The stem is erect, stout, smooth, and unbranched except at the top. Upper leaves sessile and often unlobed, while lower leaves are considered short-petioled, and lobed. Leaves are alternate and light green; lower leaves can be 6 inches to 1 foot long, deeply cut, while upper leaves are slightly toothed. Perennial sowthistle can grow anywhere from 4 to 6 feet tall, reproducing by seeds and horizontal roots.  Rhizomes, horizontal underground stems, measure < 1 cm in diameter, usually 5-12 cm below the soil surface, and grow about 2 m or more in a single growing season.  One reason perennial sowthistle can survive cold temperatures is due to the fact that the roots can overwinter and survive temperatures to -16º C.