11种裸子植物筛分子质体的超微结构及分类

透射电镜下观察了红豆杉科、三尖杉科和罗汉松科１１种裸子植物筛分子质体的超微结构，测量了筛分子质体的大小及其内含物的平均直径和数目．它们的筛分子质体均属Ｓ－型，同属植物所含淀粉粒的形态特征相同．红豆杉科内红豆杉属和穗花杉属的特征相近，白豆杉属和榧树属更为接近．三尖杉科（属）的篦子三尖杉筛分子质体的大小、所含淀粉粒的数目和其余植物差异明显，支持成立篦子三尖杉组．筛分子质体超微结构的观察结果还显示罗汉松科较三尖杉科、红豆杉科更为原始，竹柏组应保留在罗汉松科内．

The Sieve Element Plastid Ultrastructure of 11 Gymnosperm Species and Its Taxonomical Significance

species of Taxaceae, Cephalotaxaceae and Podocarpaceae have been investigated with the TEM for ultrastructural characters from their sieve elements, of which 10 species are studied for the first time. Quantitative data from sieve-element plastids(size, as well as average diameter and number of their contents)is also used to deduce the phylogenetic relationship. All of the species tested contain S-type plastids, and the starch grains are of the same shape within genus. In Taxaceae, the ultrastructure of Taxus are similar to that of Amentotaxus, while Pseudotaxus resemble Torreya. In Cephalotaxaceae, it is found that C. oliveri is quite different from the rest members within the same genus, Cephalotaxus, what supports to divide the genus into two sections, Sect. Pectinatae and Sect. Cephalotaxus. It is reasonable to include Sect. Nageia in Podocarpaceae.