铁筷子(毛茛科)营养器官的结构及其系统学意义

应用解剖学方法,对铁筷子(Helleborus thibetanusFranch.)(毛茛科)营养器官的结构进行了研究。结果表明,铁筷子根的初生结构观察到三原型、四原型和六原型。营养器官中的维管束在横切面上木质部中的导管分子不呈“V”字形排列;根状茎的次生结构由外向内为表皮、皮层和维管柱,髓射线发达。茎的初生结构中多个维管束排列成环状,维管束鞘分化不明显,节部为单隙三迹,叶迹分别来自于3条维管束或同一条维管束。叶为两面叶,表皮细胞不规则;气孔器只分布于下表皮,为毛茛科典型的无规则型气孔。从铁筷子营养器官的解剖学特点来看,与毛茛科其它植物基本相同,但在营养器官中维管束木质部不呈“V”字形、维管束鞘分化不明显、节部具单叶隙等特征上与其它毛茛科植物不同。

Vegetative Organ Structures and Their Phylogenic Significance of Helleborus thibetanus Franch. (Ranunculaceae)

The vegetative organ structures of Helleborus thibetanus Franch.were observed by anatomical method,which showed that the primary structure of H.thibetanus roots fell into the categories of triarch,tetrarch and hexarch.In the vegetative organs the vascular bundles showed the xylem whose vessels were arranged in V-shape on their cross-sections;the secondary structure of the rhizomes was composed of epidermis,cortex,vascular cylinder and well-developed pith ray from outer to inner.In the primary structure of the stem multiple vascular bundles were annularly arranged and the vascular bundle sheath were not clearly differentiated and the nodes were unilacunar and composed of tree leaf traces that were separately from three vascular bundles or from same individual vascular bundles.The leaves were dorsi-ventral leaves with irregularly shaped epidermal cells and there were stomata only on their underside,which were irregular stomata typical of Ranunculaceae.According to their anatomical features the vegetative organs of H.thibetanus were basically the same as those of other Ranunculaceae plants,but in them the vascular bundles did not appear arranged in a V-shape,the vascular bundle sheath did appeared clearly differentiated and the nodes differed from those in the vegetative organs of other Ranunculaceae plants in such characters as singular leaf gap.