Time of bloom: August to October.
Seed-time: September to November.
Range: Ontario, New York, and Massachusetts, southward to Florida and Alabama.
The large, tuberous roots of this weed are extremely bitter and once had the reputation of curing rattlesnake bites, whence its specific and common names; stem and leaves partake of the same quality, and, even when good forage is very scarce, grazing cattle will leave it unmolested to bloom and mature seed.
Stem two to four feet tall, erect, smooth, often purplish, not glaucous, branched above, and usually somewhat spreading. Leaves rather thick and firm, the lower ones often six or eight inches long and most variable in shape; pinnatifid or palmately lobed or halberd-form or heart-shaped, usually with wavy edges or coarsely and very irregularly toothed, the petioles winged; upper leaves long-ovate to lance-shaped, often entire. Panicles rather large, loose, fork-branched, upcurved, the heads pendulous, chiefly in terminal clusters but a few in the upper axils; florets eight to twelve, pale purple or cream-colored; involucre funnel-shaped, the bracts often purplish, usually somewhat bristly, spreading abruptly above the middle. Achenes yellowish brown, with straw-colored pappus.