Systematic Research Of Homegrown Rhynchospermum Group Of Lageniferinae (Asteraceae)

Nesom G L(1994) did his research about Subtribal classification of the Astereae(Asteraceae) and set up the subtrib Lageniferinae,which was divided into two groups: Lagenifera group and Rhynchospermum group.Now,homegrown Lagenifera group includes two genera:Lagenifera and Myriactis; homegrown Rhynchospermum group includes three genera: Rhynchospermum,Sheareria and Thespis。Mostly,we do our systematic research about the three interrogatory genera: Rhynchospermum,Sheareria and Thespis。Now this is the best classification system.However,scholars have different opinions on the three genera,it is one of the difficult problems in research of Asteraceae.So,the research is very important and senseful.Micromorphologic,SEM Photomicrograph,anatomy,cytology and molecular research is used to compare the three homegrown monotypic genus with other plants which belong to Astereae and Heliantheae in my study,and Conclude that:Sheareria should be moved from Heliantheae to Astereae,Rhynchospermum should move from subtrib Lageniferinae to subtrib Asterinae,further research about the subtribe that Thespis belongs to should do. 1 Micromorphologic researchMany kinds of micromorphologic characters from reproductive organ choosed in my research,4 important characters are posed to compare,such as anter trim tabs,anther collars,chapiters and ligules.Different subtrib has its special characters.But it is not enough to plot out the station of different genus from the subtrib,but from the micromorphologic research,proofs are found to oppugn the option that S.nana S.Moore should belongs to Subtrib Milleriinae(Heliantheae).2 SEM Photomicrograph researchSEM Photomicrographs of the adaxial surface of the ligules reveal that S.nana has linear epidermis cell with transverse stripes and a longitudinal median promontory-like protrusion, which are identical or similar to those of Aster ageratoides var.heterophyllus and Galatella dahurica of the tribe Astereae, and quite different from Eclipta prostrate and Wedelia chinensis(Trib.Heliantheae) which cells of the adaxial surface of the ligules are subround and papillose.Therefore, all the results strongly support the transfer of Sheareria from the tribe Heliantheae to the tribe Astereae.SEM Photomicrographs of the adaxial surface of the ligules of Rhynchospermum verticillatum Reinw.and Sheareria nana S. Moore and SEM Photomicrographs of the inboard surface of the petal of Thespis.divaricata DC.are identical or similar to those of Aster ageratoides var.heterophyllus and Galatella dahurica of the Tribe Astereae too.Which belong to Senecionoid type.3 Anatomy research5 species belong to 2 subtribs of Trib.Heliantheae,7 species belong to 5 subtribs of Trib.Astereae and 3 species of homegrown Rhynchospermum group are done ovary wall anatomy research.By comparison,in the interfascicular parts of nana and Rhynchospermum there are chractersare similar to Trib.Astereae not Trib.Heliantheae.Thespis.divaricata DC.is special for its developed Trichomes.4 Cytology researchS.nana is a diploid with a karyotypic formula 2n=2x=18m. The chromosome basic number of x=9 in S.nana is the same as that of the Chinese tribe Astereae,and different from that of the tribe Heliantheae.The longest chromosome/shortest chromosome is 2.07,with an average arm ratio of 1.15,karyotype type is 1A.5 Molecular research Myriactis is very similar to the type genus Lagenifera which belong to Lagenifera group of the subtrib. Lageniferinae,the relationship of them is very closed.However,for data from the system tree of ITS,conclusion drawed that Rhynchospermum,Sheareria and Thespis are separated from Myriactis,they have much closed relation to subtribes of the trib Astereae.So,from the research of molecular biology,the subtrib.Lageniferinae established by Nesom is not a monophyletic group.