Eucalyptus conjures images of Australia, whose old-growth forests primarily consist of this large, strong tree. In the late 19th century, eucalyptus was successfully introduced to California to address the need for timber and railroad ties. Although the trees grew, the resulting species were not quite the same as the originals and could not be extensively used because of splitting and other defects common in young trees but not in the old-growth timbers of Australia. Eucalyptus also grows in South America, where it was imported to Brazil in the early 1900s meant for charcoal, paper and pulp, as well as many other regions of the globe.
Eucalyptus grows primarily in tree form, but many shrub-like species also exist. Trees grow from 135 to 300 feet tall, with trunks 3 to 4 feet in diameter. More than 600 species inhabit the genus, although only about a dozen are in commercial production. Among them are Eucalyptus resinifera, or Australian red mahogany, whose leaves produce the distinctive camphor-like scent associated with eucalyptus. A species called E. obliqua, or figured eucalyptus, carries the intriguing common name messmate stringybark, and E. robusta, known as swamp mahogany, grows in Hawaii.
Eucalyptus heartwood is red to reddish-brown, and darkens as it seasons. Its sapwood is pale cream. The grain of this tree is slightly interlocked, with sometimes ripply or fiddleback patterns. It has a medium to coarse texture. It is moderately resistant to termites, but susceptible to marine borers and pinhole borers. Cut eucalyptus will stay strong and dense for a long time; logs have been known to lie in wet forests for 10 to 20 years without heartwood decay.
Eucalyptus is used for all types of construction, fine as well as utilitarian, light and heavy. It is often made into flooring or objects such as bowls, and traditional Aboriginal didgeridoos are created from eucalyptus logs that have been hollowed out by termites. It is easy to saw, sand, plane and polish, and takes paint well. It is a heavy wood, comparable to oak, which should be taken into consideration when shaping it into furniture.
Eucalyptus is not considered a particularly stable wood due to variations in moisture content. Growth stress, resulting from compression on the inner part of the tree and tension on the outer part, can cause the timbers to buck and split. A condition called "brittleheart," which it shares with other tropical hardwoods, causes microscopic cracks in the heartwood, weakening it. The wood may exhibit pin knots and gum veins that ruin the timber when cut. As it dries, eucalyptus tends to shrink more than other woods, and may warp. However, it can be heavily treated with preservatives, which makes it suitable for products such as large poles and logs for homes.