Erythronium americanum Ker

Erythronium americanum
Erythronium americanum, Fawn Lily
Erythronium americanum, Fawn Lily

Photograph by John Pickering

common names: Yellow Trout-Lily, Dog-Toothed Violet, Fawn Lily,
Adder's Tongue



CLASS: Liliatae -or- Angiospermae
SUBCLASS: Liliidae -or- Monocotyledoneae
ORDER: Liliales
FAMILY: Lileaceae
GENUS SPECIES: Erythronium americanum


The Genus Erythronium was first described by Carl Linnaeus (1707-1778). The species E. americanum was described by John Bellenden Ker-Gawler (1764-1842).

Erythronium americanum is a "perrennial spring ephemeral that emerges in early April and senesces by mid-May" (Wein, 241). The flower is made up on six yellow tepals which have small purple or brown spots towards the center. The tepals are reflexed and the flower is most likely nodding. The fruit produced is a dehiscent capsule that contain many large seeds (Harder, 288). There are six stamen in two whorls and the anthers are yellow and purple. The flowering individuals have two basal, fleshy, green leaves mottled with purple. There is also a vegital form of E. americanum that does not flower. These individuals make up about 99% of a given population of this species. The distinguishing characteristic of the vegital plants are a single basal leaf and no flower (Wein, 242). Seeds of E. americanum are reddish brown and crescent shaped (Radford, 307).

This species was first described by Ker in The Botanical Magazine, which is now known as Curtis's Botanical Magazine. The magazine was first published in 1790. *Due to its age and rarity, I was unable to find his description of the plant in paper form, but it was published while John Sims was the editor. He held this office from the magazine's 28th volume until after Ker's death, so the description must be between the 28th and 70th volume. The Index Kewensis was very vague on the description's location, but it also read "t. 1113 - Am. bor." after the magazine name. Perhaps someone after me will be able to decipher what this means in their attempts to find the location of Ker's description.*

Erythronium americanum can be distinguished by using the dichotymous key in The Vascular Flora of the Carolinas by Radford, Ahles and Bells. For easier reference, a description of the family Liliaceae can be found on page 281 and the genus and species Erythronium americanum on pages 306 - 308.


Distribution and Abundance Table

Location Status Reference
North America yes Wein and Pickett
Eastern North America yes Wein and Pickett
Southeastern United States yes Rickett
Southern Appalachian States yes Harder, Thomas and Cruzan
Coastal Plains rare Radford, Ahles and Bell
Piedmont rare Radford, Ahles and Bell
Blue Ridge Mountains yes Univ. of Tenn. - Vascular Atlas
Ridge and Valley yes Univ. of Tenn. - Vascular Atlas
Cumberland Plateau yes Univ. of Tenn. - Vascular Atlas
Georgia yes Radford, Ahles and Bell
Clark County doubtful UGA Herbarium Staff

Erythronium americanum thrives in alluvial woods, coves and moist woodlands as far north as Nova Scotia and Minnesota and as far south as Florida and Alabama. It prefers rich low ground near creeks or swamps (Rickett) and can often be found in large cohorts.


The reddish brown seeds of E. americanum have an elaiosome, which is an ideal structure for ant dispersal (Wein, 244). The seed, once dispersed, will produce a radicle around November and will complete germination by late March. The flower will bloom around this time and produce pollen in two phases. This "temporal separation of pollen presentation in the two anther whorls of Erythronium will tend to reduce the chance of a single bee removing nearly all of a flower's pollen. ... Extended dehiscent periods of sets of anthers ... may reflect selection favoring pollen donations to a diversity of vectors" (Harder, 289). In addition to this form of cross-fertilization, there is evidence to assume that the plant may self-fertilize itself by closing up its tepals at night and therefore transfer pollen to the female portion of the flower (Harder, 291).

Near the middle of May, the flower will die off. If fertilization took place, a dehiscent capsule containing many large seeds will be formed. The seeds may again be dispersed by ants or other environmental factors. The now-dead flower will leave a subterranian bulb that will lie dormant throughout most of the winter. The next spring, the bulb will likely play a vegital role in the Erythronium population. In the vegetal form, distinguished in the IDENTIFICATION section above, the individual may send out as many as three ramets by way of runners in order to secure the populations holding on the forest floor (Wein, 243).


books and scholarly journals:

*Cronquist, Arthur. The Evaluation and Classification of Flowering Plants. 1968. Houghton Mifflin Company. Boston, Mass.

*Harder, L.D., Thomson, J.D., Cruzan, M.B., and Unnasch, R.S. Sexual Reproduction and Variation in Floral Morphology in an Ephemeral Vernal Lily, Erythronium Americanum. Oecologia. 1985, v. 67 (2), pg. 286 - 291.

*Hooker and Jackson. Index Kewensis: Tomus I, A-J. 1895. Oxford at the Clarendon Press. Oxford, England.

*Radford, Ahles and Bell. 1968. Manual of the Vascular Flora of the Carolinas. University of North Carolina Press; Chapel Hill, N.C.

*Rickett, H.W. 1967. Wildflowers of the United States: The Southeast States. v. II, part I. McGraw - Hill Book Company; New York, N.Y.

*Thomson, J.D. Pollen Transport and Deposition by Bumble Bees in Erythronium: influences of floral nectar and bee grooming. Journal-of-Ecology. 1986. v.74 (2), pg. 329 - 341.

*Walters, D.R. and Keil, D.J. 1996. Vascular Plant Taxonomy: Forth Edition. Kendall/Hunt Publishing Company; Dubuque, Iowa.


*University of California at Berkeley. "True Lilies." Site @

*Cornell University. "The Families of Flowering Plants." Site @

*University of Tennessee - Vascular Atlas. "Erythronium americanum." Site @

author: Nathan O'Neill
Biology Major at Augusta State Univerity
Ecology 3500 - University of Georgia - Summer of 1999.