Time of bloom: June to September.
Seed-time: August to November.
Range: Maine and Ontario to South Carolina, Tennessee, and Texas.
A most troublesome weed where sheep are kept, for the long points of the calyx-lobes harden into hooked spines which catch in the fleeces to the detriment of the latter and which also help to distribute the seed. In this way many of the mountain pastures of the Pacific Coast have been so overrun with this weed as to crowd out all other growth. The taste is biting and persistently bitter, and no animal will eat the herb.
Fig. 241.- Blue Curls (Trichostema dicho-tomum). X 1/3.
The plant is used in medicine as a cough remedy and more than a quarter-million pounds of the dried herb are annually imported from Europe. The parts used are the leaves and the flowering tops, collected just before the buds open and quickly dried in the shade. The price is two or three cents a pound.
Stem one to two feet high, stout, erect, square, white-woolly, branching and bushy. Leaves opposite, broadly oval or rounded, with scalloped edges, wrinkled and rough-hairy above, white-woolly below, with large veins and short, stout petioles. Flowers nearly white, in dense axillary whorls, the upper lip of the small, tubular corolla notched, the lower one three-lobed and spreading; stamens included; calyx white-woolly, with ten awl-like, recurved teeth, the alternate ones shorter. Nutlets ovoid and smooth. (Fig. 242.)
Frequent and close cutting before seed development; or, if the colonies are not too large, removal by hoe-cutting. If the ground is fit for cultivated crops, the necessary tillage promptly destroys the weed.