Definition of rusty gum in English:

rusty gum

noun

Australian
  • A tall tree of eastern Australia, Angophora costata (family Myrtaceae), which has smooth reddish bark and small woody fruits, and is common as an ornamental tree in some residential areas; also called smooth-barked apple.

Origin

Mid 19th century; earliest use found in Ludwig Leichhardt (1813–?1848), natural scientist and explorer in Australia.