沼兰属（学名：Malaxis）是兰科下的一个属，为陆生兰或附生兰。该属共有约300种，遍布全球热带与亚热带地区。

Malaxis, commonly called Adder's mouth, is a genus of terrestrial and semiepiphytic orchids. The generic name signifies "smooth" and alludes to the tender texture of the leaves. There are approximately 182 species, found mostly in tropics but with some species in temperate regions.