Some evidence for the existence of turgor pressure gradients in the sieve tubes of willow

摘要

Sieve tube sap was collected either from the severed stylets ofTuberolachnus salignus(Gmelin) or via incisions made into the phloem of small willow trees or potted cuttings. Measurements of the osmotic potential (O.P.) of sap samples showed a gradient to exist in the presumed direction of assimilate transport, ie from apex to base of the stem.