Leaves were classified into five age categories, i.e. juvenile (1,
newly formed), expanding (2, expanding but still soft), young
mature (3, fully expanded and firm), old mature (4, fully expanded,
hard leaves with black or yellow spots 20% of leaf area yellow). All age classes were present in G.
robusta and A. acuminata, whereas new and senescent leaves were
found mainly at the beginning and end of the leafing period in P.
fortunei (October and May respectively); at least three or four of
these stages were present for most of the 17-month observation