PRICKLY LETTUCE, Lactuca serriola L. 1, lower portion of plant; 2, upper part of plant with flowers; 3, seed; 4, distribution. Annual or winter annual, reproducing by seed. Taproot large. Stem erect, 2 to 6 feet (0.6 to 1.8 m) tall, stiff, leafy, hollow, prickly on the lower part and containing milky juice. Leaves large, coarse; lower leaves more or less lobed, upper ones small, linear; all with prickles along margin and along center of lower surface of midrib. Flower heads about 3/16 inch (4.5 mm) across, in open terminal clusters, composed of yellow ray flowers only. Seed black, rough, slender-tipped with a tuft of white bristles at upper end. Found in roadsides, fence rows, and wasteland.

 TALL LETTUCE, Lactuca canadensis L. 5, distribution. Similar to the above. Biennial, reproducing by seed. Leaves basal the first year, covered with powdery bloom, usually lanceolate, entire or with wavy margins, edges, smooth, midrib without prickles but may have a few hairs.