by Steve Sass and Amanda Smith, Indiana Nature LLC.
A familiar sight in the dunes this month is the whiteish-blue flowers of wild lupine (Lupinus perennis). Not only is this native perennial plant beautiful, but its existence also plays a critical role in the ecology of northern Indiana.
Upon first glance, you might notice that that the flowers of wild lupine resemble those that you have seen elsewhere, and if you take a close look, you will see that the flowers are “irregular,” with each containing five petals. The two symmetrical top petals are known as the “banners,” the two smaller, lower petals known as the “wings,” and the lowest petal as the “keel.” This flower structure is distinctive of the Fabaceae (pea) family of plants.
Fabaceae is a large family of plants with over 13,000 species worldwide. Based on the flowers, can you think of other members of the family? You needn’t travel far to find them. Aside from the garden pea, beans are also in this family of plants as are the wild indigos (Baptisia spp.), honey locust (Gleditsia triacanthos), and eastern redbud (Cercis canadensis) trees, and even the common lawn clovers (Trifolium spp.). If you visit wild lupine in a few weeks, you’ll find its fruit contained in pea-like pods, which is another characteristic of the Fabaceae family.
The leaves of Lupinus perinnis are distinctive. Palmately compound and comprised of 7-12 leaflets, they somewhat resemble the hours on a clock. That, coupled with the leave’s tendencies of orientating themselves to face the sun, is the inspiration for another one of its common names, “sundial lupine.”
Over 150 species of Lupines are native to North America, but only six of them are native east of the Mississippi, and of those six, only one (Lupinus perennis) is native to the Midwest. In Indiana, it occurs naturally only in the northern part, particularly in the dunes and sandy savannas of the northwest.
Numerous bees and flies pollinate wild lupine, but since the flowers lack nectar, pollen is their only reward. However, Lupinus perennis is an ecologically significant plant for a different reason. Its foliage is a larval food source to at least six species moths, two skippers, and three butterflies, all three of which are noteworthy.
The caterpillars of the Karner blue butterfly (Lycaeides melissa samuelis) are extreme specialists, able to eat only one thing, the foliage of Lupinus perennis, which severely impacts the butterfly’s range and ability to adapt to changing conditions. For years, this federally endangered butterfly was one of the faces of conservation in the Indiana Dunes. Unfortunately, the warm, dry spring and summer of 2012 further disrupted the ecological balance of the butterfly and its food source. As a result, ecologists now consider the Karner blue butterfly extirpated from Indiana.
Butterfly enthusiasts who travel a bit to the south at the right time might be lucky enough to observe another wild lupine specialist, the frosted elfin (Callophrys irus). In recent years, the only Indiana sightings of this State Endangered, and Globally Imperiled butterfly have come from an oak savannah in Starke County. A third butterfly that is a lupine specialist, the silvery blue (Glaucopsyche lygdamus), had gone unreported in Indiana from the 1980s until 2019 when an observer spotted one in LaGrange County.
Habitat destruction and fire suppression have resulted in a decline in populations of wild lupine. Subsequently, the animals who depend on it for survival have also steeply declined. As you explore the dunes this spring, pause to admire not only the beauty of wild lupine but also its essential role in our ecosystem.
Did you enjoy this article? Be sure to check out Steve and Amanda’s facebook group, IN Nature.
Are you a lover of Lupine? Check out our “Stop and Smell the Lupines” t-shirt, (right here) illustrated by local artist Mark Coleman!