Transport of 14C-labelled Assimilates and 32P-labelled Phosphate in Salix viminalis in Relation to Phyllotaxis and Leaf Age

Autoradiographic techniques have been used to investigate the transport of 14C-assimilates and 32P-phosphate in relation to phyllotaxis and age of leaves in Salix viminalis. The leaves borne on the young shoots of S. viminalis are arranged in five orthostichies. Three of these orthostichies share one main transport channel, a second channel being shared by the leaves on the remaining two orthostichies. Where two orthostichies are separated by an angular distance of 72°, transport may occur between leaves on these orthostichies. In addition to the phyllotaxis of the leafy shoot, it has been demonstrated that the age of the leaf is a factor which determines the distribution of materials between leaves.