Thelesperma filifolium, commonly known as stiff greenthread, or plains greenthread, is a species of flowering plant in the aster family, Asteraceae. It is often found growing in shallow soils. It prefers disturbed sites in dry, sandy or gravelly soil with a neutral to basic pH. Stiff greenthread adapts to various soil conditions, including loam, clay, caliche, and roadsides. It blooms between March and June and often into the fall.