Diphasium is a genus of lycophytes in the family Lycopodiaceae.

In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is placed in the subfamily Lycopodioideae.

[2] Some sources do not recognize the genus, sinking it into Lycopodium,[3] others include it in Diphasiastrum.

[1] Diphasium species are mostly native to the temperate southern hemisphere, but extend northwards into Central America and the Caribbean.

[1] As of June 2024[update], the Checklist of Ferns and Lycophytes of the World recognized the following species:[1]