A winter annual up to 18 inches in height. Seedlings form a rosette of deeply lobed leaves. Seeds and flowers grow on erect stems.
Seeds are very small, oblong, and reddish brown.
One of the first plants to appear in the spring, shepherdspurse can grow slowly in the rosette stage during the cooler months. Seed stalks appear when the temperatures warm. Because shepherdspurse is in the mustard family, it resists trifluralin and most of the herbicides registered for broccoli, cabbage, and cauliflower. The similar growth habit means that it germinates at the same time, has a similar growth rate and habit, and can compete directly with cole crops to reduce yields. One plant produces thousands of small seeds.