Madison, WI. On Sunday I went down to the Arboretum’s Wingra Oak Savanna with some friends to show them around the restoration project and to look at the nearby Council Springs, and Dancing Sands Springs. And, of course, to botanize.
One of the highlights on this gorgeous spring day were the carpets of white trout-lily (Erythonium albidum) under the spreading open-grown bur and white oaks that provide the framework for the savanna. The bloodroot (Sanguinaria canadensis) was past and the Jacob’s ladder ( Polemonium reptans) was just that day starting to flower.
There were so many large colonies of white trout-lily at the Wingra Oak Savanna it was hard to take them all in; seemingly everywhere you looked was another patch. But only a few flowering stems of yellow trout-lily were visible.
White trout-lily and its cousin, yellow trout-lily (Erythonium americanum) are true spring ephemerals, meaning they go dormant by late spring or early summer after producing seed, just after the tree canopy closes in. Trout-lilies like moist woods, forests, and apparently savannas. The white variety is more common in southern Wisconsin; the yellow form common in the northern part of the state.
All trout-lilies grow from small underground vertical structures called corms, which are an enlarged, fleshy, solid base of a stem. Each corm sends up two leaves and, usually, a single flower stalk. However, both white and yellow trout-lily are notorious for producing sterile, non-flowering corms which produce dense colonies of single leaves. Truly though, I don’t know what evolutionary advantage there is to a plant being sterile.
The leaves of trout-lilies are shaped like a fish and are mottled or spotted, giving it the appearance of the markings of a brook trout.
Some think the tepals are shaped like a long canine tooth, hence the alternate common name of dog-tooth violet, despite the fact that the plant is not a violet but rather, is in the lily family (Lillaceae). Other common names include Fawn Lily and Adder’s-tongue (Fassett, 1976).
Trout-lilies are clonal species meaning that while a given patch consists of many individual stems, they are all produced by common underground stems or stolons that arise from the mother corm and have an identical genetic makeup. New colonies can be produced by seed.
Research has shown that trout-lily clones can live a long time. Whitford (1951) studied the structure and age of a typical mesic forest stand in Green County, Wisconsin. He determined “that the average age of a trout-lily colony was 145 years, ranging from 40 to 313 years.” (Curtis, 1959.) This upper age estimate was just six years after the explorer Nicolet in 1636 visited what would become Wisconsin.
Curtis, J.T. 1959. The Vegetation of Wisconsin. University of Wisconsin Press. Madison, WI.
Fassett, N. C. 1976. Spring Flora of Wisconsin. University of Wisconsin Press, Madison, WI.
Whitford, P.W. 1951. Estimation of the age of forest stands in the prairie-forest border region. PhD thesis, University of Wisconsin-Madison.