An especially important plant in the early stages of recovery was Lupinus lepidus, prairie lupine, a purple- and blue-flowered legume that took root even on the Pumice Plain. Lupine plants have nodules in their roots that contain nitrogen-fixing bacteria, so they do not have to draw nitrogen from the soil and can grow almost anywhere. Soon vast fields of purple flowers appeared on the blasted plains and hillsides. The individual lupine plants around Mount St. Helens generally died within a few years, after which they provided organic material for other plants.
