Flora of North America species comparison

The narrowly endemic Gray’s lily blooms predictably on or about July 4 in the balds and forest openings of the Roan Mountain massif shared by North Carolina and Tennessee. In its unadulterated form it also occupies the higher elevations of the Blue Ridge Mountains, including Grandfather Mountain in North Carolina and Mount Rogers and Whitetop Mountain in Virginia. A few populations occur at lower elevations (below 900 m) in streamside meadows along the Blue Ridge Parkway in northern North Carolina (Alleghany County), but in similar settings farther north in Virginia introgression with L. canadense occurs.

Lilium ×pseudograyi Grove (as species) is a name given to frequent hybrids between L. grayi and L. canadense that are scattered at somewhat lower elevations (usually 700–1000 m) in the southern Appalachians. The generally small stature of these hybrids is misleading and encourages the label of bona fide L. grayi, but in most respects they are intermediate. Sepal lengths of 4.8–6.2 cm and floral tube lengths of 3.2–4 cm predominate, and these are between the ranges of the two parent species. The freshwater wetland or moist hardwood habitat of these hybrids also reveals the contribution of L. canadense to their genome.

J. K. Small (1933) made reference to depredations by lily enthusiasts who sought Gray’s lily because of its supposed rarity, and this continues today, though to a lesser degree. Of greater threat, perhaps, is succession on the high grassy balds that gradually shades and crowds the plants; like most lilies, this one requires open conditions for vigor and reproduction.

Although fritillaries (Speyeria spp., family Nymphalidae) pilfer nectar from flowers of Gray’s lily, ruby-throated hummingbirds [Archilochus colubris (Linnaeus), family Trochilidae] are its only reliable pollinator. This red, tubular-flowered lily represents the zenith of pollinator-mediated evolution in the eastern true lilies, and is a high-elevation derivative of the ancestral stock that also produced Lilium canadense. The level of floral convergence with independently derived western Lilium species such as L. bolanderi and L. maritimum is remarkable and must be due to selection pressures exerted by hummingbirds during the floral evolution of these species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

In the late nineteenth century, botanist and bulb merchant Carl Purdy employed Native Americans to collect bulbs of lilies and other desirable plants in the area around Eureka, California, and Lilium occidentale was among the species he was brought. After Purdy described Lilium occidentale in 1897, the plant came into great demand. He later (C. Purdy 1937) lamented that almost no plants were available for cultivation. Populations fluctuated in the middle of the twentieth century and frequently declined dramatically from overcollecting following publicity that the plants had recovered and flowered. Much habitat was subsequently lost to ecological succession and land conversion. Fortunately, several large populations have recently been discovered near Crescent City, California, and completion of a recovery plan (Fish and Wildlife Service 1998) bodes well for the future of this state and federally protected plant.

Lilium occidentale occurs in scattered populations from Humboldt Bay, California, to Coos Bay, Oregon, always within six kilometers of the ocean. Plants near Humboldt Bay occur in coastal prairies and scrub, whereas many Oregon populations are found in sphagnum bogs. Typical Oregon and extreme northern California plants in the vicinity of Crescent City (Del Norte County) have an irregular bulb that occasionally is nearly erect (0.3–0.7 times taller than long versus 0.3–0.5 in Humboldt Bay plants). In northern plants the leaves are often scattered—though they are whorled in larger plants—and extremely long and thin [4.2–26.3 × 0.4–2.7 cm (4.6–28.6 times longer than wide) versus blade 4.1–18.9 × 0.7–3 cm (4–17.4 times longer than wide)] in Humboldt Bay plants. Flowers of Oregon plants are marginally smaller, have somewhat narrower sepals (4.4–7.6 × 0.8–1.5 cm) than Humboldt Bay plants (4.4–8.1 × 1–1.8 cm), and typically appear somewhat later. These differences have provoked discussion about the merits of subdividing this species, but many of the differences appear to be related to habitat rather than genotype. For example, plants from Shores Acres State Park in Coos County, Oregon, occur in a coastal bluff setting that is similar to habitats near Humboldt Bay, and these lilies share many of the same vegetative and floral characteristics of Humboldt Bay plants. Subspecific differentiation appears to be unwarranted.

Lilium occidentale is distinguished from similar species such as L. pardalinum by the closely parallel stamens and adaxial green star formed by the conspicuously green sepal and petal bases, a characteristic also discernible in the abaxial surface of the buds. This green star is present in nearly all flowers when first opened, but changes to yellow or yellow-orange as the flowers age. The green star of certain eastern taxa (e.g., L. superbum) is also diagnostic for them but is primarily formed by glossy green adaxial nectaries and is not so prominent in bud.

Frequent hybrids with Lilium columbianum in Oregon occur primarily where human disturbance has introduced that species into boggy areas via drier open pathways such as powerline right of ways and roads.

With the likely exception of Lilium canadense, L. occidentale is the only North American pendent lily that is pollinated almost exclusively by hummingbirds (in California primarily the Allen’s hummingbird [Selasphorus sassin (Lesson), family Trochilidae]). Its pendent red flower is transitional between butterfly-pollinated forms like L. pardalinum and the classical bird-adapted flowers of L. maritimum and L. bolanderi that are more tubular and horizontal.

The Karok ate Lilium occidentale bulbs after baking them in an earth oven (D. E. Moerman 1986).

(Discussion copyrighted by Flora of North America; reprinted with permission.)