延药睡莲（学名：Nymphaea nouchali）又名蓝睡莲，为睡莲科睡莲属下的一个种。

Nymphaea nouchali, often known by its synonym Nymphaea stellata, or by common names blue lotus, star lotus, red and blue water lily, blue star water lily is a water lily of genus Nymphaea. It is native to southern and eastern parts of Asia, and is the national flower of Sri Lanka and of Bangladesh. This species is sometimes considered to include the blue Egyptian lotus Nymphaea caerulea. In the past there has been taxonomic confusion with the name Nymphaea nouchali incorrectly applied to Nymphaea pubescens.