The Marri tree is one of the most common of the eucalypts found in the south-west forests of Western Australia (WA). It is not found outside of the south west corner of WA. The marri was formerly referred to as Eucalyptus calophylla but in 1995 around 80 eucalypts were transferred to a newly created genus Corymbia. Some botanists prefer to retain the former name. It belongs to a group known as bloodwords because the trunks exude a dark red gum (kino). The term ‘marri’ comes from the Nyoongar aboriginal word for blood. The tree itself was once commonly known as the red gum.
Marri is one of the most important trees in West Australian forests. It produces large amounts of blossom and nectar. When mature, the trees develop large hollows that make highly sought after nesting sites for many species including the endangered black cockatoos, western ringtail possums and owls.
The marri (Corymbia calphylla) belongs to the family of myrtles (Myrtaceae). ‘Corymbia’ comes from the Latin ‘corymb’ referring to the floral clusters which branch from the stem at different levels but terminate at about the same level. ‘Calophylla’ comes from ‘calo’ meaning beautiful and ‘phyllon’ a leaf.
The marri is widely spread in the better watered areas of the south-west. It is an important part of both jarrah and karri forests and also occurs on the coastal plain and in a range of soil types although it prefers moderately fertile soils.
Usually a large tree of up to 40 metres, it can be more shrub-like on poor soils. In mid-summer, despite this being the dry season, the prominent cream flowers are seen outside the canopy. The marri has tessellated (rough) bark which flakes off in small pieces. The bark is grey-brown to dark brown in colour. The buds form on long stalks and in loose clusters of three to seven. The bud cap is hemispherical and two to four mms long. The fruit is large and woody, urn-shaped and 26 to 50mm long. The nuts are an important food source for some species of parrots and cockatoos. The nuts are known locally as ‘honkey nuts’. The honkey nuts inspired May Gibbs to write her stories about the gumnut babies, Snugglepot and Cuddlepie. There are prominent oil glands in the leaves. The leaves have closely packed veins and are dull to shiny dark green on the upper surface and paler below.
The marri is somewhat similar to Corymbia ficifolia and the two species cross easily creating hybrids. There is a rare pink flowered form of the true marri. The timber is the colour of honey. It is not used for construction purposes as it is not a strong timber being full of gum veins and having numerous faults. It is increasingly used for the production of fine furniture and is suitable for the manufacture of pulp.
The marri is an excellent shade tree in open areas but is not so suited to gardens and street plantings. In open areas it forms a rounded tree whereas in a forest situation the side branches are restricted. It tends to repeatedly branch into two, somewhat equal branches and propagates easily from seed.
The marri was known by the Nyoongar people as the ‘medicine tree’. The gum was sprinkled onto wounds to prevent bleeding and was mixed with water as a mouthwash or disinfectant. The tannin in the bark has antiseptic qualities. The powdered gum was used to tan kangaroo skins. The blossoms were soaked to make a sweet tea and the seeds and gum were used as a cure for diarrhoea.