Of the14C labelled sugars (sucrose, glucose and fructose) and14C proline, the incorporation of label into different lipid types was least from proline while sucrose was the preferred precursor over glucose or fructose. High incorporation into phosphatidyl inositol with14C sucrose suggested that this phosphatide besides being a membrane component served possibly as the inositol storage component. High incorporation of label into phosphatidyl choline also suggested synthesis of new membranes during pollen tube growth.