鹅观草属五个类群的核型与进化

报道了鹅观草属５个类群的核型，即长芒鹅观草，核型２ｎ＝４ｘ＝２８＝２２ｍ＋６ｓｍ（２ＳＡＴ）；短颖鹅观草，核型２ｎ＝４ｘ＝２８＝２０ｍ（２ＳＡＴ）＋８ｓｍ（２ＳＡＴ）；短柄鹅观草，核型２ｎ＝４ｘ＝２８＝２２ｍ（２ＳＡＴ）＋６ｓｍ；纤毛鹅观草，核型２ｎ＝４ｘ＝２８＝２０ｍ＋８ｓｍ（４ＳＡＴ）；毛盘鹅观草，核型２ｎ＝４ｘ＝２８＝１８ｍ＋６ｓｍ（４ＳＡＴ）＋４ｓｔ。同时，通过核型重要性状的递变分析，揭示了鹅观草属５个类群的相对进化程度以及宏观分类中４个组的系统发育关系，表明鹅观草属的半颖组在系统发育中可能既派生了颖体短小的小颖组，又派生了颖体长大的大颖组和长颖组。

Karyotypes and evolution of five taxa of Roegneria C Koch

The karyotypes of 5 taxa of Roegneria C Koch are reported in this paper The karyotype formulae are as follows: R dolichathera Keng, 2n=4x=28=22m + 6sm (2SAT); R breviglumis Keng var breviglumis, 2n=4x=28=20m (2SAT) + 8sm (2SAT); R breviglumis Keng var brevipes (Keng) L B Cai, 2n=4x=28=22m (2SAT) + 6sm; R ciliaris (Trin ) Nevski, 2n=4x=28=20m + 8sm (4SAT); R barbicalla Ohwi, 2n=4x=28=18m + 6sm (4SAT) + 4st Furthermore, according to Stebbins′ theory of the karyotypic evolution, the significant characters, which are the ratio of the longest chromosome to the shortest, the arm ratio in mean, the index of the karyotypic asymmetry and the proportion of chromosomes with arm ratio >2, were analysed The advance indexes which can reflect the evolutional levels of the 5 taxa were summarized The phylogenetic relationships of the 4 sections in the macroscopic classification were enunciated The results of study show that R dolichathera Keng is the most primitive among the 5 taxa, R barbicalla Ohwi is the most evolutive in them, while R breviglumis Keng var breviglumis, R breviglumis Keng var brevipes (Keng) L B Cai and R ciliaris (Trin ) Nevski are intermediate; in the phylogenetic process, the Sect Goulardia (Husnot) L B Cai of Roegneria C Koch might produce the Sect Roegneria which has a short and small glume body, also the Sect Ciliaria (Nevski) H L Yang and the Sect Curvata (Nevski) H L Yang which have a long and large glume body