A morphometric analysis of leaf development in Vitis riparia, and grape cultivars Concord and Vivant

This study investigates the initiation of leaf shape in three taxa of Vitis from a quantitative point of view. Leaf characters, such as angles between major veins, ratios of the length of leaf lobes, of leaf lobes and sinuses, and of petioles and leaf lobes, were measured on leaves of different sizes and compared against leaf blade length (an indirect measure of developmental time) to see if there were differences between them at different developmental stages, and between taxa. Two trends were observed. Characters dealing with angles between major leaf veins, and those dealing with the ratio of the distance to the first point of branching of the major leaf vein of a lobe and the length of that leaf lobe, showed relatively little change over leaf blade length compared to more variable characters such as those involving the leaf petiole, leaf sinuses, or leaf lobes. If we assume that leaves of different lengths represent leaves at different stages of development, we can say that the characters dealing with angles or venation do not change extensively over time. However, characters dealing with ratios of the distance to a leaf sinus and lobe length, ratios of the length of two leaf lobes, or those dealing with the ratio of the length of the petiole and lobe length showed a stronger indication of change over leaf blade length. The parameters of interest in most of these ratios (petiole length or sinus depth compared against the length of a leaf lobe) varied more at different leaf blade lengths. It was also possible to distinguish between taxa for characters dealing with leaf lobes, petioles, and sinuses. Key words: morphometry, leaves, Vitis, development, characters, shape.