NUMERICAL MORPHOLOGICAL ANALYSIS OF LETTUCE CULTIVARS AND SPECIES (LACTUCA SECT LACTUCA, ASTERACEAE)

L. sativa L. cultivars were compared morphologically with accessions o f L. saligna L., L. serriola L., and L. virosa L. in order to define t he infra- and interspecific variation. Multivariate analysis (principa l component analysis) distinguished four groups corresponding with the four species. Infraspecific variation (e.g., colour, leaf shape) with in L. sativa is the largest, because breeding has caused a large varia tion in vegetative features; infraspecific variation within L. serriol a is also large. Three plants of one accession were placed between L. sativa and L. serriola because they showed morphological characteristi cs of both species. They are still classified as L. sativa. The morpho logical differences between L. sativa and L. serriola are too large to consider these two as one species. The descent of the cultivar groups and the four species is described.