Angophora inopina is a tree, often multi-stemmed, that typically grows to a height of 8 m (26 ft) and forms a lignotuber.

[3][4][5][6] Angophora inopina was first formally described in 1997 by Ken Hill from specimens collected near Charmhaven in the same year.

[6][7] The specific epithet (inopina) is from the Latin inopinatus, meaning "unexpected", referring to the occurrence of this previously undescribed species near Sydney.

[6][8] Charmhaven apple grows sandy soil over sandstone in woodland with a dense, shrubby understorey.

The main threats to the species are habitat loss and fragmentation, changes to the water table, frequent fires, trampling and competition from weeds.