The development of the primary and secondary phloem of peach and the secondarc phloem of cherry have been studied. In the peach the first protophloem sieve tube was found in the fifth of sixth leaf primordium. The first sieve tube develops in the ceneter of the abaxial side of the median leaf trace. Subsequent ones develop laterlly and adaxially to the first. As seen in transverse section of a young leaf trace, the procambium is a layer of polygonal cells between the primary xylem and primary phloem which usually divide more nearly in a periclinal than an anticlinal direction.
