Abstract: The sequences of the ITS regions and 5.8S coding region of nuclear ribosomal DNA from the genus Tetrathyrium and the related genera of Hamamelidaceae were determined and analysed. Based on the ITS sequences, the phylogeny of Hamamelidoideae was reconstructed, which was similar to Endress' system of Hamamelidaceae in 1989. It was shown that all the species of the subfamily Hamamelidoideae formed a monophyletic group in this study. However within both Hamamelidoideae and the tribe Hamamelideae, the polyphyly was indicated in the MPTs. The monophyly of the tribe Eustigmateae was strongly supported (in-cluding Eustigma, Fortunearia and Sinowilsonia ). The ITS data supported Endress' treatment of merging the tribe Distylieae and Fothergilleae too. It was suggested that the genus Hamamelis was closely related to Fothergilleae in this study. Tetrathyrium and Loropetalum {armed a monophyletic group.

Key words: Terathyium

摘要： 测定和分析了四药门花等13种金缕梅科(Hamamelidaceae)植物的核糖体DNA转录间隔区(ITS区)及5.8S编码区的序列。应用最大简约法构建的分子系统树表明：被分析的金缕梅亚科(Hamaelidoideae)植物形成一个单系类群，亚科内及其中的金缕梅族 (Hamamelideae)内部呈复系演化(polyphyletic)的特征；支持秀柱花族(Eustigmateae)(含秀柱花属Eustigma、牛鼻栓属Fortuneanria和白树属Sinowilsonia)成立以及将蚊母树族(Dis-tylieae)与弗特吉族(Fothergilleae)合并的观点,此结果与Endress(1989)系统接近;金缕梅族中金缕梅属(Hamamelis)与弗特吉族中的弗特吉属(Forthergilla)、银缕梅属 (Shaniodendron)水丝梨属(Sycopsis)系统发育关系密切;四药门花(Tetrathyrium)与继木属(Loropetalum)属于同一个单系类群，它们与Hamamelis的亲缘关系较远。

关键词: 四药门花属, 金缕梅亚科, 系统发育, ITS区, 核糖体DNA