It appears that part of this problem is caused by the tendency of the southern African Schoenus to form hybrids with each other.

[2] Due to a lack of evidence, it is unclear whether S. riparius forms hybrids with other southern African Schoenus species.

[3] Other notable genera in tribe Schoeneae include Lepidosperma, Oreobolus, Costularia, Tetraria and Gahnia.

[3][1] Southern African Schoenus were once classified as Tetraria; however, based on molecular and morphological differences, we now know that the two groups are evolutionary distinct.

[6] Schoenus riparius has been found growing in wet sites on the Cape Peninsula of South Africa.