无叶莲科（学名：Petrosaviaceae）也叫樱井草科，是无叶莲目（Petrosaviales）的唯一科，只包括2属—无叶莲属（Petrosavia）和樱井草属（Japonolirion）共4种，分布在中国、日本和东南亚岛屿一带。

1981年的克朗奎斯特分类法将其列在霉草目，1998年根据基因亲缘关系分类的APG 分类法认为应分为两个独立的科—无叶莲科和樱井草科，但无法分入任何一个目，只是直接放在单子叶植物分支之下，2003年经过修订的APG II 分类法将两科合并，但仍然没有能归入任何一目。直到2009年，APG III分类法让其自成一目。

Petrosaviaceae is a family of flowering plants belonging to a monotypic order, Petrosaviales. Petrosaviales are monocots, and are grouped within the lilioid monocots. Petrosaviales are a very small order (1 family, 2 genera, about 5 species) of rare leafless achlorophyllous, mycoheterotrophic plants found in dark montane rainforests in Japan, China, Southeast Asia and Borneo. They are characterised by having bracteate racemes, pedicellate flowers, six persistent tepals, septal nectaries, three almost distinct carpels, simultaneous microsporogenesis, monosulcate pollen, and follicular fruit.