Species

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Acacia melanoxylon or Blackwood, is a wattle tree in the family Mimosaceae. It is common throughout the east coast of Australia across a wide range of environments. It has many uses, both in the present and traditionally by native peoples. There are a few species with similar characteristics to Blackwood that are also used for instruments, some occurring off the Australian continent.

Description

Blackwood can be a small to tall tree that can grow to 40m tall and have a diameter of 1.5m (Doran and Turnbull 1997). The bark is usually hard and fissured but occasionally may be flaky (left). Adult leaves are dark green with multi-veined phyllodes and juveniles have bi-pinnate compound leaves. The inflorescence is made up of globular flowerheads on peduncles in racemes. Flower colour ranges from off white to pale yellow. Pods are light brown, curled and contain seeds arranged longitudinally (Maslin 2001). Seeds are doubly encircled by a red funicle, often thought to aid in bird dispersal (Glyphis et. al. 1981). Wood colours range from dark reds and browns to golden brown, orange and yellow, some having deep purple and black streaks.

Image of PhyllodesImage of Bi-pinnate foliageImage of Seeds and SeedlingsImage of Mature Tree

Distribution/Habitat

The natural range of Blackwood extends from Northern Queensland along the east coast to far south-west Victoria and Tasmania, also naturally occurring in isolated pockets in South Australia. Blackwood is common in soils that exceed 600mm of rainfall but develops best on deep soils, especially in tall forests and ‘jungle’ pockets in mountain valleys (Costermans 1994). This species is usually an understorey species to Mountain Ash (Eucalyptus regnans), Messmate (E. obliqua), Swamp Gum (E. ovata), Narrow-leaved Peppermint (E. radiata), Broad-leaved Peppermint (E. dives), Manna Gum (E. viminalis) and Mountain Grey Gum (E. cypellocarpa) in mixed species sclerophyllous forests (Viridans Biological Databases 2011). It will also grow within stands of Myrtle Beech (Nothofagus cunninghamii) in Cool Temperate Rainforest but sometimes occurs as the dominant strata in areas that have been subject to forest clearing (pers. obs.).

Natural distribution of Blackwood (Maslin 2001):

 

Map displaying species distribution

Life-cycle

Blackwood produces seeds which have been known to germinate after 100 years in the soil (from a site near Warnambool Victoria where Blackwood germinated after railway construction from within farmland that had been cleared for over 100 years) and after 10 years in sea water (Cambage 1915). In the natural environment, fire aids seed germination (Wilkinson and Jennings 1994). Young seedlings have bi-pinnate foliage that is thought to reduce predation from herbivores and also increases its growth rate enabling greater competition for light and space (Cambage 1915). Blackwood trees can grow for over 150 years before they commonly rot out, are eaten by ants, blow over or are struck by lightning. Once a tree perishes it enables light to penetrate through the canopy (in dense areas) and provides conditions suitable for seed germination.

Utilisation/Properties

Blackwood has had a long history of utilisation by indigenous peoples within Australia (Kean 1991). The seeds are high in protein and can be ground up to make flour and the timber has been used to make spears and boomerangs (Whitesell 1964; Daehler et al. 1999). Blackwood is easily workable and is a common material in furniture and kitchens. More recently it has been recognised as a quality timber for instruments, having similar tonal properties to the more traditional tonewood, Acacia koa (Morrow 2007). Blackwood has good bending properties and has a low reduction in size when drying. It has ideal density and tonal properties for necks, backs and sides and has aesthetic properties that make it also ideal for headstock veneers, bindings and inlays. Blackwood has been successfully used in instruments such as electric and acoustic guitars, ukuleles, violins, mandolins, cellos, weissenborns, drums and stomp boxes.

Similar species

Acacia implexa (Lightwood)

Lightwood is morphologically and genetically similar to Blackwood (Maslin 2001; Miller et al. 2011) and has a similar distribution but only grows to 15m tall. Its timber is of a similar colour to blackwood but is much denser and rarely grows with a clean straight trunk. Recently it has been used as bridges and fingerboards for guitars in Australia (Morrow 2007).

