Anatomy of Secondary Phloem of Glyptostrobus in Relation to Its Systematic Position
水松的次生韧皮部解剖及其系统位置的讨论

A anatomical characters of secondary phloem in Glyptostrobus pensilis (Staunt.)Koch were observed by means of both light and scanning electron microscopy(SEM). The secondary phloem is composed of axial and radial systems. In the axial systems, the phloem consists of sieve cells, phloem parenchyma cells, albuminous cell and phloem fibers. In the radial systems, it consists of phloem rays. The alternate arrangement of different cells in cross section results in tangential bands. The sequence of radial arrangement follows the pattern of sieve cells, phloem parenchyma cells, sieve cells and phloem fibers, sieve cells. Many crystals of calbium oxalate are embedded in the radial walls of seive cells. The phloem fibers are of only one type. The phloem rays are homogeneous, uniseriate. According to the anatomical characters of secondary phloem of Glyptostrobus pensilis (Staunt.)Koch and comparison with the other genera of Taxodiaceae, Glyptostrobus, Metasequoia and Taxodium have close relationships.