This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Annual or winter annual. Propagates by seeds.
Time of bloom: June to August.
Seed-time: July to September.
Range: Newfoundland to Alaska, southward to North Carolina and Tennessee.
Habitat: In fields and along streams.
The foliage and, particularly, the seeds of this weed are very bitter, and when milch cattle eat it the dairy products are much damaged; also its juices are said to be so irritating to mucous surfaces as to bring about serious bowel disorders in stock. Its Greek name means "to draw blisters."
Stem eight inches to two feet tall, slender, and branching. Leaves lance-shaped to linear, entire or sparingly toothed, the lower ones tapering to a short petiole, the upper ones sessile; the whole plant minutely roughened with fine, forking hairs. Flowers about a quarter-inch broad, bright yellow; racemes slender, the siliques four-sided, narrow, smooth, a half-inch to an inch long, held erect on divergent pedicels, making a noticeable elbow between the pod and its stem. Seeds small, reddish yellow, varying in shape from being crowded in the pods but approaching a flattened oval; too often an impurity among clover seeds. (Fig. 138.)
Means of control the same as for Field Peppergrass.
Fig. 138. -Worm-seed Mustard (Erysimum cheiranthoides). X 1/4.