Erythronium americanum. Despite a vast network of plant parts underground, the Trout Lily offers only a few beautiful blossoms each spring. Trout Lilies form large, sometimes ancient colonies in rich moist soil, often near small woodland streams. Each colony starts with a seed that develops a little corm that grows near the surface and sprouts a leaf. In a year or two, the young corm emits several threadlike “droppers” that burrow down at an angle of about 45 degrees. (Some misguided ones may surface, then dive again — the white “threads” that appear in Trout Lily groves.) At the end of each dropper — several inches lower in the soil and up to 10 inches from the mother — a new corm forms from food sent down the line by the parent. Eventually the link withers away, and the offspring corm sends up a leaf; it makes food to develop a new corm, which in turns sends droppers down even farther the next year. After a few years a sprouted seed may have produced a dozen plants with corms at various depths in the moist earth; after 20 or 30 years, more than a hundred plants form a mat of many mottled leaves. However, only about one percent of the plants in a colony will bloom each year. Some Trout Lily groves can be a century or more old, and their networks of roots, stems and leaves are important in preventing erosion of the forest floor.