Eucalyptus is one of seven closely related genera. Eucalyptus, Corymbia, Angophora, Stockwellia, Allosyncarpia, Eucalyptopsis and Arillastrum all belong to the Eucalypt group in the Myrtaceae family.
There are more than 700 Eucalyptus species and most of them are native to Australia. They may take the form of a low shrub or a very large tree. The Australian mountain ash (Eucalyptus regnans) is the tallest of all flowering plants (angiosperms). The tallest measured living specimen is almost 100m high. Only the Giant Redwood (Sequoia sempervirens) is taller, and that is a conifer (gymnosperm). There are two Giant Redwoods in Victoria Park.
The flowers do not have petals but do have numerous fluffy stamens which may be white, cream, yellow, pink or red. The flowers are enclosed in the cup-like base (gum nut) and covered by a cap called an operculum. As the stamens expand, the operculum is forced off. This is one of the features that unite the genus. The name Eucalyptus, from the Greek words eu-, well, and kaluptos, cover, meaning "well-covered", refers to the flowers.
The flowers produce a great abundance of nectar, providing food for many animals.
The leaves usually change as the plant ages and are covered with oil glands. The essential oil extracted from the leaves has medicinal, perfumery and industrial uses. Global production of eucalyptus oil is dominated by the Tasmanian Blue Gum (Eucalyptus globulus).
The Flooded gum (Eucalyptus grandis) is one of the main plantation species grown in tropical and sub-tropical plantations worldwide. It has the potential to achieve some of the highest growth rates of any plantation forestry species and the timber has many end-uses.
The Dubbo Regional Botanic Garden has many examples of Eucalyptus species particularly in the Biodiversity Garden but a Tasmanian Blue Gum (Eucalyptus globulus var. compacta) may be located near the gecko sculpture in the Sensory Gardens.
By Ian McAlister and Karen Hagan