Angelica arguta is a large plant, up to six feet tall, found in shady, wooded locations at low to medium elevations. Stems and leaves are generally hairless. Leaves are pinnately divided up to three times into toothed, non-overlapping, bright green leaflets, which have a pinnate vein pattern. The overall length of a leaf can be up to 3 feet. Leaf stalks clasp the stem, and are inflated at the base.
The inflorescence is a compound umbel with between 20 and 60 rays, each bearing up to several dozen small white flowers. There are no bracts at either the base of the umbel or the individual clusters. Flower petals are hairless, unlike those of the similar
angelica breweri. Pedicels have varying lengths, in the range 1 to 4 inches, and they are webbed at the base.