Title(s) of Object: Burrawang (Macrozamia communis)
Brief Description of Object:
The genus Macrozamia is endemic to Australia and there are about 25 species. All species have dark green, palm-like fronds arising from a central trunk. In Macrozamia communis, the trunk (called the Caudex) is a thick, soft stem made up of mostly storage tissue with very little true wood. The caudex is very short when growing on shallow soils or on rocky sites, and is quite frequently subterranean.
Macrozamia communis is a medium to large cycad that typically has numerous (20-100) fronds, arranged in a gracefully rounded crown that arches out from the central trunk. The glossy green fronds become a dull grey-green with age and are up to 1.5 m long in fully grown specimens (up to 2 metres long in shaded spots), with rigid, forwardly angled, sharp-pointed leaflets (pinnae) 15–35 cm long, arranged in two regular rows on either side of the central stem (rachis). A prominent whitish callous is present at the point where the pinnae join the rachis.
Burrawangs occur from near sea level up to 300 metres.
Habitat and ecology:
Burrawangs can form extensive colonies as an understorey in wet to dry sclerophyll forests. In proximity to the seashore the plant reaches its maximum population density on stabilised sand dunes in close proximity to the ocean. It also grows in dense stands on steep hillsides and slopes of near coastal ranges and in Bega Valley Shire it can be seen growing principally under a canopy of Corymbia maculata (previously Eucalyptus maculata) or Spotted Gum where it is normally the dominant understorey plant. In its natural habitat it seems to prefer partially-shaded locations under an open Eucalyptus forest canopy.
Individual specimens take 10–20 years to mature and may live for up to 120 years. The Australian environment, including that of the Bega Valley, is fire prone and Burrawangs are adapted to survive such harsh conditions. The caudex is often seen covered in old leaf bases that afford some protection to the plant base, helping to make adult plants fire tolerant. The plant will immediately start to produce new fronds if the old ones are burned off or badly scorched. Seed cones are often formed after fire.
Location of Object:
The Burrawang is located along the Pambula River walking track. The track starts at the mouth of Pambula River, offering lovely views of Haycock Point. Information signs dotted along the way highlight the area’s rich cultural history.
Accessibility of Object:
Located along the Pambula River walking track in Ben Boyd National Park and is always open to the public.
History and Provenance of Object:
Between 510 - 630 million years ago, land plants evolved from aquatic plants, specifically green algae. Molecular phylogenetic studies conclude that bryophytes (non-vascular land plants such as mosses, liverworts and hornworts) are the earliest diverging lineages of the land plants that still exist today.
Vascular plants contain plant tissues (xylem and phloem) that are highly specialized for carrying water, dissolved nutrients, and food from one part of a plant to another. Ferns and all seed-bearing plants have vascular tissues; bryophytes, such as mosses do not. The first vascular plants are estimated to have arisen 420 million years ago, and the first plants with leaves occurred approximately 400 million years ago (ferns and horsetails) during the Devonian Period. The earliest plants with seeds then occurred between 300 and 360 million years ago. Seeds were a very significant evolutionary step in the plant world.
Cycads are plants with a long fossil history and these prehistoric survivors were formerly more abundant, widespread and diverse than they are now. They belong to a very ancient Order of plants named Cycadales that contains three families still existing today, Cycadaceae, Stangeriaceae, and Zamiaceae (the last of these to which the Burrawangs belong), and having changed little since the Jurassic Period some 201.3 - 145.0 million years ago. Although sometimes superficially appearing like palms, cycads evolved before the dinosaurs and many millions of years before palms.
Cycads are gymnosperms – that is - vascular plants that reproduce by means of an exposed seed, or ovule - unlike angiosperms (flowering plants) whose seeds are enclosed by mature ovaries, or fruits. The seeds of many gymnosperms (literally “naked seeds”) are borne in cones and are not visible until maturity. Three orders of gymnosperms were particularly important during evolutionary history: the cycads, the gingkoes, and the conifers. Gymnosperms were dominant in the Mesozoic Era (about 252.2 million to 66 million years ago), during which time some of the modern plant families originated.
