[2] It is endemic to the south-west of Western Australia.

[3][4] It grows in moist to wet soils, in swamps, creeks, seasonally wet sites, and near road ditches.

[6][7] This problem of two species with the same name was corrected by Kurt Sprengel in 1825 when he published the name, Restio diffusus, for this species.

[6][8] In 1998, Lawrie Johnson and Barbara Briggs transferred R. diffusus to the genus, Leptocarpus.

[9] In 2001 in consideration of IUCN rules, the species Leptocarpus diffusus was renamed Leptocarpus laxus by Barbara Briggs.