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首页> 外文期刊>International journal of plant sciences >THE ORIGINS AND EARLY EVOLUTION OF THE MEGAPHYLLOUS LEAF
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THE ORIGINS AND EARLY EVOLUTION OF THE MEGAPHYLLOUS LEAF

机译：巨噬叶的起源和早期演化

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摘要

Paleobotanical data, with emphasis on anatomical characters in ferns and seed plants, confirm that the megaphyllous leaf evolved independently several times from the Middle Devonian to the Early Carboniferous. Fernlike cladoxylaleans and aneurophytalean progymnosperms possessed only megaphyll precursors homologous with the small megaphylls of archaeopteridalean progymnosperms. Different trends toward developing a large megaphyll, from the modification of lateral branch systems of some basal euphyllophytes, are shown by the fernlike rhacophytaleans and by the zygopterid and tedelean ferns. Zygopterids, with their tridimensional frond, petiole of the phyllophore type, and annulate sporangia, must be considered as the earliest undisputable ferns while the probably derived tedeleans have evolved toward a convergent filicalean-type of frond. The leaf of other early ferns certainly derived through a minimal change in anatomy from other Devonian euphyllophytes. Early seed plant leaves probably evolved through the modification of an entire lateral branch system of aneurophytalean or stenokolean ancestors. In contrast to ferns, the seed plants early developed broad laminate pinnules with dichotomous nervation. The leaves of ferns and seed plants are not homologous, and fundamental differences in their petiole anatomy support the early divergence of the two groups.
机译：古植物学数据，重点是蕨类和种子植物的解剖特征，证实巨叶叶从泥盆纪中期到石炭纪早期独立地进化了几次。蕨类的cladoxylaleans和厌氧藻类的裸子植物只具有与原翼龙的裸子植物的小叶肉同源的叶肉前体。蕨类鼠李类植物，合翅类和特德莱恩类蕨类植物显示出从一些基底真生植物的侧枝系统改造中形成大型叶肉的不同趋势。具有三维叶状，叶柄型的叶柄和环状孢子囊的Zygopterids，应被认为是最早的无争议的蕨类植物，而可能衍生的泰德兰人已进化为趋于融合的丝状。其他早期蕨类植物的叶子当然是通过解剖学上的最小变化而衍生自其他泥盆纪真生植物。早期种子植物的叶子可能是通过改变厌氧藻或先天ten的祖先的整个侧枝系统而进化而来的。与蕨类植物相反，种子植物较早地发育出带有二分神经的宽叠层针叶。蕨类植物和种子植物的叶子不是同源的，它们的叶柄解剖学上的根本差异支持了这两组的早期分化。

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