Originating from California, the Blue Oak is a proud specimen tree as well as one of the most drought-tolerant oaks for a Mediterranean climate. Named for the bluish colour of its waxy coated leaves by Scottish botanist, David Douglas, in 1831. Leaves become bluer as the temperature increases and may drop in response to very harsh summers. It is worth visiting the Waite Arboretum in Adelaide to experience the large 90 year old plantings. Medium growth rate.