What a thousand acres of Silphiums looked like when they tickled the bellies of the buffalo is a question never again to be answered, and perhaps not even asked.
A Sand County Almanac
Silphium are among the most interesting of the prairie forbs. They stand out, not only because of their enormous size, but because they all have interesting attributes.
Compass Plant (Silphium laciniatum) is usually the first of the Silphium to bloom
Like many sunflowers, the blossoms of Compass Plant turn toward the sun, from east to west. The 3-4” golden blossoms bloom alternately along the top half of the 3-9’ tall stems from early July through mid-to late August. The most striking feature of the plant, however, is its magnificent, oversize oak leaf-shaped leaves. They orient themselves in a north-south position, thus providing an accurate compass for native tribes and early settlers.
The next to bloom is Rosin Weed (Silphium integrifolium).
In the prairie, Rosin Weed grows 2-4’ tall; in my garden, it is over my head. (If you want a shorter plant, cut the stems back hard at the end of May.) Clusters of large, canary yellow daisies bloom at the top of the stems in July and August. The rough sandpapery, stalkless leaves are arranged in pairs along the length of the stiff stems. It’s called Rosin Weed because it produces resin along the stems and on the flower stalks that Indian and pioneer children used to chew like gum.
My favorite Silphium is Prairie Dock (Silphium terebinthinaceum). The enormous, rough, spade-shaped basal leaves are a dramatic presence in the prairie and make a striking focal point in the prairie garden from early spring through late fall and into the winter, as the leaves turn to a gorgeous red-mahogany. Hold your hands on both sides of the leaf–it will feel cold no matter how hot the day. At the beginning of July smooth leafless stalks rise up to 10’ or more; a cluster of yellow daisies begins to bloom at the top of each stalk the 3rd or 4th week in July.
The last to begin to bloom and my least favorite Silphium is Cup Plant–not because it is unattractive, but because it is so aggressive. I’ve never planted it–it just appeared spontaneously. And it keeps on appearing spontaneously–everywhere. It is a wetland plant, but it grows anywhere in the sun–at least it does in my yard. Clusters of large 2-4” lemon yellow daisy flowers bloom in the upper part of 3-8’ tall stems from mid-July through August.
Cup Plant at the corner of my garage
Like all the Silphium, there is a charming story to tell about it. Its huge triangular opposite leaves encircle the thick square stem to form a cup that holds rainwater. These little reservoirs provide water for birds, butterflies, dragonflies, and other insects.
Reservoir of rain water in its cup.
A Sea of Gold along my west side sidewalk.
This is mostly False Sunflower and Rosin Weed in bloom now.