浮萍（学名：Lemna minor），天南星科青萍属水生植物，别称青萍。广布于世界各地，池塘、湖泊内常见。

多年生漂浮性水生植物，植物体为倒卵形或长椭圆形叶状，成片浮于水面，两面浅绿色，直径约3cm，下面有根一条；叶状枝自植物体下部生出，对生；夏季开白色花，着生在叶状体的侧面。

Lemna minor, the common duckweed or lesser duckweed, is a species of Lemna (duckweed) with a subcosmopolitan distribution, native throughout most of Africa, Asia, Europe and North America, occurring everywhere that freshwater ponds and slow-moving streams occur, except for arctic and subarctic climates. It is not reported as native in Australasia or South America, though is naturalised there.