prickly lettuce(n = noun.plant) horse thistle, lactuca scariola, lactuca serriola - European annual wild lettuce having prickly stems; a troublesome weed in parts of United States;
is a kind of compass flower, compass plant

bibb lettuce, boston lettuce, butterhead lettuce, common lettuce, cos lettuce, crisphead lettuce, frog's lettuce, garden lettuce, head lettuce, iceberg lettuce, indian lettuce, lamb's lettuce, leaf lettuce, lettuce, loose-leaf lettuce, malheur wire lettuce, miner's lettuce, prickly, prickly ash, prickly custard apple, prickly heat, prickly pear, prickly pear cactus, prickly pine, prickly poppy, prickly shield fern, romaine lettuce, sea lettuce, stem lettuce, water lettuce, white lettuce