The River Red Gum (Eucalyptus camaldulensis) is a tree of the genus Eucalyptus. It is one of around 800 in the genus. It is a plantation species in many parts of the world, but is native to Australia, where it is widespread, especially beside inland water courses. Oddly, it is named for a private estate garden near the Camaldoli monastery near Naples (L'Hortus Camaldulensis di Napoli), from where the first specimen came to be described. Material from this tree was used by Frederick Dehnhardt, Chief Gardener at the Botanic Gardens in Naples, to describe this species in 1832.
It is a familiar and iconic tree seen along many watercourses right across inland Australia. The tree produces welcome shade in the extreme temperatures of central Australia, and plays an important role in stabilising river banks.
The tree can grow to 45 metres (148 ft) tall; it has smooth bark, ranging in colour from white and grey to red-brown, which is shed in long ribbons. The tree has a large, dense crown of leaves. The base of the bole can be covered with rough, reddish-brown bark. The juvenile and adult leaves are stalked, with the adult leaves broad at the base, tapering to the tip. The adult leaf colour is a dull blue-green. The leaf also contains several to many oil-producing glands in the un-veined areas of the leaf. It is fast growing, and usually grows to 40 to 45 metres (130 to 148 ft) in height, depending on its location. The tree grows straight under favourable conditions, but can develop twisted branches in drier conditions.
River Reds and many other eucalypts have an ominous nickname, "Widow Maker", as they have a habit of dropping large boughs (often half the diameter of the trunk) without warning. This form of self-pruning may be a means of saving water or simply a result of their brittle wood. This is also an efficient way of attracting wildlife that live in the holes formed, which gives the red gum a source of natural fertiliser