Two Evolutionary Lines of Taxodiaceae
杉科的两条演化路线

According to the karyotypic data the present author proposes two evolutio- nary lines, A and L (Fig. 1), in Taxodiaceae (Exclud. Sciadopitys). The former is characteri- zed by a relatively rapid increase of the mean arm ratio but a relatively slow rise of the ratio of the longest chromosome to the shortest one and it is composed of Cryptomeria, Glyptostrobus, Taxodium and Taiwania, which advance from primitive to progressive in the order. The latter is characterized by, on the contrary, a relatively slow increase of mean arm ratio and a relative- ly rapid rise of the ratio of chromosome size and it comprises Metasequoia, Sequoiadendron, Sequoia and Cunninghamia (probably Athrotaxis also), which advance in the order. The infer- ence is supported by the data from morphology, anatomy, embryology and so on.Key words Taxodiaceae; Karyotype; Evolutionary line