The Hexagonal Branching Pattern of Rhizomes of Alpinia speciosa L. (Zingiberaceae)

Abstract

Alpinia speciosa L. (Zingiberaceae) is a striking example of a plant in which an organized architectural structure fulfils a basic functional requirement - the economical exploration and exploitation of the substrate. This rhizomatous plant spreads laterally in a predictable manner by vegetative growth to form a clone of separated ramets. A morphological study establishes ‘rules of growth’ governing the success and failure of lateral branches (sympodial units), their lengths, and their relative angles. The basic branching pattern of this rhizome system approximates to that of a hexagonal grid - the most economical structural shape that uniformly ‘samples’ a plane surface. It is shown that the significant deviation of branching angle found in Alpinia from that required to develop an exact hexagonal network will virtually eliminate aerial shoot ‘clashes’ in which the placing of one aerial shoot coincides with that of another aerial shoot, whilst at the same time enhancing the benefits of the hexagonal system. The broader implications of the organised architecture of plants are emphasised.