Common Name: Burrawang

General Information

Macrozamia spiralis is a slow-growing, evergreen, palm-like plant usually with a subterranean stem but sometimes becoming emergent, occasionally with branches, growing up to a height of around 30cm and and 8 - 20cm in diameter; this is topped by a crown of around 2 - 17, erect to spreading large leaves each around 60 - 100cm long[]
The plant was commonly harvested from the wild as a food source by native Aborigines in Australia, though it is little used at present because of the potential for poisoning. The plant yields a high quantity of starch and has been considered as a biofuel[, it is also sometimes grown as an ornamental.
Macrozamia spiralis has suffered an estimated population decline greater than 50% over three generations.The plant is classified as 'Endangered' in the IUCN Red List of Threatened Species(2010)[].

Known Hazards

None known

Botanical References

Range

Australia - eastern New South Wales

Habitat

Scattered in sclerophyll forests on sandy or gravelly soils of low fertility[]. An understory plant of dry to semiwet open sclerophyll forest, usually in flat areas, on poor, sandy or gravelly soils[].

Properties

Conservation Status	Endangered
Edibility Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	1.00 m
Growth Rate	Slow
Pollinators	Insects
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Macrozamia spiralis is native to the warm temperate zone ofeastern Australia with hot summers and cold winters with frequent frosts. The mean annual rainfall is around 800mm, falling throughout the year[]
An almost universal requirement for cycads is a well-drained but moisture-retentive soil, and by far the best soils are sandy gravels and light loams which provide the required drainage and aeration necessary for good growth. Cycads will generally not grow well in clay soils unless those soils are heavily amended with sand and organic matter[]. A neutral soil (pH 7), is generally best for most species of cycads and allows the proper absorption of nutrients. A slightly acid soil is better for most cycads than a basic one[].
Cycad species can usually be transplanted easily even when quite large. The best time for moving them is just before the beginning of a new growing season, the roots being trimmed if they are damaged and perhaps some leaves being removed. New roots should develop quickly as the season progresses[].
Species in this genus form structures known as coralloid roots. These roots branch off from the taproot or secondary roots and are distinctive in that they grow laterally or upward, forming a nodular mass at the apex. These coralloid roots occur slightly below or slightly above the soil surface and generally contain cyanobacteria, also known as blue-green algae. These are able to fix atmospheric nitrogen and make it available as a nutrient to the plant. The ability to extract this important nutrient from the air explains how many cycad species are able to survive on almost sterile soils[].
A dioecious species, with individual plants producing either all male or all female cones. Therefore both male and female forms of the plant need to be grown if seed is required[]. On very rare occasions, usually when a plant has been under severe stress, it can change sex and produce either all female or all male cones[].

Edible Uses

Caution should be employed if using any part of this plant for food. All parts of the plant can contain toxins and can only be eaten if proper measures are taken to remove these toxins.

Seed - cooked. The kernels are one of the most important sources of food for the New South Wales Aborigines. Toxic when first harvested the seeds are roasted, then pounded into a mass, which is then placed for 2 - 3 weeks in running water in order to take out the bitter principle, after which it can be eaten[]. The seed is 25 - 30mm long and 19 - 25mm in diameter[].
An arrowroot of very good quality can be obtained from the seed[].
Fresh seeds contain around 30 - 40% starch, rising to around 65 - 70% when the seed is dried[].

The plant is of potential commercial importance as a source of starch from its stems. The pith of the stem is dried either in the sun or by heating in an oven, it is then shredded up and soaked in water for six hours. It is then shaken
up and filtered, the milky fluid being allowed to settle. The sediment is washed several times, dried slowly, and finely powdered, and is ready for use[].

An insipid, jelly-like gum that is wholesome and not unpalatable can be obtained from the plant[].

Medicinal

None known

Other Uses

The leaves and stems are covered with a dense layer of hairs. These can be harvested as a kind of 'Pulu', which is occasionally used as a stuffing material for mattresses and couches. It would seem tedious to collect, but if the fronds are cut and left lying exposed to sun and wind for a few days, the 'pulu' comes of it quite easily, and often can be found loose on the ground. It is plentiful enough in certain districts for children to collect it profitably[].

Probably more than any other Australian cycad, this species has been investigated and exploited commercially for the starch in its stem. The starch makes a high quality laundry starch and afhesives, and has been produced on a commercial basis in the past. It has also been considered as a source of starch for conversion into biofuel[].

A gum is exuded from the cones, stems and bases of the leaves, often as a result of insect or other damage.
Gums of the various species of Macrozamia are nearly identical in character. It occurs in flattened pieces resembling 'button lac', in scaly pieces that have been likened to unbleached and unpurified gelatin, and in tears. Placed in water, the gum begins to swell almost immediately. The absorption of water goes on for several days, by the end of which the gum has swollen to from 50 - 100 times its original size. It then has the appearance of a colourless, quivering jelly. This behavior is much like that of cherry or acacia gums to which Macrozamia gums are apparently quite similar[].
The gum of Macrozamia was suspected once of being responsible for the poisonous effects of these plants but has been exonerated[]

Propagation

Seeds - best sown as soon as they are ripe, though the seeds of many species will take a few months to finish maturing the embryo before they are ready to germinate. Sow the seeds in a tray in a freely-draining medium and place in moderate shade. Bottom heat at about 27°c will hasten seed germination dramatically. Young roots are quite brittle and once germination takes place, the root grows rapidly. It is important to pot up the seedlings at this time in order to give them enough root-space. Grow on the plants in pots until large enough to plant out[].