93% of the 4,000 square miles of the Greater Blue Mountains Area is forested with eucalypt vegetation. When the temperature rises, the oil of these eucalyptus trees evaporate into the air, casting a blue haze over the landscape. This phenomenon gave the region its name. It is estimated 100 eucalypt species grow in the Blue Mountains. The tallest at nearly 200 feet is the blue gums. This distinctive white gum averages 50 feet in height.
