This towering forb of the prairies adapts to a range of conditions, blooming with yellow flowers in loose clusters at the ends of wiry, curving stems from mid to late summer. The typically 8-foot-tall plant sports a skirt of enormous, spade-shaped, dark green leaves that position themselves to face the sun. Prairie dock does best in full sun and dry to moist loamy, well-drained soils, but it adapts to clay, rocky, or poor soils in full sun and tolerates a bit of shade. Thought to be one of the longest-lived species of prairie plants, prairie dock settles in with a 12-foot-long tap root and is nearly indestructible when fully mature. It benefits from regular watering during the first year. 
 
Prairie dock is a valuable source of nectar for many species of bees, butterflies, and hummingbirds. Bees use  parts of the plant to construct nests, occasionally choosing to make their home beneath the huge basal leaves. The stems, leaves, and flowers are an important food source for beetles and other insects, but prairie dock powers through the assaults year after year. Injured parts of the plant produce resin, which Native American youngsters once used as a carrot- or pine-flavored chewing gum (Silphium refers to an ancient, extinct North African plant that contained a resinous sap used for medicinal purposes). The species name refers to the turpentine-like odor of the plant. 
 
Silphium, a genus of North American plants in the Asteraceae family, is found mainly in the Central United States. Some members of the genus are called rosinweeds (another name for prairie dock is prairie rosinweed), which have yellow flower heads July-September that resemble sunflowers. An interesting feature of rosinweeds is that the outer florets in the head are fertile and the inner florets are sterile, whereas in sunflowers, the reverse is true. The flowers produce lightweight seeds that spread easily to propagate the plant, and the tap root sometimes sends up new shoots. This tall, narrow plant will bloom after two or three years, after which it may need to be staked in some garden settings.
 
Native habitats include various types of prairies, woodland borders, old fields, and the sides of roads and railroads. Use in the back of the border; wildflower, cottage, and butterfly gardens; or in exposed locations to show off the leaves. Big bluestem and other native grasses are great companion plants, as are meadow rue, ironweed, smooth asters, compass plant, and stiff goldenrod. 
 
Plant Characteristics: 
Grows 6-10' tall and 1-3' wide. 
 
Prefers full sun and tolerates very light shade. 
 
Prefers deep, loamy, well-drained soils and moist to slightly dry conditions. Adapts to poor, rocky, or clay soils.  Tolerates drought. 
 
Flowering stalks divide at the top into panicles of yellow, 2” flower heads and round, green buds. Each head has 15-30 ray florets surrounding yellow disk florets. Blooms mid to late summer, which is later than others in its genus. 
 
Heart-shaped basal leaves with coarsely toothed margins are up to 24” long and 12” wide. Young leaves have shiny, hairless upper surfaces, while older leaves are dull and rough. Upper leaves on stems very small. Greenish-red stems are mostly leafless.
 
Wildlife Value: 
Host to 6 species of Lepidoptera larvae, including wild indigo borer and 5 specialist beetles and wasps. Primarily pollinated by native and honey bees. Hummingbirds, butterflies, and bee flies also visit. Goldfinches and other birds eat the seeds. Rabbits avoid the sandpapery foliage.
 
Medicinal, Edible, and Other Uses: 
Smoke from the plant was used to relieve congestion.
 
Native Americans made tea from the roots.