Vessels in Zingiberaceae: A light, scanning, and transmission microscope study

The Zingiberales is a tropical group of monocotyledons that includes eight recognized families. The order is considered by most taxonomists and phylogenists to be a monophyletic lineage of plants, but the phylogenetic relationships among genera are not clearly understood. The tracheary elements in the family Zingiberaceae were examined to characterize the diversity of structure and to better understand the phylogenetic relationships among related taxa. The distribution and specialization of tracheary elements in roots, stems and leaves of 54 species representing 25 genera were studied. Vessel elements were present in roots of all but one of the species examined, Plagiostachys philippinensis. Stems and leaves had only tracheids except for Aulotandra kamerunensis, which had vessels with simple perforation plates. The perforation plates and lateral walls of vessel elements were examined for the presence of pit membranes or their remnants with both scanning and transmission electron microscopy. The presence and condition of pit membranes depended upon the developmental stage, but the perforation plates of mature vessel elements lacked pit membranes entirely.