Today, there are only about 130 known species of cycads, and all of them are dioecious, meaning that individual plants are either male or female. Gymnosperms were the earliest of the seed plants, and are known as the naked seed plants because the male pollen attaches directly to the female ovule without having to travel down a flower's style and the ovary is not enclosed within a carpel. Their reproductive mechanism is therefore very different from that of flowering plants. Instead, cycads produce cone like structures called strobili, and the pollinated strobili of female plants produce seeds while the strobili of males contain only pollen. Unlike many gymnosperms, cycads depend primarily on insects (usually beetles) to effect pollination rather than wind.
Burrawangs shed their pollen as early as late winter and the cones thereafter remain open. The cones of mature female plants separate vertically and remain open and accessible for several days, allowing pollination to take place. A study by Terry, (2001) provided the first demonstration that specialist pollinators of two different insect orders pollinate a cycad, in this case Macrozamia communis, and showed that both the thrip Cycadothrips chadwicki and the weevil Tranes lyterioides affected pollination. The behaviors of other insect visitors to male and female cones suggested that they are not pollinators.
The intimate interrelationship between Tranes lyterioides and Macrozamia communis is likely to represent an ancient one, as the ancestry of weevils can be traced to at least the Triassic (c. 225-190 million years ago), a time that is contemporaneous with the dawning of the cycads.
With regards to large stands of Burrawang plants, these are thought to be an artefact of Aboriginal burning practices. Anthropologists have hypothesised that the Burrawang was used it as a reliable food source for large social gatherings, and in order to have an abundant supply of seeds they would have burnt the stand well prior to the gathering to encourage synchronous flowering and fruiting. Since the plants respond rather positively to fire, doing this repeatedly would create areas where Burrawangs dominate the understorey (Miles, J. 2019).
The particular significance of this Object:
Macrozamia – from the Greek makros meaning large and Zamia, a genus of cycads.
communis – from the Latin communis meaning common, referring to its abundance in dense communal stands, sometimes dominating the shrub layer.
Many stands of Burrawang located in Eurobodalla and some in Bega Valley are turning yellow and dying which is possibly a result of the root rot fungus Phytophthora sp although this is not yet confirmed, many examples have been observed by botanists in State Forests and National Parks within Bega Valley over the last few years which means they may become less common in years to come (Miles, J. 2019).
The common name for the species is Burrawang, a word derived from the Daruk Australian Aboriginal language and spoken by tribes indigenous to the Sydney and Illawarra regions for whom it provided a food source. In fact, the indigenous meaning of the name of the township known as ‘Narooma’ means ‘Burrawang growing in water’ (Coastal Custodians, 2005).
The seeds of the Burrawang are a good source of starch but are poisonous to eat unless treated. Aboriginal people developed a method of vigorous leaching to remove the toxins. The Cadigal people pounded and soaked the seeds in water for a week, changing the water daily. The pulp was then made into cakes and roasted over hot embers.
An article in the Canberra Times states suggests ‘the leaves, the seeds, and the think fibrous trunk contain traces of a toxin. Aborigines, to whom burrawangs were a ready source of food, removed most of the toxin by pounding the flesh into a flour and washing it for days in a running system’ (Canberra Times, 1990 pg. 24). Interestingly the article continues to explore the possible link between the burrawang toxin and motor neurone disease based on the experiences of a couple of retirees who relocated to the Batemans Bay area during the 1980s. Dr Murray Wallace and his wife June had been an entomologist and botanist respectively during their working lives, who had retired to a property chosen because of its abundance of burrawang palms; which was an opportunity for them to continue their life long passion of studying the mysterious life cycle of the burrawang palm. Within three years after their relocation to Batemans Bay, June developed a creeping paralysis in the legs; later diagnosed as a rare and incurable disease, amyotrophic lateral sclerosis (ALS) (Canberra Times, 1990 pg. 24).
Some time after, Dr Murray stumbled across some research by an English researcher on the Pacific Island of Guam who had observed a remarkably high incidence of a particular motor neurone disease in native population. He found that cycads were a regular part of the native diet, and he suggested the possibility of a link.
Dr Murray decided undertake further research and discovered that during the 1920s a factory was built in Batemans Bay to make starch from burrawang palms. Burrawangs make fine starch, stronger than conventional starch made from rice. In the early 1930s the factory was closed and the building demolished. Dr Murray decided to contact the relatives of any workers, as it was likely that all the workers from the factory had already died, to see if there were any expectedly high occurrences of creeping paralysis.
