Friday, April 18, 2008

Myrmecochory: Trout Lily

Trout Lilies (Erythronium americanum) are a beautiful spring wildflower that dot the forest landscape with bright yellow blossoms. Their common name comes from the leaf which is covered with brown spots like the speckled body of a trout. Another common name for it is Adder's Tongue.

A nice grouping of the Trout Lilies at Southeastway Park
Below is a close-up of the leaf, with its crude fish-shape and brown speckles like that of a trout.

Trout Lily leaf
The Trout Lilies blossom has delicate sunny yellow petals that gently curl back exposing the anthers. Each flower has six tepals, comprised of three petals and three sepals. The petals are entirely yellow, while the sepals are yellow on the front and brownish on the back. The flower will close each evening and open up in the warm morning sun. A trout lily may take as many as seven years to become a mature plant from a seed. Only plants with two leaves will flower that year.

Trout Lily with its gorgeous yellow blossom

What is most fascinating about the Trout Lily is its seeds are dispersed by ants, a process called myrmecochory. The seeds have a fleshy structure attached to the outside of the seed called an elaiosome. The elaiosome is rich in oils that contain lipids and proteins. The ants will carry the seed to their nest to feed the larvae the elaiosome. The seed is then discarded in their waste pile which is rich in nutrients for the seed. This symbiotic relationship benefits the ant in the form of food, but it also benefits the plant as well. The seed is dispersed to limit competition, but it is also protected from rodents who would most likely eat the seed if it was left under the plant. Also, the seed is placed in a nutrient rich area in the ants nest, giving it a great head start. Other plants that have elaiosomes are Wild Ginger, Bloodroot, Dutchman's breeches, and Twinleaf.

An ant dragging a seed by the elaiosome. Photo from Northwoods Wiki.

A close relative of the Trout Lily is the White Fawn Lily(Erythronium albidum) or Dogtooth Violet. It looks just like the Trout Lily, but its tepals are white.

White Fawn Lily

The intricate workings of nature have always been intriguing to me. Hopefully you will be lucky enough to witness an ant carrying its elaiosome this spring! I know I will be watching for them.


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