波喜荡草科只有1属—波喜荡草属（Posidonia）3-9种，都是生长在海水中的咸水生植物，主要分布在地中海和澳大利亚沿海。

2006年在西班牙的地中海岛屿伊维萨岛南部发现了大约有8千米长的大范围波喜荡草生长区域，可能已经持续有10万年之久。

因为其名称源自希腊神话中的海神波塞冬，所以也被翻译为海王神草。

Posidonia is a genus of flowering plants. It contains two to nine species of marine plants ("seagrass"), found in the seas of the Mediterranean and around the south coast of Australia.

The APG system (1998) and APG II system (2003) accept this genus as constituting the sole genus in the family Posidoniaceae, which it places in the order Alismatales, in the clade monocots. The AP-Website concludes that the three families Cymodoceaceae, Posidoniaceae and Ruppiaceae form a monophyletic group. Earlier systems classified this genus in the family Potamogetonaceae or in the family Posidoniaceae but belonging to order Zosterales.