The morphological variation of some Crataegus populations (Rosaceae) in Greece and Yugoslavia

Morphological evidence of hybridization and introgression between Crataegus orien–talis Pallas ex M.–Bieb. and C. pycnoloba Boiss. & Heldr. in Boiss. was observed where the two species meet in the montane–subalpine zone of Mt Chelmos, Pelo–ponnisos. C. pycnoloba var. parnassica Diap. is a variant of C. orientalis. Greek and Yugoslavian material of C. monogyna Jacq., C. curvisepala Lindm. and their hybrid is compared with Danish material of the three taxa using the multivariate techniques of discriminant analysis and Wells' distance coefficient. The infraspecific variation of C. monogyna and the correct binary names for C. monogyna x orientalis ( C. x albanica Pojark. versus C. x polyacantha Jan) and C. curvisepala x monogyna (C. x kyrtostyla Fingerh.) are discussed.