水龙骨目是真蕨纲中的一个主要分支，包含有超过百分之80的现今蕨类物种。它们在热带、亚热带和温带等地区都可以被发现。这一目的特征有：带有一由茎和裂缝交织成垂直环形的孢子囊；侧面或中心依附的菌裙；绿色、有梗且在地面的配子体。

水龙骨目被认为是蕨类最晚分歧出来的目，基于最近的基因分析。它们大约在一亿年前形成且分歧出来，大概是接在被子植物门分歧之后。

水龙目现在有15科：

The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas. The characteristics of this group include: sporangia with a vertical annulus interrupted by the stalk and stomium; indusia laterally or centrally attached (or lost); gametophytes green, chordate, and surficial.