=Description.=—American wormseed is an annual plant of the goosefoot family (Chenopodiaceæ), attaining a height of from 2 to 3 feet. The stem is grooved, usually much branched and leafy, the leaves oblong or oblong lance-shaped, somewhat acute at the apex, the lower ones 1 to 3 inches long and wavy-toothed, the numerous upper leaves much smaller and usually entire. From July to September the flowers are produced, followed throughout the autumn by the fruits, both of which are green and borne in crowded leafy spikes. The whole plant has a powerful, disagreeable odor, due to the essential oil which it contains. =Part used.=—The entire leafy part of the plant is sometimes employed for the distillation of the oil, although the fruit alone is listed in the Pharmacopœia of the United States. The fruit is distilled for the oil, which it contains in large quantities. The fruits are in the form of small grains, about the size of a pin head, globular but slightly flattened, greenish, and inclosing the small shining black seeds. They have the same powerful odor as the plant, which does not diminish when the fruit is dried, and the taste is bitter and pungent. American wormseed is an anthelmintic, that is, it has the property of expelling worms. The fruits of _Chenopodium anthelminticum_, another species of wormseed, are collected with those of the species just described. This plant is very similar to the American wormseed, the fruits being alike, and the only differences being that in _Chenopodium anthelminticum_ the stem is slightly taller, from 2½ to 3½ feet high, the leaves are more coarsely toothed, the flowers are borne in more elongated, usually leafless spikes, the odor is more pronounced and disagreeable, and the range and distribution of the plant are more limited. Wormseed is cultivated to a considerable extent in parts of Maryland, where the distillation of the plant for the oil is carried on. =Price.=—In ordinary seasons the price paid for chenopodium or wormseed ranges from 6 to 8 cents per pound. The oil distilled from wormseed is at present selling at $1.50 per pound. BLACK MUSTARD. _Brassica nigra_ (L.) Koch. (_Sinapis nigra_ L.) =Other common names.=—Brown mustard, red mustard. (Fig. 30.) [Illustration: FIG. 30.—Black mustard (_Brassica nigra_ (L.) Koch).] =Range and habitat.=—Black mustard, introduced from Europe, is a troublesome weed in many parts of the United States. It is common in almost every State in the Union along roadsides, in cultivated ground, and in waste places, being especially troublesome in grain fields and pastures. Both black and white mustards are cultivated in California. This plant is a great pest in southern California, covering thousands of acres and forming dense, impenetrable thickets over 6 feet in height, in which birds have their nesting places, and, by eating and excreting the seeds, help to spread this pernicious weed.