中文摘要：

在叶子的结构的进化变化在脉管的植物的解剖和生理学上有影响深远的效果，导致词法差异和种类扩大。人们长对早叶子的形态学的性质的问题感兴趣并且他们怎么被达到。euphyllophytes 的至少五个系能在早泥盆纪石块植物之中被认出(Pragian 年龄， ca。410 妈以前) 华南。他们的不同的叶先锋或分支叶建筑群被相信预示真有不同脉络模式和配置的 megaphylls，显示 megaphylls 的多重起源由早泥盆纪发生了，比早得多以前被认出了。除了在 euphyllophytes 的 megaphylls， laminate 像叶子的附器(孢子叶或苞) 在几个远地相关的早泥盆纪植物系独立地发生了，可能作为对象高大气的 CO2 集中那样的生态的因素的回答。这是在早植物的会聚的进化的一个典型例子。

英文摘要：

Evolutionary changes in the structure of leaves have had far-reaching effects on the anatomy and physiology of vascular plants, resulting in morphological diversity and species expansion. People have long been interested in the question of the nature of the morphology of early leaves and how they were attained. At least five lineages of euphyllophytes can be recognized among the Early Devonian fossil plants （Pragian age, ca. 410 Ma ago） of South China. Their different leaf precursors or ＂branch-leaf complexes＂ are believed to foreshadow true megaphylls with different venation patterns and configurations, indicating that multiple origins of megaphylls had occurred by the Early Devonian, much earlier than has previously been recognized. In addition to megaphylls in euphyllophytes, the laminate leaf-like appendages （sporophylls or bracts） occurred independently in several distantly related Early Devonian plant lineages, probably as a response to ecological factors such as high atmospheric CO2 concentrations. This is a typical example of convergent evolution in early plants.