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 and by rootstocks. Time of bloom: May to July. Seed-time: June to August.
Fig. 352. - Stinking Willie (Senecio Jacoboea).
Range: Newfoundland to Florida, westward to Ontario, Missouri, and Texas. Habitat: Moist fields and meadows, banks of streams, and swamps.
The slender, creeping rootstocks of this plant are strong-scented, whence its name of False Valerian. It is said to be unwholesome for cattle and horses, but not so much so as Senecio Jacobaea; sheep feed on it, however, without any apparent harm.
Stems two or three from the same root, very slender, grooved, marked with twisting brown streaks, one to three feet tall. When young the whole plant is webby-haired but soon becomes smooth. Root leaves appear in early April and look somewhat like those of the violet; heart-shaped, rather thick in texture, scallop-toothed, dark green above, purplish red beneath, with long, slim petioles. Stem leaves very different; the lower ones oblong, pinnatifid, with terminal segments large, and with short, margined petioles; those near the top more slender, sessile, and clasping. Flowers in open, flat clusters, the heads nearly an inch broad, with eight to twelve deep golden rays and brownish orange disks, both kinds of florets fertile. Achenes ribbed and smooth, with very copious, silky, white pappus, by which they are borne far on the winds.
Prevent spreading by seed production by cutting while in first bloom. In small areas, rootstocks may be hand-pulled or grubbed out; but drainage and cultivation of the ground are necessary in order to cleanse rankly infested fields and meadows of this weed.