Macrozamia

Miq. (1842)

Common names

Burrawangs, Zamia-palms (Harden 1990).

Taxonomic notes

A genus of 41 species. I have some information on two species (discussed below) but for all species, see the descriptions provided by The World List of Cycads.

Description

"More or less palm-like dioecious plants with a usually unbranched stem forming a rather massive aerial trunk often >50 cm diam., or stem mainly subterranean, covered by the persistent leaf bases; all parts ± pubescent when young, glabrescent with age. Leaves few to numerous, simply pinnate but the pinnae sometimes dichotomously divided, the rachis straight or twisted; base of the petiole swollen, usually silky or tomentose. Pinnae numerous in mature plants, spreading or turned to one side, inserted near the edges of the rachis towards the upper side. Cones axillary, pedunculate; sporophylls terminated by upturned spines; spines usually largest towards apex of cone. Male cones ± cylindrical, often curved when old. Female cones ± ovoid, inner parts often bright pink; sporophylls with 2 ovules; sporophylls fall with attached seeds when ripe; seed with an outer fleshy brightly-coloured layer. "Note: juvenile plants may differ considerably from the adult forms in details of the leaves; in particular the pinnae are usually toothed at the ends and the petioles are long and slender" (Harden 1990).

Distribution and Ecology

Australia: Queensland, New South Wales, Northern Territory, and Western Australia. Subtropical and warm-temperate areas, usually on poor soils in sclerophyll communities (Harden 1990).

M. communis (photos at right) "grows in sclerophyll forest on sandy to loamy soils, often in dense stands; on the coast and adjacent ranges from the Macleay R. system to Bega, and the Goulburn R. district" (Harden 1990).

M. moorei (photos at right) occurs in NSW & Queensland, N f/Clarence R. valley, including the Carnarvon Range and Emerald, Springsure and Rolleston districts (Harden 1990, Jones 1993). In NSW, it occurs "[m]ostly in foothills of ranges in tall wet sclerophyll forest and margins of rainforest, generally on steep slopes" (Harden 1990); in Qld, occurs on low hills in dry sclerophyll forests and woodland, and in the valleys and escarpments of rocky gorges. Summer climate diurnal range 21-35°C, winter 6-23°C; severe frosts common. Annual rainfall 500 mm, with a summer maximum (Jones 1993).

Remarkable Specimens

M. dyeri (up to 6.5 m tall and 100 cm diameter) and M. moorei (up to 8 m tall and 80 cm diameter) are the largest species in the genus (Jones 1993).

M. moorei plants have grown to 2 m tall from seed in less than 100 years. Plants cone in about 50 years (Jones 1993). Since plants 8 m tall are known, extrapolation would suggest that ages may exceed 400 years.

Ethnobotany

Most parts of the plants are toxic. Various species are held responsible for poisoning livestock (Harden 1990). The seeds are poisonous, but the "Aborigines knew how to treat them to remove the poison, and so take advantage of the large amount of food provided by a single plant. One treatment was to cook the seed, break it up, and then soak it for up to three weeks in running water. In Western Australia, only the outer red part was eaten, after treatment by washing and burying" (ANBG 2001).

Observations

I found M. moorei to be common in and around Carnarvon National Park in Queensland (including the type locality).

Remarks

The earliest fossil Macrozamia are known from Oligocene sediments in Tasmania (Jones 1993).

M. moorei was described in 1881 from material collected on the Nogoa River near Springsure. This species typically occurs in large colonies in scenic rocky areas. Mature cones are exceptionally large and numerous. The female cone is the largest in the genus and up to 100 cones have been recorded on a single male plant. In cultivation, it is hardy, preferring full sun but tolerating heavy frost. Transplants readily (Jones 1993).

Citations

ANBG 2001. Australia National Botanical Garden, Aboriginal Trail page. http://osprey.erin.gov.au/anbg/aboriginal-trail.html, accessed 2001.06.11, now defunct.

Jones, David L. and Paul I. Forster. 1994. Seven new species of Macrozamia section Parazamia (Miq.) Miq. (Zamiaceae section Parazamia) from Queensland. Austrobaileya 4: 269-288. ABSTRACT: Seven new species of Macrozamia section Parazamia (Miq.) Miq. from south-east Queensland are described and illustrated. They are M. conferta, M. cranei, M. crassifolia, M. machinii, M. occidua, M. parcifolia, and M. viridis. All are restricted endemics allied to either M. plurinervia (L.A.S. Johnson) D.L. Jones or M. pauliguilielmi W. Hill & F. Muell. A key to the species of M. section Parazamia in Queensland is presented.

Miquel, F. A. W. 1842. Monographia Cycadearum 36, t. 4, 5.

See also