Before Bleeding Heartland’s wildflower series goes on winter break, let’s revisit a late summer bloomer. Today’s featured plant is one of four native species in the Silphium branch of the aster family. (The others, which also have yellow composite flowers, are cup plant, compass plant, and rosinweed.)
Prairie dock (Silphium terebinthinaceum), sometimes known as prairie rosinweed, is among the tallest plants on the tallgrass prairie. The U.S. Department of Agriculture lists Iowa as part of its native range. My understanding is that while prairie dock is common throughout Illinois, it doesn’t really belong in most parts of Iowa. However, I’ve seen it in several Des Moines area prairie plantings, where it blooms in August and September.
According to the Illinois Wildflowers website, prairie dock tolerates drought and “rocky or gravelly soil” well. Though “rather slow to develop,” this “long-lived plant” is “very reliable and nearly indestructible when mature.”