地枫皮营养器官解剖结构特征及其叶片结构的生态适应性

为了明确地枫皮的结构特征及其在石灰岩山顶和山腰疏林间两种环境下生长的叶片解剖结构的差异,本研究采用石蜡切片和半薄切片对地枫皮营养器官进行解剖观察并评价了叶片结构对不同生态环境的响应。结果表明:地枫皮根中次生维管组织发达,木射线和韧皮射线明显。老茎的次生构造中,皮层贮藏物质丰富,内有大的石细胞群,韧皮射线和木射线明显;而髓细胞内含有大量晶簇和少量单晶。在叶片横切面观上,叶为异面叶,表皮细胞一层,上表皮无气孔分布,主脉中薄壁细胞中分散有石细胞。叶片解剖结构显示,随海拔高度上升,地枫皮趋向于旱生植物的特点,其主要表现在叶片表皮细胞外壁角质层加厚,栅海比增加、海绵组织排列由紧密变疏松。另外,根皮、茎皮和叶肉中都分布有大量油细胞。

Anatomical Features of Vegetative Organs and Ecological Adaptability of Leaf Structure of Illicium difengpi

In order to study the structural characteristic of Illicium difengpi, and the difference of leaf anatomy between leaves from trees which grow in the limestone mountaintop and the open mountainside forest, the paraffin and half thin section technology were used to observe the vegetative organs of Illicium difengpi and the responses of leaf structure in different ecological environments were also evaluated. The results show that in roots, the secondary vascular tissue is well developed and the xylem ray and phloem ray are all obvious. In stem, the storage substance in secondary structure is abundant and has large stone cells group, and the xylem ray and phloem ray are apparent as well, while marrow cells containe a large number of druse and a few of single crystal. In the cross section, the leaf is typically bifacial, and epidermal cells are only in one layer and no stomata is in the upper epidermis. Moreover, there are sclereids scattered in parenchyma cells of main vein. The anatomical features of leaf show that the I. difengpi has the characters of typical xerophytic plants when it grows in naked limestone mountaintop. The cuticle of leaf epidermis cell wall is thicker and the ratio of palisade to spongy tissuesis increased, but the cells of spongy tissue become to be organized loosely rather than tightly. In addition, there are a large number of oil cells distributed in velamen, bark and mesophyll.