Time of bloom: July to September.
Seed-time: Late August to November.
Its deep, running rootstocks make this weed much more pernicious than its annual relatives, for the ground cannot be rid of its presence until these are killed. Stem one to two feet tall, sparsely set with flat hairs, slightly angled, and at first upright but later diffusely branched and spreading on the ground. Leaves broadly lance-shaped to spatulate, usually obtuse, tapering to the petiole, entire or rarely wavy-edged. Flowers dull yellow with brownish centers, each about a half-inch broad, on peduncles about as long as themselves; calyx at first hairy but when inflated almost smooth, nearly ovoid in shape, not sunken around the stem, its ten ribs showing merely as lines on the surface. Berry reddish yellow, about a half-inch in diameter. (Fig. 258.)
Starve the rootstocks by persistently depriving them of leaf-growth, beginning with the first bloom; retarding new growth by the use of salt or a few drops of kerosene on the shorn surfaces. In cultivated crops tillage should be continued much later than is usual, for it is generally the late green foliage that assimilates the food which restocks the underground storehouses. Small areas may be killed outright by more liberal applications of kerosene, caustic soda or hot brine, making the ground barren for a season; or the root-stocks may be grubbed out.