Development of Mantle Leaves in Platycerium bifurcatum (Plypodiaceae) II. Vascular System

Platycerium bifurcatum(Polypodiaceae) 잎의 발생 II. 유관속계

Procambium developed in the histogenetical zone below the marginal meristem. The development of procambium is correlated with the developmental stage of the leaf. As long as the marginal cells are crescent-shaped, the first-order procambium develops. When the marginal cell becomes wedge-shaped, the higher order procambium appears. The reticulated venation is developed through forking and anastomosis. The meshes of the first order enlarge in the process of leaf growth and the meshes of the second and third order develop in the meshes of the first-order through the differentiation of the residual meristem. Therefore, the venation is hierachically arranged and is as recognizable from the thickening of the veins. The outermost vein is produced parallel to the leaf margin, in which the differences between the costal and intercostal parts of the marginal meristem are removed. The endodermis and pericycle differentiate from the same mother cell. The procambium and sclerenchyma originate from a common source during the first developmental stage. A small cellular cluster lies within the parenchyma at the upper and lower sides of the procambial trace and differentiates into sclerenchyma.