Time of bloom: June to July.
Seed-time: July to August.
Range: Nova Scotia to Ontario and Michigan, southward to New Jersey and Ohio. Habitat: Clover fields and meadows.
An immigrant from Europe, brought to this country in impure clover seed and increasing its range by the same agency. The fleshy roots, though much inferior to the true Madder, are sometimes used for the production of a red dye.
Stems numerous, tufted, three to ten inches long, some erect and some spreading on the ground, very slender, square, and rough-hairy on the angles. Leaves about a half-inch long, narrow, rough-edged, sharp-pointed, sessile, and whorled in fours, fives, or sixes. Flowers very small, in dense terminal clusters or heads, surrounded by an involucral whorl of spiny-pointed, leaf-like bracts; they are blue (sometimes pink), the corollas funnel-shaped, with four or five spreading lobes, and as many stamens as lobes, inserted on the tube, the anthers exserted; style two-parted at summit. Ovary below the flower, two-celled and two-seeded, forming twin carpels which are indehiscent and crowned by the persistent, rough-hairy, four- to six-lobed calyx. (Fig. 276.)
Clover fields and meadows infested with this weed should be mowed very early, before the formation of seed. Being annual, it can thus be driven out in a year or two, if seeds are not allowed to foul the ground.