Rylstone Prostanthera stenophylla is a species of flowering plant in the family Lamiaceae and is endemic to Wollemi National Park in New South Wales.

It is an erect, slender, aromatic shrub with hairy, oblong leaves and small groups of pale bluish mauve to violet flowers.

The flowers are arranged in groups of four to six on short side shoots in leaf axils, with bracteoles 2–2.5 mm (0.079–0.098 in) long at the base of the sepals.

[2][3] Prostanthera stenophylla was first formally described by Barry Conn of the National Herbarium of New South Wales in the journal Telopea in 2006 from specimens collected near Dunns Swamp in 1996.

[3] This mintbush is only known from the Wollemi National Park where it is found in sclerophyll forest dominated by black cypress pine (Callitris endlicheri), snappy gum (Eucalyptus rossii) and Sydney peppermint (E. piperita), growing in sandstone outcrops that are colloquially known as 'pagodas'.