The Prickly Lettuce Lactuca serriola differs e.g. in following attributes from the similar Great Lettuce Lactuca virosa: It's typically 1.20 meter high and its base rosette usually has withered at flower time, while the Great Lettuce is up to 2 meters high and its base rosette is usually still available at flower time. The leaves of the Prickly Lettuce are often very pinnate and standing almost vertically, while those of the Great Lettuce are rarely pinnate and standing more or less horizontally. The seed of the Prickly Lettuce is narrower than those of the Great Lettuce, and carries bristles at the tip towards the pappus, which is rarely the case in the Great Lettuce.