Characteristics of Reference in Classifying Fossil Plants of Genera Metasequoia and Sequoia by Epidermal Features

Some morphological features of branches and leaves which fossil plant mostly preserved are similar to each other in genera of Taxodiaceae.Epidermal structures of leaves,the source of cellular information of fossil plants,provide the important evidence to separate the similar leaves of these genera in Taxodiaceous fossil plants.Metasequoia glyptostroboides is the only "Nearest Living Relatives (NLR)" of fossil Metasequoia and Sequoia sempervirens is the only NLRof fossil Sequoia.Epidermal structures of S.sempervirens were reported divergently.M.glyptostroboides and S.sempervirens have high variation within a single species.Characters obtained of epidermal structures are influenced by different methods and times of maceration and by amounts and degree of integrality of cuticles.