Classification And Geographical Distribution Of Cassiope In China

Cassiope D.Don,a genus of the family Ericaceae,about 17 species in total on earth,is distributed in the circumpolar north to the Himalayas.Southwest China is the modem distribution centre of the genus.11 native species of Cassiope were recorded in the Flora Reipublicae Popularis Sinica and in the Flora of China.It is necessary to identify the species,because the genus has considerable ecological and economic value.Although previous researches had solved a lot of problems concerning taxonomy,Researches on classification revision and system evolution of Cassiope require to be conducted.In this dissertation,studies on Cassiope(Eriaceae,Cassiopoideae)was reviewed.Methods of classical classification integrating the study on leaf epidemics morphology,along with wood and pollen,were used to revise and complete the former taxonomic system.This research is base on article collection,field observations and specimen from the herbarium.Leaf epidermises of 7 species of Cassiope were investigated under light microscope.And Pollen morphology of 6 species of Cassiope were scanned under electron microscope and compared from the leaf epidermis,pollen morphology,and geographical distribution.The main results and discussion are given as follows:1.Leaf epidermal characters of 7 species of Cassiope D.Don were observed under light microscope.Found that the epidermal cells were usually irregular,and straight anticlinal walls,wavy or light wave,the stomatas were anonomcytic,and long axis of the stomatal apparatus were nearly parallel to the long axis.As a whole,the morphologic characters of Leaf epidermises of Cassiope are stable.The morphologic characters of leaf epidermises is a difference between plane and convex and are interrelated with other morphologic characters for individual.2.Pollen grains of 6 species in the genus Cassiope D.Don.were observed by scanning electron microscope(SEM).A1 l of them were arranged in tetrahedral tetrad and the shape of tetrad was orbicular triangle and adjoin tightly.Pollen grain of Cassiope were spheroidal or subspheroidal with tricolporate,in which pollen morphological characteristics were overlapped each other.The difference of pollen exine sculpture between sections in the genus can provide palynological proof for further taxonomy.However,the identification of some certain species in Cassiope by morphological data of pollen should be analyzed carefully.3.Assessment of the significant characters: The size of leaf,bract,the shape and size of the calyx,the shape and size of corolla lobes,the indument of calyx and corolla are sometimes quite variable within a species and even within a single plant and have certain taxonomic significance.However,the abaxial plane or convex,channel on back or not,length of the channel and shape,the indument of leaf are of considerable taxonomic importance in distinguishing species.4.Cassiope pulvinalis are regarded as new synonyms of Cassiope myosuroides5.Stamens of Cassiope palpebrata are ten instead of eight.6.The characters features of species,ecological habit and the relation to close species were analyzed,recorded and described.The distribution of the Cassiope species is plotted.7.Cassiope wardii is distributed in Tibet instead of Yunnan province.