Tumbling Mustard was introduced from Europe about 1887, and is an abundant weed in the grain fields of the west owing to its copious seed production and its efficient manner of spreading the seeds. When ripe the plant breaks off and is driven by the wind, and the seeds, of which it is reported that there may be as many as 1,500,-000 on a single plant, are spread broadcast.

The whole plant is dangerous, owing to its pungent oils. According to Pammel deep ulcers may be produced by it. The vegetative part is not palatable, but the seeds often find their way into feeds in quantity.

Tumbling Mustard is a branching plant, two to four feet high. The root leaves form a rosette, but later shrivel and disappear. The stem leaves are very varied and finely dissected. The flowers are pale yellow, about one-third of an inch across, and the slender pods are two to four inches long. They are borne as in other Mustards. Introduced from Europe, the plant has spread over the continent and is a very troublesome weed in the north west.

The seeds are either olive brown or greenish yellow, slightly roughened, oblong, angular, and about one-twenty-fifth of an inch long. The radicle shows up prominently through the thin seed coat, the grooves on each side being darkened. The palisade cells of this seed, like those of Wild Mustard, form a cherry red compound with chloral hydrate and hydrochloric acid.

Fig. 23.   Seeds of Tumbling Mustard

Fig. 23. - Seeds of Tumbling Mustard - Sisymbrium altissimum.

Five times natural size.