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Development of Vein Pattern in Leaves of Ostrya virginiana (Betulaceae)
Daniel H. Franck
Vol. 140, No. 1 (Mar., 1979), pp. 77-83
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/2473967
Page Count: 7
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Ontogeny of leaf primordia of Ostrya virginiana was studied to determine the histogenetic events which lead to the formation of the regular craspedodromous pattern, a venation type suggested to be phylogenetically advanced in angiosperms. A lamina is initiated by a marginal meristem and later expands by plate (intercalary) growth. From 14 to 16 secondary veins are formed in abaxial ridges of the lamina and develop in acropetal sequence. The procambium of each secondary vein differentiates progressively from midrib to margin. During its development, the leaf folds in a plicate manner. Each fold has a greater number of slightly larger cells on the adaxial side than on the abaxial surface. Tertiary veins arise simultaneously throughout the leaf when cells of the middle layer in the folded intercostal panels differentiate. Higher order veins develop sequentially, primarily from the middle layer of the lamina. Comparative analysis suggests that a precise control of lamina development yields a more regular vein pattern in the mature leaf.
Botanical Gazette © 1979 The University of Chicago Press