水杉属和红杉属化石叶表皮鉴定参照系的特殊性

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

杉科植物的许多属种在小枝的形态和叶片排列上相似 ,而杉科植物的化石标本多保存为枝叶形式。表皮的特征作为压型化石枝叶标本细胞信息的重要来源 ,甚至是惟一来源 ,一直作为杉科植物化石分类鉴定的主要依据。水杉和北美红杉分别是水杉属和红杉属植物化石的惟一现存最近亲缘种 ,以往关于北美红杉的气孔分布和排列等方面的报道存在分歧。根据作者的研究 ,北美红杉的表皮特征变异幅度非常广 ,水杉的气孔分布也与以往报道有差异。利用表皮的特征鉴定杉科植物化石时 :不同的处理方法和处理时间、角质层的完整程度和观察数量等均可以影响植物表皮特征的正确获取。

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 NLR of 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.