Sowthistle is the name of a group of weeds that grow wild in Europe. Several species of sowthistles have been introduced into the United States, where they have become a nuisance in gardens and fields. The annual sowthistle grows 2 to 3 feet (61 to 91 centimeters) high and has a branching stem. It contains a milky juice, and its flower heads resemble those of dandelions. Another type of sowthistle is the perennial sowthistle. Sowthistles are among the most troublesome weeds.
