The more than 700 species of eucalyptus are mostly native to Australia, and a very small number are found in adjacent areas of New Guinea and Indonesia. One species, Eucalyptus deglupta, ranges as far north as the Philippines.everal eucalypt species are among the tallest trees in the world. Eucalyptus regnans, the Australian 'mountain ash', is the tallest of all flowering plants (angiosperms); today, the tallest measured specimen named Centurion is 99.6 m (327 ft) tall.