Comparative studies on secondary phloem of the species of trees and shrubs in Rosaceae

摘要

The comparative studies of the structure of secondary phloem in 10 species of 6 genera of Rosaceae were studied. The results of this observation indicated that the phloem structure in the same genus studied has many characteristics in common and that there are differences among the genera in type of sieve elements and crystal- contained cells and distribution of crystal- contained cells and parenchyma cells. Rays are uniseriate and multiseriate, and homocellular in all the species.