Ironbark is a common name for many different species of trees, but is most often associated with eucalyptus. These trees are native to Australia, where they have grown for millions of years. They are recognized by their grooved bark, lance shaped, evergreen leaves, and showy clusters of bright pink, cream or pure white flowers that appear in winter and spring. Ironbark is very drought resistant, and requires little water to survive, but will live in the most waterlogged areas as well. The wood of this tree is extremely hard and durable and is used to make high quality dark red lumber.
These trees can reach as much as 200 feet (60 m) tall and will tolerate a wide range of growing conditions. The best growth is obtained when given full sun and rich loam, although these trees are known for their ability to withstand very poor, arid soil. They will also live in very wet areas; these trees are sometimes planted in waterlogged locations to help drain the excess water.
All species of ironbark are difficult to start from cuttings. The small, black seeds germinate quite easily, however, and can be collected from the wine glass shaped seed pods as soon as they have dried and turned brown. When planted in potting soil and kept moist, they will usually sprout within a few weeks. The seedlings can be transplanted in late spring or summer in cold winter areas, although in Australia they can be set out any time of year. Seedlings and small trees are sold in larger garden centers in the U.S. and Europe where they are planted as landscape trees.
These types of trees have gained attention from environmentalists in recent years because they are fast growing and have many uses. In addition to being used as lumber, they make high quality, slow burning firewood for wood stoves. Ironbark trees also produce an oil used in natural cleaning products and insecticides. In addition, ironbark trees contain cineole oil used in natural lotions, inhalants, and antiseptic products and is said to ease muscle aches and pains.
Like most other tree species, ironbark is prone to certain diseases. Armillaria root disease is the most common of these; it kills the trees by form girdling them and strangling the roots. A fungal disease called Piptoporus australiensis can infect these trees, causing a pink fungus to form on the bark. Sawfly larvae have been known to occasionally attack ironbark trees, although they are not often damaged by harmful insects.