凤尾蕨科的假脉及其相关构造之形态.doc

國立台灣大學生態學與演化生物學研究所碩、博士專題討論摘要 日期：2008年3月21 日題目：鳳尾蕨科的假脈及其相關構造之形態、結構及功能的探討講者：高資棟指導老師:黃玲瓏教授邱文良博士摘要：假脈是蕨類分類上一個常可被應用的特徵。綜觀過去的研究文獻，不同的作者對假脈的構造有不同的定義。且通常只適用於部分的類群。此外，就其結構、起源以及功能都有顯著的差異。因此重新定義以利於有效的區分不同類型的假脈有其必要性。初步就文獻資料與部分重新觀察的結果中，可將蕨類的假脈分為三個主要的類型。第一類型是由葉緣癒合而成，其在蕨類演化的過程中可能曾多次發生。觀音座蓮科、瓶爾小草科、骨碎補科、鐵角蕨科與金星蕨科的假脈屬於此類型。第二類型是葉脈退化所殘留的構造，可見於膜蕨科。第三類型的假脈是由位於葉面的矽細胞所構成，存在廣義的鳳尾蕨科中。本論文擬先針對第三類型的假脈進一步的研究。假脈是鳳尾蕨屬內相當重要的分類特徵。1978年Wagner對假脈與相關構造的解剖特徵進行較詳細的描述與討論，他並提出鳳尾蕨屬的假脈和鐵線蕨-碎米蕨類群 (Adiantoid- Cheilanthoid ferns) 以及書帶蕨類群 (Vittarioideae) 特稱為矽異形細胞 (Spicular cells 或 epidermal idioblast，即有針狀矽結晶的長形細胞) 的結構相似，目前這兩個類群亦均被歸併在廣義的鳳尾蕨科中。然而鐵線蕨屬的矽異形細胞分布在脈上，而書帶蕨類群的則分布在葉脈以外的表皮細胞上。這兩類型的矽異形細胞是否屬於同類型的構造一度有所爭論。此外，尚未有報告直接證實鳳尾蕨屬的假脈中含有矽，因此鐵線蕨屬、書帶蕨類群以及鳳尾蕨屬的假脈有待進一步確認其相關性。初步由微量元素分析結果，已確定鳳尾蕨屬的假脈上具有大量的矽，且亦確定了鐵線蕨屬及書帶蕨類群的矽異形細胞具有矽。鳳尾蕨科中尚有些零星的有些類群曾有假脈的報導，然而這些類群亦有所爭議。因此本研究進一步觀察這些尚欠缺資料或有疑問的類群，檢視在廣義的鳳尾蕨科中，尚有哪些類群具有類似假脈的構造。此外依據Schuettpelz等人在2007發表鳳尾蕨科的分類系統，從其五個大支 (Clade) 中選取了分別屬於22個屬的29個物種，利用簡易型的掃描式電子顯微鏡 (TM-1000) 檢視其葉表是否具有類似假脈的構造。比較各類群間假脈的外型、分布以及解剖構造的異同，並探究其是否符合現今演化樹之趨勢。葉表的矽細胞的功能在單子葉植物中已有相當的研究成果。然而過去對鳳尾蕨科由矽異形細胞形成之假脈的研究主要集中在分類及形態上的描述， 對其功能則鮮少有討論。因此，本研究擬就鳳尾蕨科中具有假脈類群的葉片的解剖構造、生活型與生育地以及其在演化樹上的位置對其功能提出合理的推論。參考文獻：Gracano, D.; Azevedo, A. A.; Pardo, J., 2001. Anatomia foliar das espcies de Pteridaceae do Parque Estadual do Rio Doce (PERD) - MG1. Revta brasil. Bot., So Paulo, 24: 333-347.Nayar, B.K. 1962. Studies in Pteridaceae V. Contributions to the morphology of some species of the maidenhair ferns. Botanical Journal of Linnean Society, 185:185-199.Ogura, Y. 1972. Comparative anatomy of vegetative organs of the pteridophytes. 2ed. Gebrder Bornt raeger, Berlin. Schuettpelz, E., 2007. A molecular phylogeny of the fern family Pteridaceae: Assessing overall relationships and the affinities of previously unsampled genera. Molecular Phylogenetics and Evolution, 44: 11721185.Wagner, Jr. W. H., 1978. Venuloid idioblast in Pteris and Their systematic implications. Acta Phytotax. Geobot., 29: 33-40.Williams, M. Sc., 1927. A critical examination of Vittarieae with a view to their systematic comparison. Trans. Roy. Soc. Edin., 9: 173-217.Topic:Morphology, Structure and Function of false veins in Pteridaceae s.l. Speaker:Kao, Tzu-TongAdviser:Dr. Kuo-Huang, Ling-Long Dr. Chiou, Wen-LiangAbstract:False vein is a useful character in fern classification. Varies of definitions of false veins used by different authors. When review all structure report as false vein, we found most of these definition can only apply to a part of taxa reported with false vein. On the other hand, the structure, origin and function of these false veins are significant different. Its necessary to define different type of false veins. By reviewing articles, we roughly divide false vein into three types. The first type is deriving from fusion of leaflets. This kind of structure evolves many times in the evolution history of ferns. Marattiaceae、Ophioglossaceae、Thepteriaceae、Davalliaceae and Aspleniaceae have this kind of false veins. The second type of false veins may come from reduction of true veins. This kind of false vein is found in Hymenophyllaceae. The third type false vein is composing of spicular cells (epidermal idioblasts containing silica crystals). This type of false vein is found in Pteridaceae s.l. The “False veins” are found in the genus of Pteris as an important character for species identifyication. 1978, Wanger suggest this structure may be the same to the “spicular cells” in Vittaridaceae and Adiantoid-Cheilanthoid ferns, but has not been confirm to have silica. Also, spicular cells in Vittaridaceae and genus Adianum may not be the same because their distribution was suggest by some authors. We analysis the trace elements in false veins and spicular cells in these taxa, and find all of these structures contain mass of silica.Some other genera of Pteridaceae also reported to have “spicular cells” or “false veins” but lacking further description or conflict in different papers. These taxa are discrete in different lineage of Pteridaceae. As a result, we sample 29 species belong to 22 genus. The sampling covers all five clades of Pteridaceae (sensu Schuettpelz, 2007). We use SEM to inspect the leaf surface of these species for false-vein-like structures. Later, we will compare the morphology, distribution and anatomical structure of these taxa and we will inspect if the result fit with recent phylogeny tree. After all, we would like to use the anatomical structure, habitat, life form and other evidence to suggest the possible function of false veins in Pteridaceae. Reference:Gracano, D.; Azevedo, A. A.; Pardo, J., 2001. Anatomia foliar das espcies de Pteridaceae do Parque Estadual do Rio Doce (PERD) - MG1. Revta brasil. Bot., So Paulo, 24: 333-347.Nayar, B.K. 1962. Studies in Pteridaceae V. Contributions to the morphology of some species of the maidenhair ferns. Botanical Journal of Linnean Society, 185:185-199.Ogura, Y. 1972. Comparative anatomy of vegetative organs of the pteridophytes. 2ed. Gebrder Bornt raeger, Berlin. Schuettpelz, E., 2007. A molecular phylogeny of the fern family Pteridaceae: Assessing overall relationships and the affinities of previously unsampled genera. Molecular Phylogenetics and Evolution, 44