Abstract
The sugar content of the sieve tube exudate of 16 tree species of 11 families has been analyzed. Only non-reducing oligosaccharides of the raffinose family have been found. Sucrose is the major transport sugar, but in some species most (Fraxinus americana) of part (Ulmus americana, Tilia americana) o( the sieve tube sugars are in the form of higher oligosaccharides, raffinose and stachyose.