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Wisconsin Plant of the Week

Erythronium americanum Ker Gawl.

Liliaceae (Lily Family)

Common Name:

yellow trout lily, dog-tooth violet


Yellow trout lily is an early spring blooming native that grows to 15 cm tall in the partial shade of rich moist woods. It, and a similar Wisconsin species, E. albidum (white trout lily), are easily recognized by extensive patches of lance-shaped leaves with brown or purple mottles. The mottling, which fades on dry specimens, gives the plant its common name since it resembles the underside of a trout.  The genus Erythronium has about 15 species, most of which are confined to North America.

Each flowering plant produces a single nodding yellow flower, 2 to 5 cm across.   Flowers bloom from mid-April to early May.  On sunny days, once the stigmatic surface is receptive, the petals open fully and are recurved. Like most members of the lily family the flowers have 6 tepals (3 petals and 3 sepals), 6 stamens and 3 stigmas. The fruit is a capsule.

Each plant grows from a corm -- an enlaregd portion of the stem that stores starch -- 6 to 10 cm below ground. The leaves are in the middle of the stem, but because the corm is so deep, the leaves may appear basal. The shape of the corm resembles a canine tooth, which led to the name “Dog-tooth violet”.

Trout lilies spread by seed (ant pollinated) and vegetatively by offshoots from the corms.  Only plants with 2 leaves produce flowers and most colonies are mostly single leafed plants. Plants from seed take between 4 and 7 years to flower.

Trout lilies retain mineral nitrogen released during snow melt and have low C:N ratios. Like other low C:N plants, they’re preferred by herbivores since they’re easy to digest, and are quickly eradicated when animals such as rabbit or deer become overabundant. 

  • Origin of the name: Erythronium, erythros, Gr., red, for the red flower color in the type species; americanum, of the Americas
  • Range:  Eastern US from MN to AK and eastward
  • WI Range:  In rich woods mostly northern, south to Sauk County, and along Lake Michigan to Racine County
  • Common associates: Sugar maple, beech, trillium
  • Wetland Indicator Status: UPL
  • Coefficient of Conservatism: C = 8 (S&W), C = 5 (MI)
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