The Rainbow Eucalyptus tree is a strikingly colourful eucalypt which originated from South East Asia (the native distribution covered: New Britain, New Guinea, Ceram, Sulawesi and Mindanao) (1). It is a member of the family Myrtaceae, and it can now be found growing throughout the tropics, because as well as being beautiful, it is a very fast growing timber species and is also used as a shade tree for growing coffee. The multi-coloured bark is produced by the shedding of patches of bark, which first reveal a bright green inner bark. This then changes to give blue, purple, orange and maroon tones as it presumably dries out and is eventually shed.
I am not sure why the colours occur; perhaps they are related to the essential oils which eucalyptus trees contain. I took these photographs of a tree which was in the Headquarters of the lovely Doi Sutep-Pui National Park, located near the city of Chiang Mai in northern Thailand.
I discovered another WordPress blog – Ink Chromatography – which features this tree and is well worth reading (2).
1) Eucalyptus deglupta. http://www.worldagroforestry.org/treedb2/AFTPDFS/Eucalyptus_deglupta.pdf
2) Trees in Polychrome. http://inkchromatography.wordpress.com/2011/12/29/trees-in-polychrome/