Mexico. Locally very abundant, especially in the wheat-growing parts of the West. Habitat: Grain and alfalfa fields, waste places.
An immigrant from Europe, where it is said to have been formerly used as a forage plant, the specific name, Vaccaria, having been given in allusion to its value as cow fodder. But it is listed among the "Stock-Poisoning Plants of Montana," in the bulletin of that name published by the United States Department of Agriculture, and its seeds, like those of Corn Cockle, contain a poisonous property that makes flour unwholesome and dangerous to use when by accident they are ground with wheat. Grain contaminated with these seeds is sharply "cut" in the market. (Fig. 102.)
Stem one to three feet tall, erect, slender, smooth, glaucous, round, and swollen at the joints, many-branched. Leaves long ovate, pointed, smooth and glaucous, opposite and clasping the stem, the pairs sometimes united at base. Flowers in loose corymbose clusters, on rather long, wiry pedicels; calyx a swelling, five-ribbed vase in two shades of green, the ribs darker and so prominent as to be angled wings; the five petals pink, veined with deeper pink, notched at the outer edge; stamens ten; styles two. Capsule ovoid, four-toothed, imperfectly two- to four-celled, containing twenty to thirty hard, nearly globular, black seeds, about a tenth of an inch in diameter. These seeds retain their vitality for several years when buried in the soil.
Fig. 102. - Cow Cockle (Saponaria Vaccaria). X 1/4.
Sow clean seed. A Montana miller stated that the quantity of Cow Cockle seed cleansed yearly from the wheat brought to his mill, and supposed to be already clean, was about a ton. Seed should be made as clean to sow in one's fields as to be eaten in bread. Raking the grain fields with a weeding harrow when the crop is but a few inches high will kill very many of the Cockle seedlings; those not killed by the harrow should be hand-pulled at the time of their earliest bloom, when they show very conspicuously among the grain. The process is a paying one, even though the weeds are so many as to make the task somewhat strenuous, for the food and moisture used in their development is stolen from the rightful crop, which is the poorer for it. Stubbles where the weed has matured seed should be burned over and the ground used for a cultivated crop before being again seeded to grain.