A tree to 180 ft in the wild state; bark, except near the base, shed in long, thin ribbons which expose a smooth, grey or bluish surface. Juvenile leaves opposite, stalkless and often stem-clasping, oblong-ovate to oblong-lanceolate, 21⁄2 to 6 in. long, vividly silver-glaucous. Adult leaves alternate, lanceolate or sickle-shaped, 4 to 12 in. long and 1 to 13⁄5 in. wide, green and glossy, leathery. Flowers usually solitary in the leaf-axils, more rarely in twos or threes; buds glaucous, up to 1 in. or more long, top-shaped, ridged and wrinkled. Fruit hemispherical to top-shaped, up to 3⁄4 in. long and 11⁄4 in. wide, with a wide, thick disk.
Native of Tasmania, also found in one small area on the mainland; discovered in 1792 and introduced to Europe soon after. The first large-scale plantings outside Australia were made in the fifties and sixties of the last century and since then the blue gum has become one of the most widely planted of all trees in warm temperate and subtropical climates. In our climate it is definitely tender, but thanks to its rapid growth it is able to attain a remarkable size before succumbing, as it usually does, to a severe winter. Elwes and Henry record that a tree in Jersey, planted in 1862, attained in thirty years the dimensions of 110 × 103⁄4 ft, but was killed in the great frosts of 1894-5. A similar fate has more recently befallen many large trees, both here and in the Mediterranean region, after abnormally hard winters. The cost – and often the damage to other trees – entailed in removing such bulky corpses needs no emphasising.
At the present time the largest specimens on record are all in Eire. These are (all measured 1966): Powerscourt, Co. Wicklow, 115 × 83⁄4 + 7 ft and 95 × 91⁄2 ft; Killiney Hill Road, Shankhill, Co. Dublin, 102 × 91⁄4 and 96 × 7 ft; Ashbourne House, Co. Cork, 100 × 12 ft; Derreen, Co. Kerry, three of about the same size, the largest 98 × 141⁄2 ft.
E. bicostata Maiden & Simmonds Eurabbie. – A close ally of E. globulus from the mainland of S.E. Australia, where it ascends to 3,500 ft. It is likely to be hardier than the blue gum but is at present little known in cultivation. There is an example at Mount Usher, Co. Wicklow, measuring 42 × 21⁄2 ft (1966).