This is a western plant that ranges from Alberta and British Columbia south to Nebraska and New Mexico at elevations below 10,500 ft. Leafystem fleabane is perennial from an underground woody structure called a caudex. Plants are up to two feet tall and covered with fine, spreading hairs. Basal leaves are up to five inches long and an inch wide. Up to 20 flower heads about an inch wide form atop the stems and on the axils of upper leaves.
Fruits are achenes as in sunflower and dandelion.
Look for leafystem fleabane in August in meadows or around the bases of hills. I have no information on the effects of grazing on this species, but cattle seem to avoid eating the more common fleabanes. 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 leafystem fleabane. The family contains edible species such as lettuce and salsify, ornamentals like chrysanthemums and zinnias, and noxious weeds like thistles and cockleburs. The specific epithet subtrinervis probably refers to nerves on the achenes that usually number less than three.