THE ANATOMY OF SECONDARY PHLOEM IN SCIADOPITYS VERTICILLATA (THNUB.) SIEB. ET ZUCC.

The anatomical characters of the secondary phloem of stem in Sciadopitys verticillata(Thunb.)Sieb.et Zucc.has been observed by means of both light and scanning electron microscopy. The main results are as follows:1. The axial system is composed of sieve cells, phloem parenchyma cells, albuminous cells and phloem fibers. Thc phloem rays are homogeneous, uniseriate, rarely partly biseriate.2. Many crystals of calcium oxalate are embedded in the radial walls of sieve cells.3. The thick-wall fibers form tangential bands, arranged 1—6 cells wide in radial row. Number of the tangential layers of sieve cells and phloem parenchyma cells between two fiber bands are irregular.4. No sclereids are found in the secondary phloem of main trunk.The systematic position of the genus Sciadopitys is discussed and the present study supports the view that Sciadopitys should be seperated from Taxodiaceae and independented a monotypic family, Sciadopityaceae.