Description of morphological characters of lettuce (Lactuca sativa L.) genetic resources. A review

Lettuce (Lactuca sativa) is the most important crop in the group of leafy vegetables. It is characterized by considerable morphological and genetic variation. The crop comprises seven main groups of cultivars (including oilseed lettuce) differing phenotypically; they are usually described as morphotypes. Lettuce breeding is primarily focused on various morphological features and resistance against diseases and pests. The accurate description of lettuce germplasm provides basic information useful for lettuce breeders. A list consisting of 55 descriptors has been constructed. These descriptors, along with descriptors of wild Lactuca species, provide an efficient analytical tool for studying the complex morphological variability of this genus and relationships among the species.