类叶升麻毛茛科次生木质部管状分子的研究

Tracheary Elements in Secondary Xylem of Actaea asiatica (Ranunculaceae)

利用扫描电子显微镜对毛茛科类叶升麻(Actaea asiatica Hara)根和根状茎次生木质部中的管状分子进行观察，发现其管状分子类型丰富，主要有：管胞、管胞状导管、纤维导管和典型的导管分子，其中管胞、管胞状导管和纤维导管为在该类群中首次报道；在导管分子中，存在着梯状穿孔板、网状穿孔板、混合型穿孔板和单穿孔板，其中网状穿孔板和混合型穿孔板为在该类群中的首次报道；对其导管分子上的侧壁穿孔板、多穿孔板和纹孔膜残余也进行了描述。根据类叶升麻次生木质部中多变的管状分子类型，认为以往积累的有关毛茛科植物管状分子类型及导管穿孔板类型是不全面的，因此以该性状为参考作出的有关某一个类群的原始性和进化性的推论也是不可靠的。同时探讨了不同类型管状分子在类叶升麻不同器官的分布与其生理功能和生态环境的关系，同时将该植物作为毛茛科的代表类群，与其它基部类群植物导管分子进行了比较。

The tracheary elements in secondary xylems of Actaea asiatica root and rhizomes were observered with a scanning electron microscope and found to contain abundant types, which mainly included tracheids, tracheid-like vessels, fibriform vessels,and typical vessels. Of these types, the tracheids, tracheidlike vessels,fibriform vessels were first found. Scalariform perforation plates,reticulate perforation plates, mixed perforation plates and simple perforation plates were observed in the typical vessels and the reticulate perforation plates ,mixed perforation plates were first founded-the lateral-wall perforation plates ,multiple end walls and pit membrane vestige were also observed in the tracheary elements. The diverse types of tracheary elements and perforation plates in secondary xylem of A. asiatica show that previous knowledge about the tracheary elements and perforation plates in secondary xylem of A. asiatica is not complete and thus any inferences about the aboriginality and evolution of a taxon made depending on these traits are not reliable. In addition,the paper discusses the distributions of different types of tracheary elements and the relations of their physiological functions with ecological environments,and compares the tracheids of other basal taxa using this plant as the representative of Ranunculaceae.