Organographic distribution and specialization of vessels in Dioscorea sp.

Abstract

SummaryThe investigations of organographic distribution and specialization of vessel elements were made in three species of Dioscorea (Dioscoreaceae). Vessel distributions were studied in roots, nodes, internodes, petioles and midribs of leaves of each species. The vessel elements are chiefly cylindrical, or drum‐like, or globose when very short, rarely, fork‐shaped, conical or fusiform in shape. Perforation plates are chiefly scalariform, but reticulate, foraminate and rarely simple ones occur. The vessel elements had predominently two perforations or rarely one in all the organs examined, except in the nodes where some vessel elements possessed more than two perforation plates. The pits are simple and oval, circular, or elongated, and arrangement was either opposite, alternate or at random. Vessels were with or without tails. End walls were tapering or blunt. The three species of Dioscorea investigated have mostly primitive vessels except for some in nodes.