The Leaf FTIR, Morphology And Anatomy Of Camellia Plants With Cork Wart And Their Taxonomic Significations

Camellia L.is the largest but relatively original genus in family Theaceae.The taxonomic treatments of the genus Camellia are still bitterly controversial in classifications of subgenera,sections or species. There are three recent taxonomic treatments of the genus Camellia frequently referred to in Camellia literatures:Sealy's treatment,Chang's treatment,Ming's treatment,but these treatments are still controversial. Therefore,there still are significant to further study the taxonomic problem of genus Camellia.The leaf FTIR,morphology,anatomy,and the development of cork wart of Camellia plants,including sect.Archecamellia Sealy,sect. Stereocarpus(Pierre)Sealy,sect.Furfuracea Chang and sect. Chrysanthae Chang,were investigated in this study.These investigations had clarified many Camellia taxonomic problems and contributed to understand the phylogenesis of genus Camellia.Based on our researches,we concluded as followings:(â…°)A simple definition of leaf shape had been proved to be a difficult exercise,due to the extreme diversity.The PCA were conducted using the transformed value of the measurements of area,perimeter, width,length,aspect ratio(width/length)and leaf formcoefficient obtained by scanning leaf shape.Large and broad leaf shapes were specific to sect.Chrysanthae.The leaves of sect.Stereocarpus were small.We found that the leaf shapes were different among sect.Archecamellia,sect.Stereocarpus,sect.Furfuracea,sect. Chrysanthae.These samples were obviously clustered into four groups and therefore supported Chang's treatment.(â…±)The epidermal characters were various among different taxa and constant within the same taxon,and therefore they were significant to the classifications of taxa below genus:section and species. Various epidermal cells were found in sect.Archecamellia(there were two different epidermal cells arranging alternately).There were crystals in epidermal cells of sect.Chrysanthae.Most of epidermal cells in sect.Furfuracea were polygonal.(â…²)Different leaf chemical compositions among Camellia species resulted in various peaks and wavenumbers in the FTIR spectrum. The comparisons of leaf FTIR indicated that most differences were specific to the carbohydrate fingerprinting region(wavenumbers 1500cm^-1-1000cm^-1).FTIR characters figured out the relationships among sect.Archecamellia,sect.Stereocarpus,sect.Furfuracea, sect.Chrysanthae.FTIR data supported Chang treated sect. Furfuracea,sect.Chrysanthae as natural taxa.It seems that sect. Archecamellia and sect.Stereocarpus should been merged,but this need further research.(â…³)Cork wart originated from D-type stoma which was large, infrequent and emerged on young leaf at early developmental stages.Typical stoma was small,frequent and emerged on young, unfolded leaf.The subsidial7 cells of D-type stoma divided and suberized gradually in the progress of maturing.Cork wart finally formed.Pressure experiment indicated that cork wart played a role of gas exchange.Cork wart is probably evolutionary character which contributes to gas exchange.However,it also increases water loss.Therefore,these plants usually distribute in areas of abundant rainfall while arid or semiarid environment is not suitable to them.Further researches about the physiological functions of the two types of stomata in young leaves of Camellia plants with cork wart will contribute to understand the evolution and distribution of genus Camellia.To sum up,Chang's taxonomic treatment about the classifications of sect.Archecamellia,sect.Stereocarpus,sect.Furfuracea and sect. Chrysanthae was supported by the data of leaf FTIR,morphology and anatomy.Additionally,this study laid a base for further researches on Camellia taxonomy.