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.)

Throughout most of modern botanical history this Chinese lily has been known as Lilium tigrinum, but recent nomenclatural reassessment affirms that Thunberg’s description, published sixteen years earlier than Ker Gawler’s, applies to this species. Though many North America species are known vernacularly as tiger lilies, the name is properly applied only to this one. Along with L. candidum, it is considered to be among the earliest domesticated lilies (H. D. Woodcock and W. T. Stearn 1950), no doubt because it is handsome, easy to grow, and the bulbs are edible and substantial. It is widely planted in North America, usually as a sterile triploid that is best propagated from the bulbils.

Perhaps the hardiest garden lily, Lilium lancifolium is a widespread but sporadic garden escape, and roadside lilies near habitation in eastern and northeastern North America are often this species. Despite its general use in gardens, it seems to be naturalized only in the better-watered eastern portion of the continent.

In North America, the tiger lily is rather easily diagnosed by its truly lanceolate and widely sessile alternating leaves that bear dark bulbils on the upper stem. The mature buds are usually high-shouldered and taper rather evenly to a flattish apex with three greenish, terminal, rounded processes. No native lily consistently displays any of these features.

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