Grey mangroves grow to a height of three to ten metres. It has light-grey bark made up of thin, stiff, brittle flakes. The leaves are thick, five to eight centimetres long, a bright, glossy green on top and white or grey and hairy underneath. As with other Avicennia species, it has aerial roots (pneumatophores); these grow to a height of about 20 centimetres, and a diameter of one centimetre. The flowers range from white to a golden yellow colour, are less than a centimetre across, and occur in clusters of three to five. The species produces a large fleshy seed, often germinating on the tree and falling as a seedling. The grey mangrove can experience stunted growth in water conditions that are too saline, but thrive to their full height in waters where both salt and fresh water are present.

In South Australia along the Barker Inlet and Port River, A. marina forests form a hatchery for much of the states fish and shellfish.

Grey mangrove is a highly variable tree, with a number of ecotypes, and forms closely resembling other species. It has been reported to tolerate extreme weather conditions, high winds, and various pests and diseases. It is a pioneer in muddy soil conditions with a PH value of 6.5 to 8, but is intolerant of shade. A number of botanists have proposed division of the species, but currently three subspecies are recognised:

• Avicennia marina subsp. australasica
• Avicennia marina subsp. eucalyptifolia
• Avicennia marina subsp. marina

Notes

References

• Boland, D. J. et al. (1984). Forest Trees of Australia (Fourth edition revised and enlarged). CSIRO Publishing, Collingwood, Victoria, Australia. ISBN 0-643-05423-5..
• Duke, N.C. (1991). "A Systematic Revision of the Mangrove Genus Avicennia (Avicenniaceae) in Australasia". Australian Systematic Botany 4 (2): 299–324.