Taxonomic Study Of Carex Sect.Paniceae(Cyperaceae),a Group Disjuncted Between E.Asia And N.America

Carex(Cyperaceae),with nearly 2000 species,is one of the worldwide largest genera of angiosperm.Carex sect.Paniceae,containing 20 species,mainly distributes in East Asia to North America,which is a medium sized section in Carex.Based on literature survey,specimen examination,field work and specimen collection,morphological and molecular evidences,the classification of Carex sect.Paniceae could provide a more comprehensive basis for the classification of species.The main study are as follows.Morphological and micromorphological characters of the perigynia of 10 species from East Asia and 5 species from North America were observed and measured.The shape of the perigynia are generally ovoid,inflated-trigonous,glabrous,thinly veined,with the apex contracted into a medium long or long beak,and orifice truncated,or2-lobed.The morphology of perigynia,shape of beak and length of beak had taxonomic and systematic significance,which could identify allies of East Asia.The species from East Asia differs from those from North America by the length and shape of beaks.Morphological and micromorphological characters of the achenes of 10 species from East Asia and 5 species from North America were observed and measured.The achenes shape from East Asia is generally obovoid,rarely elliptic obovate,trigonous.The epidermal cells are 4?8 gonal,with straight anticlinal walls,flat silica platform,solitary central silica body but non satellite silica bodies.The epidermal cells of the species from North America are 5?7 gonal,with straight or emarginate anticlinal walls.The stability of achene micromrophology exists different populations of same species,but it is quite different among allies.The characters of leaf anatomy 10 species from East Asia and 5 species from North America were observed and measured.The outline of leaf is lightly V-shape or flat shape,with air cavities and bulliform cells.Mesophyll cells under the epidermis have different degrees of differentiation,which showed the structure of leaf anatomy were closed.The structure of leaf anatomy showed difference among allies which could be used to distinguish them.The mesophyll cells under epidermis of the species from East Asia were usually divided into 1 or 2 layers,with well-developed bulliform cells.While those from North America were evenly divided into one layer and bulliform cells were undeveloped,which has certain systematic significance.Based on the phylogenetic analysis of nr DNA and cp DNA of 10 species from East Asia and species from North America and some other related groups was conducted.The phylogenetic trees constructed by nr DNA(ITS,ETS)and cp DNA(trn L-F,mat K)phylogeny trees are roughly consistent with those of nr DNA and cp DNA.The traditional morphological definition of sect.Paniceae is not a monophyletic group.The species from East Asia were monophyletic,but it is difficult to distinguish between North America group and its relative sections.Four major clades were detected with in East Asia sect.Paniceae clade,C.egena and C.papulosa clade,C.arisanensis,C.parciflora,C.vaniotii,C.macroglossa and C.zhejiangensis clade,C.laxa clade,C.egena,C.filipes and its relative taxa clade.But C.egena and C.filipes can not be distinguished.PCA analysis were performed on 26 population of 178 individuals,which were identified as 9 species from East Asia.The main distinguishable characters are height of culm,length of sheath,length of terminal spike and width of leaf.And C.egena,C.macroglossa,C.vaniotii and C.arakiana could be distinguished from each another,C.filipes and C.arisanensis in Zhejiang could be easily distinguished,whereas C.rouyana from Japan and C.zhejiangensis cannot.