From Bjornson 1945:  “Sisymbrium altissimum bears the common name, Jim Hill’s mustard, because the farthest west Jim Hill’s railroads were built the farthest west this weed grew. It always branches freely, and with plenty of moisture it can become a large plant, 5 feet tall. When mature, the stem breaks off at the ground line, and away the plant tumbles in the wind, scattering its many seeds as it goes.”