Blue gum tree yields blush wood.

With its pale blue bark and attractive light pink heartwood, blue gum has attributes which make it appealing to a wide variety of users. Known as Eucalyptus globulus, blue gum is a relative of karri and jarrah, the species of eucalyptus covered in October's Wood of the Month.

The veneer from the blue gum species has become increasingly popular with furniture designers and architects. Marketed as blush, the wood has a pinkish hue. Blue gum also yields a very unusual burl.

Jim Dumas, owner of New York-based Certainly Wood, describes the burl as "resembling a bowl of popcorn. It is not your typical burl."

The general characteristics of the tree include a pink or pale yellow brown heartwood. Its sapwood is usually a gray-white. The grain is often interlocked and texture can be medium coarse. The trees yield the oil but the timber itself is without odor or taste. Gum veins in some trees can affect the look of the grain.

In addition to residential furniture and architectural woodwork, uses include pallets, fenceposts, general construction, utility plywood, flooring, pulp and paper products, lumber and veneer. While its heartwood is moderately resistant to decay, the sapwood is liable to attack by termites and powder-post beetles.

Prolific species

Blue gum is typical of many eucalyptus species in that it is an extremely fast growing tree. "The rapid growth of eucalypts like the mountain ash, river red gum, and the Tasmanian blue gum (Eucalyptus globulus) has caused them to be widely planted throughout the tropics and subtropics, both for timber and for fuel," said author Herbert Edlin in the "Illustrated Encyclopedia of Trees." He added that the various species have also been cultivated to provide railway fuel.

In South Africa, the trees are used for timber and paper pulp. "The pioneer work on conversion of eucalypt timber into paper pulp was carried out in Australia and commercial production of good quality writing and printing papers began in 1838 in Tasmania."

Greedy nature

Unfortunately the prolific nature of the tree has a downside too. In some areas where it has been transplanted, its rapid growth has been seen as encroachment on the native species.

According to Edlin, "California saw the first invasion of the United States by eucalyptus in the 1880s. The blue gum was widely planted with the fanciful notion that it would absorb the 'noxious gasses' which were then supposed to be the cause of malaria. The blue gum did so well it gave the whole gum-tribe a bad name," said Edlin. "It seeded itself everywhere and filled good ground with its greedy shallow roots. Nonetheless it looked splendid, and still does, its blue-rinsed tresses and chaotically shaggy forking trunk mingling with the native oaks and pines."

Edlin wrote that while Californians might dislike the "greedy" nature of the tree, in some parts of the world the blue gum offers a bounty. In Ethiopia, for example, the tree was prized for its fast growing powers and is credited with saving the capital city of Addis Ababa in the last century. With the native trees harvested into extinction, blue gum provided the city with a source of fuel.

Valuable oil

Blue gum is one of the many species of eucalyptus, along with Eucalyptus salicifolia, that has non timber uses.

The leaf glands of the trees are filled with an extremely distinctive smelling oil. The oil is extracted from the leaves by steam distillation and used to produce all sorts of products and medicines. The oil has a camphor smell and a spicy taste. It is used in expectorants for treating colds, coughs, and bronchitis.

Blue gum is also planted strictly for decorative purposes as an ornamental tree.

Family Name

Eucalyptus globulus of the Family Myrtaceae

Other Names

Southern blue gum, Tasmanian blue gum, Australian blue gum, blue gum, blush.

Height/Weight

Height at maturity can reach 250 feet, but average height is 150 feet with trunk diameters of 3 to 5 feet. Weight varies between 48 to 52 pounds per cubic foot.

Properties

The wood needs care during seasoning to avoid distortion and splitting. It is prone to checking with some tendency to warp and collapse. The wood is also heavy. It saws well, but torn grain can be a problem when dressing quartered faces. To rotary peel it is necessary to heat bolts. Irregular grain can pose problems with cutting surfaces. Experts advise to keep cutting surfaces sharp.