蕨类植物的生殖方式研究起步较晚，是研究的热点和难点。铁线蕨属中鞭叶铁线蕨系分布广泛，生境类型丰富，研究表明该系中存在自然杂交种和隐性杂交种；且认为无性繁殖习性（顶端鞭状延伸生长成小植株，营养繁殖），能弥补有性生殖隔离带来的适合度降低的缺陷，增加杂交种在自然界中的存活机会，是杂交种在自然界中普遍存在的重要原因。而白垩铁线蕨系源于鞭叶铁线蕨系内部，其顶端并不能延伸为鞭状，仅生长于中国喀斯特地貌和丹霞地貌，其生殖方式尚不清楚。本项目拟在分类学研究基础上，利用核基因片段与叶绿体基因片段，结合染色体倍性分析和配子体发育研究，对白垩铁线蕨系的生殖方式进行综合研究，探索其物种形成与演化历程。

Reproduction research of ferns has become hotspots and difficult spots of biologist perhaps due to its late starting compared to the reproduction research of angiosperm. Series Caudata are widespread and its species appear in many kinds of habitates, where some natural hybrids were proved to be existed. Its typical vegetative reproduction was considered to be the important reason for the widespread of hybrids in natural world, because it can increase the chance for survival of hybrids and reduce the fault--diluting fitness in the competing environment caused by the reproductive isolation. Series Gravesiana, endemic in Karst or Danxia landform of China, is derived from Series Caudata. While its reproduction modes remain unclear. Based on existing taxonomic systems of Gravesiana, this project plans to use nrDNA and cpDNA regions, combining with evidence from chromosome ploidy and development study of its gametophyte, to clarify its phylogeny and reproduction delimitation, and to elucidate its probable evolution process in speciation.