台灣產冷水麻屬植物之分類研究

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2011

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本研究利用外部形態、地理分布、葉綠體trnL-F基因序列和核ITS基因序列等資料,對台灣產冷水麻屬植物進行分類研究。外部形態研究結果顯示托葉形態、葉緣形態、葉片氣孔與鐘乳體的分布、花被數目和形態為重要分類特徵,植株習性、毛被的有無、花序和瘦果微細形態亦可提供分類的參考;本研究結果將台灣產冷水麻屬植物處理為14個分類群,將Pilea peploides var. major併入P. peploides,且將P. sinofasciata併入P. matsudae,另將P. miyakei處理為疑問種,其餘皆支持第二版台灣植物誌的處理。 Weddell及陳家瑞曾以形態特徵為主要依據分別提出兩個不同的屬內分類系統,但Monro根據分子研究已證實這兩個以形態建構的屬下分類系統並無法反映本屬植物之親緣關係。本研究利用葉綠體trnL-F基因序列和核ITS基因序列建構親緣關係樹,檢視本屬各分類群之間的關係,並訂正陳家瑞建構的屬下分類系統。結果顯示P. japonica與長梗盤花麻歸在同一支序,分類地位必須重新檢討;過去所定義的四萼組為一旁系群(paraphyly),三萼組和冷水花組則為多系群(polyphyly)。本研究重新修訂四萼組的形態特徵及範圍,也提供其餘支序與形態特徵和地理區系的關聯,以利未來進一步的屬下分類訂正。
In this study, the genus Pilea in Taiwan was taxonomically revised based on morphological, geographical, and molecular phylogenetical studies. The results suggest that morphology of stipule and leaf margin, distribution of stoma and cystolith on leaf surface, tepal number and tepal morphology are the most important characters for classification of Taiwanese species. Plant habit, present of hair, inflorescence and achene morphology also provide useful information. As a result, 14 taxa of Pilea were recognized in Taiwan. Pilea peploides var. major was treated as the synonym of P. peploides; Pilea sinofasciata was treated as the synonym of P. matsudae, and P. miyakei was treated as an uncertain species. Except for the treatments above, others were agreed that of Flora of Taiwan 2nd ed. Within Pilea there have been two different subgeneric classifications, Weddell’s and Chen’s, both of them are based on morphological characters. The incongruence of morphology and phylogeny of the two subgeneric classifications was proved in Monro’s molecular study. To explore the phylogenetic relationship of the genus and to revise Chen’s subgeneric classification, cpDNA trnL-F region and nrDNA ITS were used to construct a phylogenetic tree. The genus Lecanthus and P. japonica form a monophyletic group, which suggests the taxonomic status of P. japonica should be further confirmed. The results suggest Chen's sect. Tetrameris forms a paraphyly, and both sect. Urticella and sect. Pilea are polyphyletic group. This study revised the sect. Tetrameris, but also provided the relationships of the other clades with morphology and geographic distribution It might enable the revision of the genus in the future.

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冷水麻屬, 蕁麻科, 分類, 屬下分類系統, 分子親緣, Pilea, Urticaceae, taxonomic, subgeneric classification, molecular phylogeny

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