Silphium terebinthinaceum

Due to an absence of foliage along prairie dock’s sleek, flowering stems, it appears from a distance that the plant’s large yellow blossoms are suspended in midair. At the base of the plant, huge, spade-shaped leaves add to an overall look that is truly remarkable. Rather than sprawl outward, the leaves stand up with their edges aligned along a north-south axis. In this way the leaf’s surfaces receive a maximum amount of light from the sun as it moves from east to west across the sky.

As with other plants in the Asteraceae family, what appears to be prairie dock’s flower is in fact a flower cluster, or “flowerhead,” consisting of petal-like ray flowers which encircle a group of diminutive disk flowers. Prairie dock attracts a variety of floral visitors – from bee flies to hummingbirds – and owing to the narrow tubular shape of its disk flowers, long-tongued pollinators like bumblebees have favored access. Prairie dock’s seeds are consumed by goldfinches, and these and other songbirds utilize the plant’s tall stems as a place to perch.

Growing best in full sun, this native of NE Ohio meadows tolerates a wide range of soil moisture, from moderately wet to moderately dry, and is well known for having excellent drought tolerance. A very long-lived plant, prairie dock blooms for approximately one month in late summer and will do so for many years.

Due to their impressive height (up to 10’), the plant’s flowering stalks sometimes have a tendency to lean, especially in windy areas. This can be remedied by cutting the stalks down to the base of the plant in early July, when they are about 2-3 feet tall. The stalks will then regrow to a height of approximately 4 feet and will be resistant to leaning and getting blown over. Plants treated in this manner will then bloom at the usual time for this species, i.e., late August.

References: 1,2,3,4,5.

Photos by Ashley Keesling.