中文摘要：

里白科（Gleicheniaceae）是古老的真蕨类植物,最早的化石记录可追溯到石炭纪。现存类群的属级分类和系统演化关系一直存在很大的分歧,为了进一步探讨该类群的起源演化,文中运用最大简约法和贝叶斯演绎方法对18种代表现存里白科植物全部6属（包括新测的12种）的叶绿体3个编码基因序列（atpB,rbcL和rps4）进行分析,探讨其主要分类群（属级）的系统演化关系。结果显示,里白科植物为一个单系群,由3个分支构成：里白属（Diplopterygium Nakai）和Gleichenia japonica构成一个分支;芒萁属（Dicranopteris Bernh.）和Gleichenella pec-tinata构成另一个分支;假芒萁属（Sticherus C.Presl）与单种属Stromatopteris Mettenius及Gleichenia dicarpa构成第三个分支。用宽松分子钟方法推测里白科主要类群的起源时间为：现代里白科植物起源于早白垩世（111—140Ma）,其主要分支类群随后发生多样性分化,里白属和芒萁属的快速辐射演化均发生在古近纪（40—64Ma,36—50Ma）。起源时间的估算结果暗示化石种三叠里白Diplopterygium triassica不应归入现代里白属,其归属需要重新考虑。

英文摘要：

Gleicheniaceae belong to an ancient lineage of leptosporangiate ferns that first appeared in the Carboniferous.The relationships among extant genera of the family are controversial.We analyze the phylogenetic relationships among species representing all six extant genera of the family,based on chloroplast rbcL,atpB and rps4 genes.The MP and BI trees based on individual sequences and the combined data are largely congruent,indicating that Gleicheniaceae form a well-supported monophyletic group.However,the generic relationships established herein do not agree with the traditional classifications.Three clades within Gleicheniaceae can be recognized,with the first clade comprising species of Diplopterygium Nakai and one species of Gleichenia J.E.Smith （G.japonica）,the se-cond clade including species of Dicranopteris Bernh and Gleichenella pectinata （Wild.） Ching,and the third clade of species from Stromatopteris Mettenius,Sticherus C.Presl,and Gleichenia （excluding G.japonica）.Our results suggest that genus Gleichenia needs to be redefined.On the basis of the phylogenetic pattern and fossil record,we further estimate the divergence time for the major clades of the family using the relaxed clock method.Extant taxa of Gleicheniaceae appear to have diverged in Early Cretaceous （111—140 Ma）,the two major members,Dicranopteris and Diplopterygium,are estimated to have diverged in Paleogene （40—64 Ma,36—50 Ma）.This dating result indicates that the Triassic fossil species Diplopterygium triassica may have been misplaced in the extant genus and should be assigned to a different genus.