Schoenus rigidus is a species of sedge endemic to locations near central regions of the southern coast of South Africa.

[1] The southern African Schoenus have a tendency to form hybrids with each other based on preliminary evidence, which partially explains why they can be difficult to identify.

[3] Schoenus rigidus is a species in family Cyperaceae, tribe Schoeneae, which is a clade that includes genera such as Costularia, Gahnia, Lepidosperma, Oreobolus and Tetraria.

[1] Species from the southern African Schoenus were once included in the genus Tetraria; however, both molecular and morphological evidence suggests that the two genera are evolutionary distinct.

[6] To ensure that this group of sedges is monophyletic (i.e. the genus only has closely related species), the southern African Tetraria were transferred into Schoenus.