Croton Codiaeum variegatum (L.) Blume cultivars characterized by leaf phenotypic parameters

Croton Codiaeum variegatum (L.) Blume is a popular ornamental foliage plant that displays an anomalous range of variations in its leaf size, shape and color pattern. By fixing such leaf variations, more than 300 cultivars have been produced in the world. Until now, however, only a limited number of studies have been made to describe the leaf phenotypic diversity. Here we investigated the diversity of leaf phenotype in croton cultivars with a numerical taxonomic approach. One-way analysis of variance confirmed significant phenotypic variations in the croton cultivars for 12 quantitative leaf parameters. Among the numerical parameter tested, the leaf index that is the ratio of leaf length to leaf width showed the highest variability. High coefficient of variation values were observed in petiole length, leaf area and leaf down quarter width. In contrast with leaf morphology, the composition of leaf pigments that contribute to leaf coloration did not show diversity. Based on the analyses of the leaf parameters, we clustered the croton cultivars into four major groups. The results of this study provide a numerical basis for classification of croton cultivars. A possible involvement of transposon is discussed in terms of somatic mutation that results in the leaf phenotypic diversity.

► The first study of phenotypic description for the croton C. variegatum cultivars.
► Numerical taxonomic approaches verified unusual variations in the croton leaves.
► We recommend the leaf parameters for the classification of croton cultivars.
► Phenotypic diversity is discussed in terms of involvement of transposons.