Eucalyptus viminalis (PROTA)
|Geographic coverage Africa|
|Geographic coverage World|
|Forage / feed|
Eucalyptus viminalis Labill.
- Protologue: Nov. Holl. pl. 2: 12, t. 151 (1806).
- Family: Myrtaceae
- Chromosome number: 2n = 22
- Manna gum, ribbon gum (En).
- Eucalipto com folhas de vimeiro (Po).
- Mkaratusi (Sw).
Origin and geographic distribution
Eucalyptus viminalis is widely distributed in south-eastern Australia, from Tasmania through South Australia and Victoria to the border of New South Wales with Queensland. In tropical Africa it is known to be planted in Ethiopia, Uganda, Kenya, Tanzania, Zimbabwe, Madagascar and Mauritius. It is widely planted in South Africa.
The wood is used for poles, tool handles, shingles, indoor construction, flooring, boards, panelling, interior trim and joinery. It is suitable for ship and boat building, vehicle bodies, furniture, ladders, sporting goods, veneer, plywood, boxes, crates and particle board. The wood is also used as fuelwood and for paper making.
Eucalyptus viminalis is planted as an ornamental and shade tree, and in shelter belts and windbreaks. It is a bee forage. Branchlets have been used for weaving. A decoction of the leafy twigs is used in baths against rheumatism in the legs.
The heartwood is pale yellow or pink, and is not clearly demarcated from the sapwood. The grain is usually straight, texture coarse. The density is 670–940 kg/m³ at 12% moisture content. The wood is difficult to dry without degrade, because it tends to check and warp, but proper stacking can reduce this tendency to a minimum. Strong collapse may occur, but reconditioning by steaming is possible. The rates of shrinkage from green to oven dry are high: 5.2–13.0% radial and 9.7–31.0% tangential.
The wood is tough, hard and moderately strong to strong. At 12% moisture content the modulus of rupture is (106–)140–183 N/mm², modulus of elasticity 11,500–17,800 N/mm², compression parallel to grain (47–)63–76 N/mm², shear 8–11 N/mm², cleavage 14–27 N/mm and Chalais-Meudon side hardness 6.0–7.8. Once dried, the wood is not stable in service.
The wood is fairly difficult to saw and plane, but African plantation trees give much better quality sawn wood than Australian native trees. Quartersawing is recommended. The wood may split on nailing and screwing, and pre-boring is recommended. The wood is not durable, being susceptible to attacks by termites and marine borers. The sapwood is susceptible to Lyctus borers. The heartwood is extremely resistant to impregnation with preservatives, the sapwood is permeable to moderately resistant.
Eucalyptus viminalis is considered to have potential to become more important as a source of pulp for paper making. Wood from 10-year-old trees from Australia had fibres 0.83 mm long, with a diameter of 20 μm. The wood contained 44% cellulose, 22% glucuronoxylan and 29% lignin. A bleached kraft pulp yield of 54% was obtained, with 3.8 m³ wood needed to obtain 1 t of bleached pulp. Compared to pulps from Eucalyptus globulus Labill. and Eucalyptus grandis W.Hill ex Maiden, which are currently the main sources of Eucalyptus pulpwood, pulp from Eucalyptus viminalis had a high strength, high opacity and low porosity, making it especially suited for wood free printing and writing papers and specialty papers.
In Ethiopia leaves yield 0.8% essential oil, with as main components 1,8-cineole (50.9%), α-pinene (28.2%), globulol (5.1%) and limonene (4.3%). The leaves of Brazilian trees contain 1.3–1.8% essential oil, with 1,8-cineole (84–87%) as main component. The essential oil content is highest in the summer season, when temperature and humidity are high.
- Evergreen, large tree up to 50(–90) m tall; bole up to 120(–150) cm in diameter; bark surface white or yellowish white, smooth or rough; crown large, open.
- Leaves alternate, simple and entire; stipules absent; petiole rounded or slightly flattened, 1–2.5 cm long; blade lanceolate or narrowly lanceolate, 12–20 cm × 1–2.5 cm, acuminate at apex, glabrous, green, pinnately veined, aromatic when crushed.
- Inflorescence an axillary, simple, umbel-like dichasium, 3- or 7-flowered; peduncle angular or flattened, 4–13 mm long.
