Water containing cavities in vascular bundles are found in

In monocot stem like Zea mays, vascular bundles are conjoint, collateral and closed. In vascular bundles, the lowermost protoxylem vessels and xylem parenchyma cells dissolve forming a water containing schizolysigenous cavity called protoxylem cavity or lacuna or lysigenous cavity. Protoxylem cavity and protophloem may be absent in the smaller vascular bundles in maize.