Acacia koa (Koa)

By far the most similar species to Blackwood in terms of timber, tonal properties and growth form, is the Hawaiian endemic Koa. Koa naturally occurs on the four largest of the Hawaiian Islands; Hawaii, Maui, Oahu and Kauai (Whitesell 1964). Growth form, inflorescence characters and timber properties are very similar with Blackwood, differing mainly in leaf and pod characters (Pedley 1975; Waner et al. 1990; Rock 1913; Kidman et al. 2008). The genetic sequence of one region (ETS) of DNA (Nuclear Ribosomal) showed only 6 base pair differences between Koa and Blackwood in an unaligned sequence length of 478 base pairs (Kidman et al. 2008). This study suggested that Blackwood and Koa have diverged relatively recently from a common ancestor.

Traditionally Koa was used by native Hawaiians to make canoes, spears and ukuleles amongst other things (Whitesell 1964). The timber is very aesthetically pleasing, with beautiful colours and figure that are also very similar to Blackwood (Rock 1913). More recently this species has become exploited and it’s availability for instrument making is becoming increasingly limited. As an instrument timber, this species is renowned for its rich warm tonal properties that become louder and more refined with increased playing.

Acacia heterophylla

Acacia heterophylla is native to Reunion Is. and Mauritius but has also become naturalised in Madagascar (Du Puy 2001). It is almost identical to Koa and its leaf shape and size, inflorescence characters and growth form is more similar to Koa than what Koa is to Blackwood (Rock 1913; Pedley 1975; Kidman et al. 2008). This species has a very limited distribution and any commercial harvesting would be unsustainable.

Links

Evaluation of Australian timbers for use in musical instruments:
http://www.gottsteintrust.org/media/AMorrow.pdf

Acacia melanoxylon speciesinformation:
http://www.worldwidewattle.com/infogallery/utilisation/acaciasearch/pdf/...

References

Cambage, R. H. 1915. Acacia seedlings (part 1 of 3). New South Wales:Royal Society of New South Wales Viridans Biological Databases 2011. Flora Information System (FIS). Viridans Biological Databases Pty Ltd, East Bentleigh, Victoria.                 
Costermans, L.F. 1994. Native trees and shrubs of south-eastern Australia. Reed New Holland, Sydney. Glyphis, J. P., Milton, S. J. and Siegfried, W. R. 1981. Dispersal of Acacia cyclops by birds. Oecologia 48:138-141.
Daehler, C. C., Yorkston, M., Sun, W. and Dudley, N. 1999. Genetic variation in morphology and growth characteristics of Acacia koa in the Hawaiian Islands. International Journal of Plant Sciences 160: 767-773. Kean, J. 1991. Aboriginal Acacia relationships in central Australia. Records of the South Australian Museum (Adelaide) 24:111-124.
Doran, J. C. and Turnbull, J. W. 1997. Australian trees and shrubs: species for land rehabilitation and farm planting in the tropics. ACAIR Monograph No. 24. Australian Centre for International Agricultural Research, Canberra. Kidman, J. K., Brown, G. K., Ladiges, P. Y. and Murphy, D. J. 2008. A phylogenetic position of the extra-Australian phyllodinous acacias. Honours project. University of Melbourne.
Du Puy, D. J., Labat, J. N. Rabevohitra, R., Villers, J. F., Bosser, J., and Moat, J. 2001. The Leguminosae of Madagascar. Kew Publishing p. 231-232. Maslin, B. R. 2001. Flora of Australia 11B.
Miller, J. T., Murphy, D. J., Brown, G. K., Richardson, D. M. and Gonz ́lez-Orozcol, C. E. 2011. The evolution and phylogenetic placement of invasive Australian Acacia species. Diversity and Distributions. 17: 848–860 Wagner, W. L., Herbst, D. R. and Sohmer, S. H. 1990. Manual of the flowering plants of Hawaii. University of Hawaii Press : Bishop Museum Press 1:640-643.
Morrow, A. 2007. Evaluation of Australian timbers for use in musical instruments. Gottstein Fellowship Report. The National Educational Trust of the Australian Forest Products Industries. Whitesell, C. D. 1964. Silvical characteristics of Koa (Acacia koa Gray). Pacific Southwest Forest and Range Experiment Station - Berkley, California Forest Service - U. S. Department of Agriculture:1-11.
Pedley, L. 1975. Revision of the extra-Australian species of Acacia subg. Heterophyllum. Contributions from the Queensland Herbarium 18:1-24. Wilkinson, G. R. and Jennings, S. M. 1994. Regeneration from ground-stored seed in the North Arthur Forests, north-western Tasmania. Forestry Commission Tasmania.
Rock, J. F. 1913. The indigenous trees of the Hawaiian Islands.22-35. pers. obs. Kidman, J. K. 2012.