Department of Applied Plant Science and Oriental Bio-herb Research Institute, Kangwon National University, Chuncheon, 200-701, Korea.
J Plant Res. 2014 May;127(3):373-88. doi: 10.1007/s10265-014-0625-3. Epub 2014 Feb 5.
The comparative study on leaf anatomy and stomata structures of six genera of Taxaceae s. l. was conducted. Leaf anatomical structures were very comparable to each other in tissue shape and their arrangements. Taxus, Austrotaxus, and Pseudotaxus have no foliar resin canal, whereas Amentotaxus, Cephalotaxus, and Torreya have a single resin canal located below the vascular bundle. Among them, Torreya was unique with thick-walled, almost round sclerenchymatous epidermal cells. In addition, Amentotaxus and Torreya were comprised of some fiber cells around the vascular bundle. Also, Amentotaxus resembled Cephalotaxus harringtonia and its var. nana because they have discontinuous fibrous hypodermis. However, C. fortunei lacked the same kind of cells. Stomata were arranged in two stomatal bands separated by a mid-vein. The most unique stomatal structure was of Taxus with papillose accessory cells forming stomatal apparatus and of Torreya with deeply seated stomata covered with a special filament structure. Some morphological and molecular studies have already been discussed for the alternative classification of taxad genera into different minor families. The present study is also similar to these hypotheses because each genus has their own individuality in anatomical structure and stomata morphology. In conclusion, these differences in leaf and stomata morphology neither strongly support the two tribes in Taxaceae nor fairly recognize the monogeneric family, Cephalotaxaceae. Rather, it might support an alternative classification of taxad genera in different minor families or a single family Taxaceae including Cephalotaxus. In this study, we would prefer the latter one because there is no clear reason to separate Cephalotaxus from the rest genera of Taxaceae. Therefore, Taxaceae should be redefined with broad circumscriptions including Cephalotaxus.
本研究对 Taxaceae 属下 6 个属的叶解剖结构和气孔形态进行了比较。在组织形态和排列上，叶解剖结构非常相似。Taxus、Austrotaxus 和 Pseudotaxus 没有叶树脂道，而 Amentotaxus、Cephalotaxus 和 Torreya 则具有单个位于维管束下方的树脂道。其中，Torreya 的特征为具有厚壁、近乎圆形的厚壁组织表皮细胞。此外，Amentotaxus 和 Torreya 含有一些围绕维管束的纤维细胞。此外，Amentotaxus 与 Cephalotaxus harringtonia 及其变种 nana 相似，因为它们具有不连续的纤维下皮。然而，C. fortunei 缺乏相同的细胞。气孔排列在两条位于中脉两侧的气孔带上。最独特的气孔结构是 Taxus，其具有乳头状附属细胞形成的气孔器，以及 Torreya，其具有深陷的气孔，被特殊的丝状结构覆盖。一些形态学和分子研究已经讨论了 Taxad 属的替代分类为不同的小科。本研究也与这些假说相似，因为每个属在解剖结构和气孔形态上都具有其独特性。总之，叶片和气孔形态的这些差异既不能强烈支持 Taxaceae 中的两个族，也不能公平地识别单属科 Cephalotaxaceae。相反，它可能支持 Taxad 属在不同小科或包括 Cephalotaxus 的单科 Taxaceae 中的替代分类。在本研究中，我们更倾向于后者，因为没有明确的理由将 Cephalotaxus 与 Taxaceae 的其他属分开。因此，Taxaceae 的定义应该扩大，包括 Cephalotaxus。
