This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Annual. Propagates by seeds. Time of bloom: July to September. Seed-time: August to October. Range: Tropical America, northward to Ontario and westward to
Pacific Coast. Habitat: Old pastures, neglected yards, roadsides, and waste places.
Most common in the South.
A strong-scented, unpleasant weed, rejected by all grazing animals, even goats. Stem two to four feet tall, erect, much branched, and very leafy. Leaves oblong to lance-shaped, one to three inches long, smooth, wavy-toothed or nearly entire, especially the upper ones, which are pointed at both ends and sessile or with very short petioles.
Flowers in dense terminal and axillary spikes, intermixed with small leaves; calyx green, its five lobes completely enclosing the small, black, flattened seed. (Fig. 66.)
Occupying the same range is a closely related plant, commonly called Worm-seed (C. am-brosioides, var. anthelminticum, Gray), differing chiefly in being perennial in latitudes where the ground does not freeze in winter; also, it is a larger, more strongly-scented plant, with more coarsely toothed leaves, two to five inches long and its flowering spikes often lacking the small, entire, sessile leaves that are intermingled with the flowers of Mexican Tea. Both plants are used in medicine as anthelmintics, and the seeds, from which the essential oil is usually distilled, are salable in the drug market for six to eight cents a pound. (Fig. 67.)
Close cutting or hand-pulling while in early bloom.
Fig. 66. - Mexican Tea (Cheno-podium ambrosioides). X 1/3.
Fig. 67. - Wormseed (Cheno podium ambro-sioides var. anthelminticum). X 1/3.