Saturday, April 28, 2012

Wild Ginger

This brownish-purple flower is wild ginger, which is in bloom right now. There are several species commonly called "wild ginger," but the one native to the eastern United States is Asarum canadense, also known as Canadian snakeroot. The common name refers to the rhizomes, which have a ginger-like scent and were used by early Americans as a substitute for ginger in cooking.

Wild ginger is easy to miss unless you know what to look for. The leaves are large and heart-shaped and grow on hairy stems. The flowers are hidden at the bases of the stems underneath those large leaves. Some flowers rest on the ground or on leaf litter. Wild ginger grows in dense, spreading clumps, so the only way to see the flowers is to push the leaves aside. Here is a line drawing of the principal parts.

The position and color of the flower seem designed to attract the attention of flies that feed on carrion. To a newly-emerged fly, the purplish lump lying on the ground may look like meat. (I did not detect any carrion-like odor, though.) The flies then pollinate the plant as they feed on its pollen. The position also serves to attract ants, which carry off the seeds and thus propagate the plant. Since wild ginger is in the pipevine family, Aristolochiaceae, it serves as an alternative host plant for Pipevine Swallowtail (Battus philenor) if pipevine (Aristolochia sp.) is not available.

As you might expect from a member of the pipevine family, wild ginger contains a toxin, in this case aristolochic acid. Whether it is present in sufficient quantity to avoid consumption of this plant seems to be a matter of disagreement. However, it is probably best to use caution, especially since the leaves may cause dermatitis in people who are allergic to them.