Tetraphis is a genus of two species of mosses (Bryophyta). Its name refers to its four large peristome teeth.
The sex of Tetraphis shoots can transform depending on the shoot density. When a colony is sparse femaleâÂÂgemmae-producingâÂÂshoots dominate. When the colony is sufficiently dense they transform into male shoots.
This density-dependent sexual reproduction strategy is common in fish but Tetraphis is the first moss in which this has been documented.