15种松属植物茎次生韧皮部的解剖学研究

在光镜下观察了松属(Pinus L.)14种、1变种茎次生韧皮部结构,并对亚属间及一些种间差异进行了比较,主要结果为:(1)各种茎次生韧皮部结构基本一致。次生韧皮部由轴向和径向两个系统构成。轴向系统的主要成分为筛胞、韧皮薄壁组织细胞、含晶细胞和径向片;径向系统由单列和纺锤形两类射线组成。与具功能韧皮部相比,不具功能韧皮部的组成分子在形态、结构及排列上均发生显著变化。(2)次生韧皮部分层现象,射线扩张现象,树脂道密度,含晶细胞频率,韧皮薄壁组织细胞后合物含量,射线高度,以及筛胞长度、径向宽度和弦向宽度,筛域直径,直立射线细胞高度和径向宽度等许多方面存在一定的种间差异,但无明显的规律。(3)两亚属在晶体形状和长度、树脂道上皮细胞数(具功能或刚失去功能的韧皮部)等方面有较稳定的差异,可作为属内分类的进一步证据。

STUDY ON THE SECONDARY PHLOEM ANATOMY OF THE STEM OF 15 SPECIES IN PINUS

This paper deals with the structure of secondary phloem of stems in 14 species and 1 variety of Pinus ,and comparison of two subgenus(haploxylon,Diploxylon)and the different species. The main results are as follows; (1)The structure of secondary phloem is composed of an axial system and a radial system. The main constituents of the axial system are sieve cells, phloem parenchyma cells, crystalliferous cells and radial plates. The radial system is made up of uniseriate rays and fusiform rays containing horizontal resin canals. Compared with functioning phloem,the constituents of nonfunctioning phloem change greatly in form, structure and arrangement. (2)Some variations within various species have been shown in stratification of secondary phloem, phloem ray dilatation, resin canal density, crystalliferous cell frequency,quantity of ergastic substances in phloem parenchyma cell,phloem ray height, sieve cell length, radial and tangential width, sieve area diagram, height and radial width of upright ray cell, respectively. But no obvious regulation is found. (3) The differences are rather steady between two subgenus in shape and length of crystal, and number of epithelial cells around a resin canal in functioning phloem or phloem just losing its function,which can be served as the further evidence for separation of subgenus.