Introduced. Annual. Propagates by seeds. Time of bloom: May to July. Seed-time: June to August. Range: New Jersey southward to North Carolina; locally in a few places in interior states. Habitat: Clover fields.
This pest, like the preceding species, was brought to this country with the seeds of its host plant. The parasite is larger than the plant on which it feeds, and its presence in any abundance means ruin to the crop.
Stem brownish yellow, rather stout, softly downy, six to eighteen inches in height, without branches; the scales near the base are numerous and overlapping, oblong-ovate in shape; those above are smaller, more distant, and acute. Flower-spike three to six inches long, rather loose, each blossom subtended by one or two lance-shaped bracts nearly as long as itself; calyx cleft to the base above and below, the divisions two-parted, with long, awl-like points; corolla about a half-inch in length, with pale brownish yellow tube and lips purple-tinged or lilac, the upper one incurved and notched, the lower with three spreading, rounded lobes. Capsule about a quarter-inch long, crammed with abundant dust-like seeds, which, if allowed to ripen, are sown far and wide by the winds and which, in spite of their small size, have long vitality when in the soil. (Fig. 270.)
Permit no seed to form. Stalks, with the host plants, should be pulled as fast as they begin to bloom, and be piled with straw or other litter, soaked with oil, and burned. Under no circumstances should clover seed or hay from infested fields be offered in market; such material should be used up on the ground. The crop is best used by turning under for green manure, before the parasite matures seed, and clover should be left out of rotation on that ground for several years.
Fig. 270. - Clover Broom -rape (Orobanche minor). X 1/3.