【作者】 朱立涛；

【导师】 李法曾；

【作者基本信息】 山东师范大学 ， 植物学， 2007， 硕士

【摘要】 三芒草属Aristida L.属于禾本科,约300个种,广泛分布于温带和亚热带的干旱地区。中国产约10种。由于三芒草属独特的形态学特征和叶解剖学特征,三芒草属的系统学位置一直存在较大的争议。本文从叶表皮微形态、颖果形态特征、分子系统学等方面进行研究,试图为三芒草属的系统学地位提供新的证据。主要研究内容如下:叶表皮微形态方面,利用光学显微镜对三芒草属及芦竹亚科、画眉草亚科、早熟禾亚科、黍亚科和稻亚科的代表属进行观察研究。根据叶表皮微形态特征,将其分为2大类型,即类型Ⅰ、类型Ⅱ,其中类型Ⅰ又分为2个亚型a、b,类型Ⅱ又分为3个亚型,即c、d、e。结果表明,三芒草属除具备了长细胞和气孔器细胞的基本特征外,其硅质体为黍型,与黍亚科、稻亚科的硅质体属于同一类型,均为哑铃形,而芦竹亚科也有哑铃形的硅质体;三芒草属的其它特征如刺毛、微毛,乳突等与画眉草亚科、芦竹亚科、黍亚科都有共同之处。因此从叶表皮特征来看,三芒草属的系统学关系比较特殊,与这几个亚科之间有着紧密的联系,兼有这几个亚科的共同特征,认为无论将三芒草属放在芦竹亚科还是画眉草亚科,都不合适。颖果形态方面,利用解剖镜对三芒草属及芦竹亚科、画眉草亚科、黍亚科、早熟禾亚科和稻亚科的代表属植物进行观察研究,根据腹面特征和种脐形态将所观察的类群分为三种类型,五个亚型,即类型Ⅰ、类型Ⅱ、类型Ⅲ,其中类型Ⅰ分为2个亚型,类型Ⅲ分为3个亚型。结果表明三芒草属的大多特征与早熟禾亚科针茅族的针茅属、芨芨草属、落芒草属的颖果形态特征比较相似,而胚比数值和种脐形态也与芦竹亚科相近,说明三芒草属的系统学位置比较特殊,与其它亚科的代表属颖果形态不是截然分开的,成为类群间联系的纽带和演化中的过渡桥梁。分子系统学方面,采用核基因ITS序列和叶绿体trnL-F基因序列对三芒草属及近缘属进行分析。结果显示,ITS序列和trnL-F序列将三芒草属及近缘属植物明显地分为2大姊妹支Ⅰ和Ⅱ,支Ⅰ又分为4个姐妹分支A、B、C、D。其中分支A、B、C与传统分类上的画眉草亚科、黍亚科、芦竹亚科相一致,而三芒草属支,即D分支与A分子、B分子、C分子很明显的聚为4个姐妹支,研究结果表明三芒草属应该从芦竹亚科或画眉草亚科中分出来,成立三芒草亚科。从叶表皮微形态、颖果形态及结合分子系统学等证据,本文研究结果认为应将三芒草属升为亚科水平,成立三芒草亚科,与画眉草亚科、芦竹亚科及黍亚科的系统关系为姐妹群关系。更多还原

【Abstract】 The genus Aristida L. which belongs to the family Poaceae, about 300 species, widely distributed in tropical and warm-temperate regions of the world and ten species (six endemic) in China. This genus is found on poor dry soils in areas of low rainfall, but does not usually penetrate into true desert. Due to its unique morphology and leaf anatomy structure, the systematic status of Aristida has still a great mater of debate.In this thesis, the systematic status of the Aristida has been documented by means of leaf abaxial epidermis, caryopsis morphology, and molecular systematics, which provide new evidences for systematic position of Aristida. The results are summarized as follows:Leaf abaxial epidermis. Light microscopes are used to examine leaf epidermal features of 40 species of the genus Aristida and related genera of the family Poaceae. Based on the leaf epidermis features, two types and five subtypes can be recognized. The results show that the type of silica-bodies of the genus Aristida shares the same type with the subfamily Panicoideae and Oryzoideae besides the basic feature such as long cell, stomata, however the same type of silica-bodies also is in some genera of the subfamily Arundinoideae. Other features of Aristida, such as prickle-hairs, micro-hairs, papillae, are also found in other subfamily. Then the results show the systematic position of Aristida has its peculiar status, which has close relationships with other subfamilies, and it is not reasonable that be transferred it to subfamily Arundinoideae or Chloridoideae.Caryopsis morphology. Light anatomical microscopes are used to examine caryopsis features of 36 species of the genus Aristida and related genera of the family Poaceae. Three caryopsis types and five subtypes can be recognized according to differences in ventral face and hilum morphology, First is the groove ventral face, corresponding with a needle-shaped hilum, Second type is the concave ventral face, corresponding with a linera hilum, the third type is the flat ventral face, corresponding with a round, elliptic or oblong hilum,. The results indicate that the genus of Aristida share the same features with the genera of Stipa, Achnatherum, Oryzopsis of subfamily Pooideae, and close hilum proportion and hilum morphology with subfamily Arundinoideae. All of these show that Aristida has its peculiar status which has close relationship with other subfamilies, and become the ligament among the species.Molecular phylogeny. The systematic rank of Aristida is discussed and examined the phylogenetic relationships between this genus and related genera in the Poaceae using ITS and trnL-F DNA fragment. The results show that Poaceae formed monophyletic group comprised of two large clades. CladeⅠcontains 4 subclades labeled A, B, C, D. Of these, subclades A, B, C correspond with the subfamily Chloridoideae, Panicoideae, Arundinoideae. And cladeⅡcorresponds with subfamily Pooideae. However, the subclade D, that is Atistida clade, is the sister to these clades. The result indicate that it be proposed to remove this genus Aristida from the subfamily Arundinoideae or Chloridoideae, and its rank of Aristida should be promoted to the subfamily rank, that is Aristidoideae.In conclusion, Based on Leaf abaxial epidermis, Caryopsis morphology, Molecular phylogeny, the present study indicate that genus rank of Aristida should be promoted to the subfamily rank, that is Aristidoideae, which is sister to the subfamilies: Chloridoideae, Panicoideae, Arundinoideae更多还原