Observations on the Symmetry of the Shoot in Vicia faba and some Allied Species, and on the Transmission of some Morphogenetic Impulses

Abstract

Axillary buds occur in unsymmetrical arrangements so that any node must be either right- or left-handed. The two types occur in roughly equal numbers but are not randomly distributed. The condition of any node is determined partly by stimuli transmitted from the nodes below. The tissues of the stem can act as a filter, transmitting right- and left-handed stimuli with different degrees of efficiency. Although there are considerable interspecific differences in respect of these relationships, it is unlikely that the actual state of right- or left-handedness of a node is subject to any direct genetical control. In this respect the bud arrangements resemble phyllotactic spirals and differ from most other right- or left-handed structures occurring in plants.