- Flowers bisexual, regular; pedicel up to 4 mm long; flower buds ovoid, divided into a hemispherical or campanulate hypanthium (lower part) 2–3 mm × 3–5 mm, and a conical or hemispherical operculum (upper part) 3–4 mm × 3–5 mm and shed at anthesis; stamens numerous; ovary inferior, 3–4-celled.
- Fruit a thin-walled hemispherical to globular capsule 5–8 mm × 5–9 mm, enclosed in a woody hypanthium, opening with 3–4 exserted valves, many-seeded.
- Seeds irregular, grey to black.
- Seedling with epigeal germination.
Other botanical information
In Tanzania and Zimbabwe Eucalyptus viminalis has shown rapid growth in the early stages. In South Africa annual height growth was 0.9–1.8 m. In Madagascar trees 13–15 years old reached a height of 25–30 m.
Eucalyptus comprises about 800 species, endemic to Australia, except for about 10 species in the eastern part of South-East Asia. Many Eucalyptus species are cultivated outside their natural distribution area, in tropical, subtropical and temperate regions, because of their rapid growth and adaptation to a wide range of ecological conditions. In Africa Eucalyptus globulus has long been the most important Eucalyptus species, but its importance has declined, although it is still important in cooler climates. Nowadays the main commercial species in Africa are Eucalyptus grandis in more fertile locations, Eucalyptus camaldulensis Dehnh. in drier regions, and Eucalyptus robusta Sm. in tropical regions.
Eucalyptus is divided into several subgenera (7–10, depending on the author), which are subdivided into many sections and series. The results of phylogenetic studies within Eucalyptus suggest that the genus is polyphyletic, hence not of a single evolutionary origin, and consequently it has been proposed to divide the genus into several distinct genera. This has not yet been done, mainly because of the nomenclatural whirlpool this would bring about. Eucalyptus species hybridize easily, which adds to the taxonomic complexity.
Eucalyptus viminalis it is planted up to 3400 m altitude, in areas with a mean annual rainfall of 500–2500 mm, a dry season of 0–5 months, a mean annual temperature of 10–18°C, a mean maximum temperature of the warmest month of 16–32°C and a mean minimum temperature of the coldest month of 0–8°C. It is not very drought resistant. It grows best in valley bottoms on alluvial soils or podzolic sands with a clayey subsoil, and tolerates slightly saline soils. In Ethiopia it is planted on well-drained, deep soils. Eucalyptus viminalis is resistant to fire.
In Ethiopia Eucalyptus viminalis is grown in homesteads and woodlots, and along paths. It is propagated by seed. The 1000-seed weight is 2.5–5 g. Seed can be stored for several years in airtight containers under dry and cold conditions. No pre-treatment is needed for sowing. Germination takes 5–6 days, and the seedlings can be planted out in the field after 5–6 months. The tree coppices well. When the wood is to be used for pulping, coppice rotations of 6–8 years are applied.
In South Africa the tree is severely attacked by the eucalyptus snout beetle Gonipterus scutellatus, resulting in the species being abandoned as a commercial species in the country. Both larval and adult stages cause damage, especially by feeding on the leaves. Repeated defoliation leads to stunted growth, and trees may split and die. Adults, larvae and eggs are carried on planting material and attached soil, whereas adults may also spread by flying. In Mauritius biological control using the egg parasite Anaphes nitens has been successful in reducing attacks on Eucalyptus viminalis. Chemical treatment is not recommended because of its adverse effects on honey bees visiting the trees. Gonipterus scutellatus is of Australian origin, and is recorded to be present in Kenya, Uganda, Malawi, Zimbabwe, Mozambique, Madagascar, Mauritius, South Africa, Swaziland and Lesotho. Differences in susceptibility exist between Eucalyptus spp., with Eucalyptus viminalis belonging to the more susceptible species.
For southern Africa, where the eucalyptus snout beetle is prevalent, the development of genotypes resistant to this pest would be of great importance.
Eucalyptus viminalis yields wood that is not strong, not durable and fairly difficult to handle. However, it is a suitable tree for regions where frost is common, and in Ethiopia it is considered a good alternative for Eucalyptus globulus at higher altitudes. Furthermore, Eucalyptus viminalis has good prospects for paper making and as a source of cineol-rich essential oil.
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- M. Brink, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Correct citation of this article
Brink, M., 2008. Eucalyptus viminalis Labill. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 12 November 2020.
- See the Prota4U database.