 "Prostanthera lasianthos" is the largest member of the mint bush genus "Prostanthera".Highly variable in habit, it ranges from a tree in sheltered forest to a shrub in exposed montane areas.Arranged oppositely (arising in pairs) along the stems on 0.6–1 cm long petioles, the dark green lanceolate to ovate leaves are 4 to 12 cm (sometimes 15 cm ) long and about 1.0-3.2 cm wide and taper to an acute apex.