Studies in Crataegus (Rosaceae: Maloideae). IX. Short-shoot leaf heteroblasty in Crataegus crus-galli sensu lato

Abstract

In the taxa that constitute C. crus-galli L. s.l. short-shoot leaves vary progressively from node to node in both size and shape. The pattern of this variation may differ not only between taxa but also within taxa, among local stands. Failure to recognize such variation may confound taxonomic studies based on leaf shape, judging from the results of parallel canonical variates analyses differing in whether or not sampling was stratified by leaf position. With the incorporation of such stratification into the sampling design, leaf descriptors provide a valuable source of data for studies of group differentiation in Crataegus taxa.