Adiantum cunninghamii < Species index > Alectryon excelsus
This article was first published in the Tararua Tramper Volume 95, # 5, June 2023
June in the hills with Michele Dickson, Chris Horne
Agathis australis, Kauri,
Origin of the botanical names
‘Agathis’ is the Greek word meaning ‘a spool wound with thread’, referring to the likeness of the cone and cone scales of the plant to a ball of yarn; ‘australis’ is the Latin word meaning ‘southern’. The Agathis genus is a member of the Aracariaceae family, an ancient conifer family dating back to about 120 million years ago. Kauri is the only New Zealand member of this family, which is found mostly in the southern hemisphere and includes many timber trees of the genera Araucaria and Agathis. An introduction to conifers was outlined in the Tramper, February 2015.
Distribution and habitat
Kauri is endemic to New Zealand. It grows on Te Ika a Māui / North Island, from near Cape Reinga south to Kawhia in the West and near Te Puke in the East. Following severe logging, it is now found only in protected forests and reserves. It has been planted in many more southern locations where it thrives and has sometimes produced seedlings. In the north, it is best seen in Waipoua Forest in Northland / Te Tai Tokerau, Coromandel Peninsula, Waitakere Ranges Regional Park and Aotea / Great Barrier Island, growing mostly in lowland forest and hills where it forms dense canopies with particular associated species.
Growth habit
Kauri is a large, resiniferous forest tree 30–60 m tall with a trunk diameter up to 7 m, free of branches for at least half its height. Juvenile trees have a columnar growth form with some lower branches, which fall off later. The bark is bluish-grey with peeling large thick flakes with wavy edges. Leaves / needles are mostly alternate, leathery, parallel-veined and without stalks. Juvenile leaves are lanceolate, 50-100 mm long and often brown; adult leaves are linear-oblong, 30-40 mm long and green. Some trees have been estimated to be 4000 years old. Young kauri are called rickers. Kauri dieback has become a serious disease. It is caused by a microscopic soil-borne pathogen called Phytophthora agathidicida which infects the roots. Research and management to restrict its spread is carried out by several organisations including Victoria University.
Reproduction
Kauri is monoecious, having separate male and female cones on the same tree. Cones appear in spring and summer. Male cones are 20-50 mm long, stout, cylindrical and female cones are 50-75 mm in diameter and globose. Cone-scales on female cones are spirally arranged and bear ovules/seeds. The leathery to woody scales are widened above but then narrow toward the base, bearing one ovule/seed per scale. Seeds are released from cone scales when the cones scales open out from the cone or when cones fall and break. They are ovoid, compressed, with winged margins and ripen over two years.
Uses
The durable timber has been used for houses, buildings, boat-building, furniture, cabinetry, veneers, musical instruments and turned objects. Māori used the timber for waka / canoe-making, carvings and domestic objects. Swamp kauri preserved in swamps and bogs is used like new timber. Kauri gum from the tree trunks, both fossil and fresh, has been a valuable commercial commodity, especially for varnish-making. Burnt resin was used to attract tuna / eels and other fish. For dyes, Māori used soot from burning resin for tattooing and for black paint. Soot from burning timber mixed with shark oil was used for painting waka / canoes. For medicinal uses, gum scraped to powder has been applied with olive oil to burns and fresh gum resin has been used as a chewing gum.
Where can you find kauri planted locally?
In Ōtari-Wilton's Bush many kauri, some in a grove, have been planted, the first in 1929. Kauri St. in Waterloo, Lower Hutt, is lined with kauri.
Note: Kauri does not grow locally naturally.
In The Hills 2023-05 < Index chronological > In The Hills 2023-07