金丝桃属植物叶中分泌结构的比较解剖学研究

Comparative anatomy of secretory structures of leaves in Hypericum L.

利用整体透明法、石蜡制片法和半薄切片法 ,对金丝桃属 9组 43种 1亚种 1变种的植物叶分泌结构的类型、形态、结构和分布进行了比较研究。结果表明 ,分泌结构是金丝桃属植物叶片普遍的结构特征 ,根据其分泌结构的特征 ,可划分为分泌细胞团、分泌囊 (道 )和韧皮部中分泌小管道等 3种分泌结构。其中 ,分泌细胞团按其在叶片的分布可分为叶缘型和散生型 ;分泌囊按其在叶横切面中的位置可分为栅栏组织型、海绵组织型、居中型 (位于栅栏组织型与海绵组织型之间 )和横跨叶肉组织型。根据分泌囊和分泌细胞团在该属植物叶中的分布可划分为 3种类型 :( 1 )只有分泌囊的类型 ;( 2 )只有分泌细胞团的类型 ;( 3)具分泌囊和分泌细胞团的类型。两种主要分泌结构的类型、分布密度、分布位置及其形态等方面在组间和种间均存在一定的差异 ,对金丝桃属属以下等级的区分具有一定意义。在此基础上 ,对该属分泌结构的形态演化以及金丝桃属各组间的亲缘关系进行了探讨。

The structure, type, morphology and location of secretory structures in leaves of 43 species, 1 subspecies and 1 variety of 9 sections in Hypericum L. were comparatively studied using tissue clearing, paraffin sectioning and thin sectioning. The results have shown that the presence of secretory structures is a common feature of leaves in this genus. According to their anatomical characteristics, the secretory structures can be divided into nodules, secretory cavities (canals) and tiny secretory tubes. In their distribution in leaves the nodules fall into two types: the leaf edge type and the scattered type. According to the location of cavities in the cross sections of leaves, the cavities can be divided into 4 types: the median type which is situated between the palisade tissue and spongy tissue, the palisade tissue type, the spongy tissue type and the across mesophyll type. Based on the location of cavities and nodules in leaves, the species in Hypericum can be divided into 3 groups: group Ⅰ, in which only cavities are present; group Ⅱ, in which only nodules are present; group Ⅲ, in which both cavities and nodules are present. The type, location, distribution density and morphology of secretory structures are of some taxonomic value at the level of species and of section in Hypericum L. From these observations, the evolutionary trends concerning the morphology and anatomy of secretory structures and the affinity among sections in the genus Hypericum are discussed.