关键词: 红豆杉科, 次生韧皮部, 比较解剖, 系统演化

Abstract: 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).

Key words: Taxaceae, Secondary Phloem, Comparative anatomy, Phylogeny