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..
Erect, usually branching herbs, with alternate leaves, and (in our species) rather large discoid many-flowered heads of whitish flowers, corymbose-paniculate at the ends of the stem and branches. Involucre cylindric, swollen at the base, its principal bracts in 1 series, linear, with or without some much smaller outer ones. Receptacle concave, naked. Marginal flowers in 2-several series, pistillate, fertile, their corollas filiform, the limb 2-4-toothed. Central flowers perfect, fertile; corolla narrowly tubular, the limb 4-5-toothed, the style-branches elongated, truncate or obtuse at the summit. Anthers obtuse and entire at the base. Achenes linear-oblong, angled or striate. Pappus of copious capillary soft smooth white bristles. [Ancient name of some groundsel.]
About 12 species, natives of America and Australasia. The following typical one is the only species known to occur in North America.
Senecio hieracifolius L. Sp. Pl. 866. 1753. E. prealta Raf. Fl. Ludov. 65. 1817. Erechtites hieracifolia Raf. DC. Prodr. 6: 294. 1837.
Annual, glabrous, or somewhat hirsute; stem striate, succulent, usually branched, 1°-8° high. Leaves thin, lanceolate or ovate-lanceolate, dentate and often deeply incised, 2' - 8' long, the upper sessile or auriculate-clasping, mostly acuminate, the lower usually narrowed into petioles; heads 6"-10" long, about 3" in diameter, the involucre conspicuously swollen at the base before flowering, its bracts numerous, striate, green, with narrow scarious margins; pappus bright white.
In woodlands, thickets and waste places, very abundant after fires, Newfoundland to Florida, Ontario, Saskatchewan, Nebraska and Texas. Also in Mexico, the West Indies and South America. Pilewort. July-Sept.