Prostanthera sericea, commonly known as silky mintbush[2] or walyuwalyu,[3] is a species of flowering plant in the family Lamiaceae and is endemic to inland Australia.

It is an erect shrub with hairy branches, cylindrical leaves and white flowers with mauve or purple streaks.

[3][4][5] Silky mintbush was first formally described in 1926 by John McConnell Black who gave it the name Prostanthera baxteri var.

sericea in the Flora of South Australia from specimens collected near the Birksgate Range during the Elder expedition of 1891.

[6] In 1988, Barry Conn raised the variety to species status as Prostanthera sericea in the journal Nuytsia.