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.