Northern Prairie Wildlife Research Center
Found in most North Dakota counties lying north and east of the Missouri River, Philadelphia fleabane also occurs throughout much of temperate North America at elevations up to 6,500 ft.
This plant is a biennial or short-lived perennial from a simple or slightly-branched caudex (thickened stem base). Plants usually have fine hairs. Maximum height is almost 30 inches, but plants in our area are usually about half that height. The larger, basal leaves are usually toothed and about 4-6 inches long. Flower heads are numerous and about 3/4-inch wide. Each head consists of up to 150 tiny ray flowers surrounding numerous yellow disc flowers. Fruits are tiny achenes bearing 20-30 bristles.
Look for Philadelphia fleabane in early July in native pastures heavily or moderately grazed by cattle. More plants are found at the bases of slopes or other areas of increased soil moisture. Some Erigerons are purported to drive away fleas, relieve toothache, and cure various diseases, but I could find no references to any economic values for Philadelphia fleabane.
This plant is a member of the sunflower family (Asteraceae), an immense group containing over 15,000 species worldwide. The family contains edible species such as lettuce and salsify, ornamentals like chrysanthemums and zinnias, and noxious weeds like thistles and cockleburs.
The generic name Erigeron stems from the Greek eri, "early" and geron "old man," in reference to early-flowering plants with a hoary appearance. Philadelphicus means "Philadelphian" in botanical Latin. Philadelphia fleabane was described for science by the famous Swedish scientist Carl von Linne (Linnaeus). Botanists consider his Species Plantarum of 1753 to contain the first scientifically-acceptable descriptions of plants.