This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
White-woolly annual herbs, with alternate entire leaves, and small discoid clustered heads, usually subtended by leafy bracts. Bracts of the involucre few and scarious. Receptacle convex or elongated, chaffy, each chaffy scale subtending an achene. Outer flowers of the heads in several series, pistillate, fertile, their corollas filiform, minutly 2-4-dentate. Central flowers few, perfect, mainly sterile, their corollas tubular, 4-5-toothed. Anthers sagittate at the base, the auricles acuminate. Achenes compressed or terete. Pappus none. [Latin filum, a thread.]
About 12 species, natives of temperate or warm regions of both the New World and the Old. In addition to the following, 3 others occur in the western and southwestern United States. Type species: Filago pygmaea L.
338. 1841. Filago prolifera Britton, Mem. Torr. Club 5: 329. 1894.
Stem simple, or branched at the base, very leafy, 2'-6' high. Leaves spatulate, obtuse, sessile, ascending or appressed, 4"-8" long, 1"-21/2" wide; heads in a sessile leafy-bracted cluster, usually subtended by 1 or several slender, nearly leafless branches, each terminated by a similar cluster, or these again proliferous; heads oblong or fusiform; receptacle convex; chaff of the central sterile flowers woolly-tipped, that of the fertile flowers scarious, mostly glabrous.
In dry soil, Texas to western Kansas and South Dakota, west to Colorado and New Mexico. April-July.