Systemaitc Studies On The Phleum And Related Genera

The Phleum Linn belongs to the Pooideae, about16species, distributes inwarm-temperate regions and cold-temperate regions of the Northern Hemisphere, andextends to South America,used to be excellent forage.There are4species inChina.The systematic position of Phleum has been disputed for a long time.In this paper, the leaf abaxial epidermis, caryopsis morphology, plus ITS andtrnL-F sequences were utilized to infer the relationship among Phleum and relatedgenera based with the classification of Poaceae in Flora of China and FloraReipublicae Popularis Sinicae to furnish evidence for the phylogenetic position ofPhleum and related genera.Micromorphological study on leaf nether epidermis of56species of Poaceae(representing35genera) shows that the epidermal structure include long cell, shortcell and papillae et al. The appearance and distribution of them is inconsistent. Wedivided the taxa into four types and four subtypes. Contrasted with the classificationsystem of Poaceae, type Ⅰ are equals with the subfam. Oryzoideae; type Ⅱ includesthe taxa of subfam Panicoideae; type Ⅲ equals to the subfam Chlorideae.; and TypeIV represents the subfam Pooideae. The results indicated that leaf morphology ofPhleum,Alopecurus,Beckmannia,Deyeuxia,Avena,Agrostis,Poa,Puccinellia,Festucawere highly consistent, which belong to the subfam Pooideae. It proved that Aveneaeand Poeae should be merged.Light anatomical microscopes are used to examine caryopsis features of39species (representing28genera) of Poaceae. Three caryopsis types and sevensubtypes can be recognized according to differences in ventral face and hilummorphology et al. Contrasted with the classification system of Poaceae, type Ⅰareequals with the subfam. Eragrostideae and Panicoideae; type Ⅱincludes the taxa ofsubfam Pooideae; type Ⅲequals to the subfam Oryzoideae,Stipoid subtype andArundineae subtype. The results indicated that caryopsis morphology of Deyeuxia,Avena, Beckmannia, Agrostis, Poa, Puccinellia,Festuca were highly consistent, whichbelong to the subfam Pooideae. Phleum was considered to belong to the subfam Pooideae,while the caryopsis morphology was Arundineae subtype.There is parallelevolution during the evolutionary process,so caryopsis morphology of Phleum wasnot as same as the related genera. The evolutionary trend was not so obvious.Therewere some fuzzy boundaries among these genera.The study on ITS sequence and trnL-F of33species of Poaceae (representing19genera) shows that Poaceae formed monophyletic group comprised of two largeclades. It indicades that the relation is very close among Phleum, Alopecurus,Beckmannia,Deyeuxia,Avena,Agrostis,Poa,Puccinellia,Festuca,Calamagrostis,Phalaris.Phleum was related to Alopecurus,Beckmannia,Poa,Puccinellia,Festuca.Molecularevidence support Phleum, Alopecurus, Beckmannia belong to Poeae,and Poeae andAveneae shoulded be merged into a broad Poeae.The analyses of the leaf abaxial epidermis, caryopsis morphology and molecularevidence indicade that Phleum belongs to Poeae,closed with Alopecurus, Beckmannia,Poa, Puccinellia and Festuca. Phleum, Alopecurus, Beckmannia belong to Poeae,andPoeae and Aveneae shoulded be merged into a broad Poeae.