms can drop as much as an inch or more of rain in minutes. The issue then is obviously drainage. These lilies grow in very rocky soils that drain quickly. These soils are not compact as you might think but very porous to allow FAE (fresh air exchange) so that the bulb dries quickly and the moisture in the soil and the air flow provide natural AC (air conditioning) to cool the bulb in the otherwise hot environment. Despite the summer heat, mean annual soil temp is 50F (10C).

Eddie McRae use to go out to the road in Parkdale, Oregon and shovel up road scree into pots. He'd sow seed of Western American dryland species (washingtonianum, bolanderi, kellogii, etc.) in them. Then he'd set them out of the way and let Mother Nature do the rest. He grew pots of gorgeous stems that would be the envy of every hortophile. It was a joke that when people would ask how he grew such neurotic liliy species like American dryland lilies, he'd say - Nothing at all. Whatever the road department laid down and he could shovel up. Then he just let them be off somewhere out of sight and mind. I don't think anyone believed him but I can tell you it was absolutely true. Eddie always said people literally love their lilies to death. He was an advocate of less is better, hands off, let them be and they'll be just fine. Like a master wine maker, the key to making a great wine isn't telling the wine what it's going to be. It's listening to the grapes and letting them tell you how it's going to be. And trying your damnedest to not get in the way and screw it all up. The same is true for lily species, especially dryland species.

It readily populates orchards, growing between the trees and along the edges of the fields. I've seen hundreds growing in fruit orchards in Parkdale, Oregon between the rows of trees. The owners say they don't do a thing except mow and maintain the trees. The lilies are just an added bonus they say. Where it becomes established it can last for decades and form huge populations. Eddie McRae and I visited a homeowner in Dee, Oregon who had literally hundreds in her front yard. According to her she did nothing special other then mow in late winter or early spring before the lilies emerged to keep the grass manageable, then left the lilies alone unitl fall when the stems turned brown. Then she mowed again to clean it up. It was truly an amazing sight to see. I wish I had pictures.

I performed an experiment in 2011 by sowing 50-seeds of washingtonianum at Mt. St. Helens in Washington state. Most of the seeds germinated the first year. But 10 years later only three have survived and none are of flowering size. The same year I also sowed several hundred seeds at Lava nursery at the base of Mt. Hood in a small secluded wooded area where other native washingtonianum were growing. I marked the location with stakes and have been monitoring both locations every year since. They show the same results. Only a small handful of seedlings remain after 10-years, and none are blooming size. This suggests that wild blooming plants must be at least 10-years old or older. Another reason why wild plants must never under any circumstances be dug. We also sowed seeds in flats and then put them aside and let Mother Nature do the rest. They show the same trend of slow annual growth, but have a much better attrition rate than the seeds sown in the wooded areas, as would be expected.

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