Most of the species are annual herbs, a few are perennial, and a few are even woody.
Annual herbs in the genus are known as sow thistles (less commonly hare thistles or hare lettuces). The genus is named after the Ancient Greek for such plants. All are characterized by soft, somewhat irregularly lobed leaves that clasp the stem and, at least initially, form a basal rosette. The stem contains a milky latex. Flower heads are yellow and range in size from half to one inch in diameter; the florets are all of ray type.