This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds. Time of bloom: July to November. Seed-time: August to December. Range: Newfoundland to Manitoba, southward to Virginia, Ohio, and Illinois. Habitat: Moist fields and meadows, banks of streams, swamps.
Stem three to seven feet tall, stout, grooved, erect, reddish purple, bristly with short, stiff hairs, branching near the top. Leaves three to six inches long and an inch or more wide, oblong to lance-shaped, long-pointed, rough above, bristly on midrib below, toothed along the sides, clasping the stem with an auriculate base. Heads in loosely branched panicles, on rather short pedicels, each about an inch broad, with light yellow disk and many pale purple or lilac rays; bracts of the involucre usually in two rows, linear, smooth, green, spreading. Achenes hairy, the long, tufted pappus nearly white. This weed is in bloom so early that flowering stems are often cut with hay, and seeds ripen on the stalks. (Fig. 302.)
Deprive the plant of its loved moisture by better drainage. Prevent seed production and starve the perennial roots by frequent close cutting, and so fertilize, cultivate, and improve the ground that better plants will supersede the weed.