Jarrah

Jarrah (Eucalyptus marginata) is one of the most common types of eucalyptus trees of southwestern Australia. The species' scientific name, marginata, refers to the light-colored vein on the border around its leaves. Because of the similar appearance of worked jarrah timber to the Honduras mahogany tree, jarrah was once called Swan River mahogany after the river system that runs through Perth. Now it is almost exclusively referred to by its aboriginal name.

The jarrah tree grows up to 40 meters (135 feet) high with a trunk up to three meters in diameter, and has rough, grayish-brown, vertically grooved, fibrous bark which sheds in long flat strips. The leaves are often curved, 80 to 130 millimeters (three to five inches) long, shiny dark green above and paler below. The stalked buds appear in clusters of seven to 11. Each bud has a narrow, conical bud cap five to nine millimeters long. The flowers are white and bloom in spring and early summer. The fruits are spherical to barrel-shaped, and nine to 16 millimeters (one-third to two-thirds of an inch) long.

The characteristic eucalyptus bark is not shed in patches as it is with many gums, but it splits into fibrous strips. Jarrah trees are also unusual in that they have a lignotuber, a large underground swelling which stores carbohydrates and allows even young trees to re-grow after a fire. Because they are deep-rooted (as much as forty meters deep), jarrah are drought resistant, able to draw water from great depths during dry periods.

Jarrah blossoms are used to make honey, but its wood is its main use; it is the principal hardwood tree harvested in Oceania for timber. It is a heavy wood, with a specific gravity of 1.1 when green. Its long, straight trunks of richly coloured and beautifully grained termite-resistant timber make it valuable for cabinet making, flooring, and panelling. The finished timber has a deep rich reddish-brown color and an attractive grain. When fresh jarrah is quite workable but when seasoned it becomes so hard that conventional wood-working tools are useless. It is very durable, even in wet and weathered situations, making it a choice structural material for bridges, wharves, railway crossties, ship building, telegraph poles, and paving blocks for European streets.

The jarrah tree is an important element in its ecology, providing numerous habitats for animal life, especially birds and bees, while it is alive, but also in the hollows that form as the heartwood decays, and when it falls, it provides shelter to ground-dwellers such as the chuditch (Dasyurus geoffroii), a marsupial cat.

Jarrah is very vulnerable to "dieback," the algae (once thought to be a fungus) Phytophthora cinnamomi, which causes root-rot.