Hymenachne, synonym Dallwatsonia, is a genus of widespread wetland plants in the grass family Poaceae.

[5] They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands.

[7] Hymenachne species are aquatic plants frequently found in marshes and other wet habitats.

The genus was named for the Australian botanists Michael Dallwitz and Leslie Watson.

[15] As of November 2024[update], Plants of the World Online accepted Dallwatsonia as a synonym of Hymenachne.