Tall Blue Lettuce, Wild Blue Lettuce: Lactuca biennis (Synonym: Sonchus biennis)
Louisiana Lettuce, Prairie Lettuce, Western Lettuce: Lactuca ludoviciana
Least Lettuce, Willow Lettuce: Lactuca saligna
Prickly Lettuce: Lactuca serriola (Synonyms: Lactuca scariola, Lactuca scariola var. integrata, Lactuca scariola var. scariola)