Time of bloom: June to October.
Seed-time: July to November.
Range: Ontario to Minnesota, southward to Kansas, Texas,
The deep, perennial rootstocks of this weed make it very difficult to suppress. Grazing animals usually avoid it, seeming to know the quality of its milky sap, which is acrid and strongly emetic.
Stem ten inches to two feet or more in height, bright green, erect, smooth or sometimes slightly hairy, often spotted, unbranched below the flower-cluster. Leaves narrowly oblong to lance-shape, obtuse at apex, smooth, rather thick, entire, one or two inches long, sessile or with very short petioles; those at the base of the umbelzwhorled, but those on the stem scattering. Rays of the umbel slender, usually five, each again twice or thrice fork-branched, the flowers at the base of the forks being several weeks earlier than the terminal ones; involucres on long peduncles, the five greenish yellow glands at the tip being subtended by large, white, rounded appendages simulating petals. Pod smooth, containing three bluntly ovoid, ash-colored seeds, about a twelfth of an inch long, smooth or faintly pitted.
Small areas or scattering plants are most quickly and economically ousted by grubbing up the rootstocks or by treating with a strong herbicide such as hot brine or caustic soda. Infestations too large to make such treatment practicable should be closely and repeatedly cut during the growing season, thus preventing any seed formation and starving the rootstocks, the process being kept up for at least two seasons. Or the land may be put under thorough cultivation, well fertilized, and then seeded to grass or clover.