水松的次生韧皮部解剖及其系统位置的讨论

ANATOMY OF SECONDARY PHLOEM OF GLYPTOS-TROBUS IN RELATION TO ITS SYSTEMATIC POSITION

在光学显微镜和扫描电子显微镜下观察,水松茎次生韧皮部的主要特征为:韧皮部由轴向系统和径向系统组成。轴向系统由筛胞、韧皮薄壁组织细胞、蛋白细胞和韧皮纤维组成,径向系统由韧皮射线组成。在横切面上,轴向系统的各组成分子以单层切向带交替有规律的排列,其排列顺序为:筛胞韧皮薄壁组织细胞-韧皮纤维-筛胞。筛胞的径向壁上嵌埋有草酸钙结晶,韧皮纤维仅一种类型,韧皮射线同型、单列。根据水松茎次生韧皮部的解剖研究,并与杉科其它各属的有关资料进行比较,我们认为:水松属与水杉属和落羽杉属有较近的亲缘关系。

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.