Leadplant—A Legume and Pollinator-friendly Native Shrub

There are numerous prairie legumes that fix atmospheric nitrogen, such as the prairie clovers and the indigos. Among them is the highly regarded leadplant (Amorpha canescens). If driving along a railroad right-of-way and this distinctive plant is seen, it warrants a closer look. Near this deep-rooted, high-quality prairie species, other prairie plant species are usually found. Thus, it is frequently described as an indicator species for high-quality prairie remnants.

Leadplant is named for its leadened–colored leaves. Also, numerous accounts credit its name to early settlers who thought its growth indicated lead ore underneath the ground where it grew. The blue-gray hues of its leaves are almost the exact color of galena, a sulfite of lead and the principal ore of lead. Early settlers also knew that its roots penetrated deeply into the soil, up to 15 feet or more, thus supposedly having the ability to detect galena deposits. Such assumptions were not true.

Leadplant occurs primarily in the northern two-thirds of Illinois prairies if the habitat is suitable. This plant is nearly absent in southern Illinois. Well-drained black soil prairies, sand prairies, hill prairies, black-oak savannas and high-quality tallgrass prairie remnants on railroad rights-of-ways are some of its favored habitats.

To some, seeing leadplant classed as a shrub is surprising, knowing the plant only as a small 2-foot-tall perennial growing on patches of tallgrass prairie that are routinely burned to preserve their natural quality. Periodic prescribed fire keeps leadplant to a shortened stature, often killing it back to ground level with each prairie burn. However, the roots survive ready to respond during the start of the next growing season.

To see this shrub with taller stature, visit a right-of-way of an abandoned railroad not subjected to fire, herbicide application or mowing. Better yet, go to an unburned hill prairie. There, leadplant reaches heights of 5 feet and more—its true woody shrub character and stature.

Leadplant is a legume as indicated by its pinnately compound leaves. It fixes atmospheric nitrogen on root nodules if native symbiotic rhizobial bacteria is present in the soil. Thus, the soil is enriched. Leadplant grows best when this bacteria is in the soil. Leadplant blooms in early and mid-summer. Its small flowers with yellow stamens are shades of purple and densely aggregated in an inflorescent arrangement.

For added enjoyment for the viewer, leadplant attracts a wide variety of insects, birds and other wildlife, making it a good choice for backyards or other near environments. The flowers attract both long-tongued and short-tongued bees, as well as bumblebees and wasps. Caterpillars of dogface sulphur butterflies feed on the foliage. Other insects feed on the foliage, flowers and seeds, including grasshoppers and leafhoppers. In turn, this plethora of insects attract birds.

The leaves are high in protein and are very palatable, attracting mammals such as deer and rabbits. Thus, a word of caution. These mammals may not be wanted by some homeowners. However, if you have an area in your backyard or near environment with full sunlight for most of the day, consider planting leadplant.

Few are familiar with this plant, even fewer are acquainted with it in its full-shrub stature. Your neighbors will be asking you, “What is that?” and be wanting leadplant as their very own.

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Robert J. Reber is an emeritus faculty member in the Department of Food Science and Human Nutrition of the University of Illinois at Urbana-Champaign. He has been a lifelong student of many aspects of the Natural World, including archaeology. Reber has served as a managing editor and author for publications such as The Illinois Steward and the Illinois Master Naturalist Curriculum Guide.