This is a rather pretty plant, a foot or more tall, with more or less hairy stems and leaves and pretty clusters of magenta flowers, each about a quarter of an inch across. It grows on the rim of the Grand Canyon.
There are many kinds of Erysimum, most abundant in Europe and Asia. They are usually biennial or perennial, more or less downy; mostly with yellow flowers; the pods long, narrow and squarish or flattish, rarely round, with numerous seeds, in one row. In Europe these plants often grow in the crannies of old walls, hence the common name.