The arboretum is a great place to see how diverse eucalypts can be, with one feature being whether/how they shed their bark each summer.
Eucalyptus leptopoda; Merredin mallee (formerly Tammin mallee, pegs 472 to 475) is a lovely plant that is common on gravel and sandplain soils in the Eastern Wheatbelt. There they have grey/white smooth bark with darker strips of old bark. Today I noticed long shreds of shed bark up to 3 metres long hanging down from upper branches of plants in the arboretum, with light copper new bark that will gradually turn grey white.
Mallees are adapted to cope with regular fires by regenerating from a large lignotuber root, but the arboretum specimens have shaggy bark stem bases and long spindly stems that are beginning to snap.
For more information on eucalypts you can’t go past the brilliant book "Eucalypts of Western Australia’s wheatbelt" by Malcolm French.