COMPARATIVE ANATOMY OF THE SECONDARY PHLOEM OF 10 SPECIES OF ROSACEAE

The anatomy of the secondary phloem of species belonging to four gener a in Rosaceae is described. The three genera of the Maloideae studied are more or less similar in their phloem anatomy; tangential bands of fibre-sclereids alternate with bands of sieve elements, companion cell s and parenchyma cells; superficially, the nonconducting and conductin g phloem are not distinct from one another, sieve plates are compound and there are conspicuous sieve areas on lateral walls; rays are unise riate and multiseriate, and homocellular. In the five species of Prunu s (Prunoideae) studied, there are no fibre-sclereids in the conducting phloem, end walls bearing simple sieve plates am oblique to nearly ho rizontal; and rays are uniseriate and multiseriate, homocellular.