Dr Murray found more coincidences in further research including studies into Guam disease in other parts of the world (Siberia, Japan, New Guinea, Gulf of Carpentaria and Guam). The findings were consistent suggesting there was a link between the two. Another occurrence in the late 1890s when cattle on the south coast developed “the wobbles”, a paralysis of the back legs was reported by a local paper claiming this was caused by animal consumption of the burrawang palms and adding sheep had also died from the same cause. Dr Murray continued his research into the possible links (Canberra Times, 1990 pg. 24).
The Burrawang specimen located along Pambula river was primarily used as a food source; the seeds and fruit were prepared in conjunction with ceremonial practices and was said to be part of women's business associated with that particular area. There are traditional ceremonial grounds situated nearby. Parts of the burrawang were also used in traditional indigenous medicines (Moore, G. 2019).
The Burrawang located along the Pambula River walking track has the most extensive distribution of any cycad in New South Wales and is most abundant on the south coast where it is also distinguished by being the most southerly of all existing wild cycad species growing on the planet.
Related places, items, collections: (Places, items and collections within the LGA that are related or associated)
Large old cycad on the Bush Heritage block at Brogo. Photo courtesy of Jackie Miles.
This particular example is interesting because it is not located an area where they would naturally occur, and so it is assumed to be planted by Aboriginals many years ago. This assumption is warranted based on what would have been a likely migration route between the coast and Wadbilliga (Miles, J. 2019).
Photo courtesy of Trevor King.
Photo courtesy of Trevor King.
Close up of Burrawang fronts. Photo courtesy of Trevor King.
Burrawang cones. Photo courtesy of Trevor King.
Burrawang seeds. Photo courtesy of Trevor King.
Works depicting/highlighting this object:
Historic photographs of this object:
Historic photographs associated with this object:
Contemporary photographs of this object: (including the name of the photographer and the date and place taken and any copyright restrictions or Creative Commons licenses)
2. PEOPLING AUSTRALIA
Aboriginal cultures and interactions with other cultures
Aboriginal People’s Cultural Heritage and Connections to Bega Valley Shire
3: DEVELOPING LOCAL, REGIONAL AND NATIONAL ECONOMIES
8: DEVELOPING AUSTRALIA’S CULTURAL LIFE
Environment - cultural landscape
Cultural landscapes within the Bega Valley
Working the land in the Bega Valley
Religious life in Bega Valley Shire
Geographically associated places / sites:
Associated / linked places / sites / items / people:
Heritage listings (statutory and non-statutory):
Contributors to this ‘library’:
Research: Trevor King and Jackie Miles
Photographs: Copyright Trevor King
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This Bega Shire Hidden Heritage project has been made possible by the NSW Government through its Heritage Near Me program.
Any further information about local World War I Honor Rolls, locally issued ‘farewell’ gifts, etc. or their associated histories will be GREATLY welcomed and will be added to the above library of information.
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References and bibliography:
Australian Native Plants Society (Australia), (2016): Macrozamia communis. http://anpsa.org.au/m-comm.html
Canberra Times, 1990 ‘Riddle of the Burrawang’, Wednesday 11 April 1990, page 24.
Coastal Custodians, 2005 Volume 2 Issue 8, May 2005. Last accessed 7 March 2019 from: https://www.environment.nsw.gov.au/resources/comanagement/CoastalCustodiansVol2Is8.pdf
Cycad, plant order: Encyclopaedia Britannica. https://www.britannica.com/plant/cycad
Irene Terry, "Thrips and Weevils as Dual, Specialist Pollinators of the Australian Cycad Macrozamia communis (Zamiaceae)," International Journal of Plant Sciences 162, no. 6 (November 2001): 1293-1305.
Knut J. Norstoq: Cycadophyte. Encyclopaedia Britannica
Macrozamia, Plant genus: Encyclopaedia Britannica (Eds) https://www.britannica.com/plant/Macrozamia
Plantnet: Macrozamia communis from L.A.S. Johnson, Proc. Linn. Soc. New South Wales 64(1): 98 (1959). http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/cycadpg?taxname=Macrozamia+communis
Robert Ornduff (1989): 'Size distribution and coning behaviour of the Australian cycad Lepidozamia peroffskyana' Austral Ecology, Volume 14, Issue 2, Pages 241 - 245
T. Delevoryas: Gymnosperm, Plant. Encyclopaedia Britannica https://www.britannica.com/plant/gymnosperm#ref1216734