三蕊草属Sinochasea Keng系统位置的研究

叶片表皮、叶片横切面、花粉和淀粉粒的微观特征，对青藏高原的特有类群三蕊草属ＳｉｎｏｃｈａｓｅａＫｅｎｇ的系统位置进行了探讨。结果表明，三蕊草Ｓ．ｔｒｉｇｙｎａＫｅｎｇ在上述微观性状上与毛蕊草Ｄｕｔｈｉｅａｂｒａｃｈｙｐｏｄｉａ（Ｐ．Ｃａｎｄａｒｇｙ）ＫｅｎｇｅｔＫｅｎｇｆ．差距最小，与冠毛草Ｓｔｅｐｈａｎａｃｈｎｅｐａｐｐｏｐｈｏｒｅａ（Ｈａｃｋ）Ｋｅｎｇ差距次之，与宝兴野青茅Ｄｅｙｅｕｘｉａｍｏｕｐｉｎｅｎｓｉｓ（Ｆｒａｎｃｈ．）Ｐｉｌｇｅｒ和拂子茅Ｃｈｌａｍａｇｒｏｓｔｉｓｅｐｉｇｅｉｏｓ（Ｌ．）Ｒｏｔｈ差距最大；三蕊草属的系统位置应处于毛蕊草所隶的燕麦族Ａｖｅｎｅａｅ中；在系统演化上，燕麦族是最原始的类群，它可能直接或间接地派生了针茅族Ｓｔｉｐｅａｅ和剪股颖族Ａｇｒｏｓｔｉｄｅａｅ。

STUDIES ON THE SYSTEMATIC POSITION OF THE GENUS SINOCHASEA

Based on the microscopic characters of epidermis of leaf blade, transverse section of leaf blade, pollen and starch grain, the systematic position of the genus Sinochasea which is an endemic genus on the Qing-Zang Plateau has been studied in the present paper. According to the information of related taxa of this genus furnished by professor Yi-li Keng, the control experiments of Duthiea brachypodia (P. Candargy) Keng et Keng f. of Aveneae, Stephanachne paposhorea (Hack. ) Keng of Stipeae, Dewuxia moupinensis (Franch. ) Pilger and Calamagrostis epigeios (L. ) Roth of Agrostideae, which were chosen as examined species representing these tribes in this paper have been made. The results show that the difference between the S.trigyna Keng and the D. brachypodia (P. Candargy) Keng et Keng f. in the above-mentioned microscopic characters is the smallest, the difference between the S. trigyna Keng and the S. pappophorea (Hack. ) Keng is secondary, and the difference between the S. trigyna Keng and the D. moupinensis (Franch.) Pilger or the C. epigeios (L. ) Roth is the biggest among these species; in systematic position, the genus Sinochasea should be in the tribe Aveneae the D. brachypodia (P. Candargy) keng et Keng f. belongs to, but not in the tribe Stipeae or Agrostideae; the tribe Aveneae is more primitive than the tribe Stipeae or Agrostideae inphylogenetic development, and the latter two t.ribes maybe derive from the tribe Aveneae directly or indirectly.