Stiff greenthread

Thelesperma filifolium (Hook.) A.Gray (Asteraceae), stiff greenthread or threadleaf greenthread, is a slender annual or short-lived perennial of the central and southwestern United States and adjacent northern Mexico, occurring from Nebraska, Colorado and Texas west to Arizona and south through Chihuahua and Coahuila. Plants form one to several glabrous, erect or ascending stems 20-70 cm tall arising from a slender taproot. The opposite leaves are pinnately or bipinnately dissected into very narrow, almost thread-like linear segments 1-3 cm long, giving the foliage an airy, feathery appearance. Solitary long-peduncled flower heads terminate the branches and bear eight bright yellow ray florets, each with a reddish-brown to maroon base, surrounding a darker disc of perfect tubular florets; the involucre is double, with reflexed outer phyllaries. Achenes are linear, slightly winged and lack a true pappus. It favors open prairies, dry rocky slopes, roadsides and disturbed calcareous soils.