Vascular Anatomy of the Subterranean Organ of Ophioglossum vulgatum L.

Abstract

The vascular anatomy of subterranean rhizome and root of Ophioglossum vulgatum was studied. The vascular cylinder of the rhizome which had developed adventitiously is ectophloic siphonostele with endarch primary xylem maturation. In the basal part of the rhizome ectophloic siphonostele reveals a complete cylinder of vascular tissue, whereas an ectophloic siphonostele with overlapping gaps occurs in the upper part of the rhizome. Each meristele is arranged as collateral bundle. The bulk of primary xylary elements in the vascular bundles is radially aligned. The roots are monarch with exarch xylem maturation and the monarch vascular pattern reveals opposite arrangement of xylem and phloem. The relation between stelar and total root diameter shows a low correlation. No signs of secondary thickening are found either in the rhizomes or the monarch roots. The comparison of anatomical features of vascular system of the rhizome and root with other ferns shows significant differences.