红豆杉科次生韧皮部的比较解剖

在光学显微镜及扫描电镜下，比较观察了红豆杉科Ｔａｘａｃｅａｅ５属即红豆杉属Ｔａｘｕｓ，白豆杉属Ｐｓｅｕｄｏｔａｘｕｓ、穗花杉属Ａｍｅｎｔｏｔａｘｕｓ，榧树属Ｔｏｒｒｅｙａ和澳洲红豆杉属８种植物茎次生韧皮部的结构。其主要结果为：红豆杉科植物茎次生皮部由轴向系统和径向系统两部分构成。轴向系统由筛胞，韧皮薄壁组织细胞，蛋白细胞及韧皮纤维组成；径向系统由韧皮射线构成，但是，在横切面上，各个组成分子的层次有

COMPARATIVE ANATOMY OF THE SECONDARY PHLOEM OF TAXACEAE

The family Taxaceae contains five genus, Taxus, Pseudotaxus, Amentotaxus, Torreya, Austrotaxus, except for Austrotaxus mastly endemic to China. The prensent paper deals with the comparative anatomy of secondary phloem of stems in 8 species of five genus and light microscope and scanning electron microscope. The main results are as follows: The secondary phloem of Taxaceae is composed of axial and radial systems. In the axial system the phloem consists of sieve cells, phloem parenchyma cells, albuminous cells and phloem fibers. In the radial systemit consists of phloem rays. In cross section the layer of consists elements are different. The forms, size, quantity, have or not of crystal and the forms of crystal of phloem fibers are different. This can be served as the characters for identification of genus and also provding the evideuce for the tribes in the family. Based on the fact that crystals are absenton the outer surface of phloem fibers in Austrotaxus and present on the fibers of other four genera. The forms, size and frequency of crystals on the wall surfaces of the phloem fibers in four genera of Taxaceae are different. It can be divided into four tribes: Taxeae (including Taxus and Pseudotaxus), Austrotaxeae ( Austrotaxus ),Amentotaxeae (Amentotaxs) and Torreyeae ( Torreya).