The Vascular Pattern of a Rhizomatous Ginger (Alpinia speciosa L. Zingiberaceae). 2. The Rhizome

The vascular system in the underground rhizome of Alpinia speciosa L. (Zingiberaceae) is seen to be arranged in three distinct zones. (1) An inner system of ‘scattered’ vascular bundles which serial cinematography reveals to have an axial pattern conforming to the basic ‘palm’ configuration (a system of upwardly branching leaf traces with interconnections). (2) An intermediate zone comprising a thin perforated cylinder of anastomosing vascular strands having direct contact with both roots and inner system bundles. (3) An outer system of freely-anastomosing vascular bundles. Connexion of outer and inner system occurs in the form of extensive bridging from inner system leaf traces as they depart obliquely between the outer system network. The interrelation of the three systems, plus root and branch insertion, is illustrated by means of diagrammatic three-dimensional reconstructions. The intermediate zone is intimately associated with root insertions and with the inner system, and is shown to obliviate potential bottlenecks at the point of lateral branch insertion in this sympodial rhizome system. A comparison is made with other monocotyle-donous vascular systems.