Story by Tony Silbery and Erin Kavanagh-Hall
Northern rātā is one of our most recognisable trees. In the scientific world, it is known as Metrosideros robusta – meaning “stout iron heart”, in a reference to its stature and the strength of its wood. In this part of the world, rātā, along with its cousin pōhutukawa, has nabbed the title of “New Zealand’s Christmas Tree” – with its brilliant red flowers, glossy dark green leaves and sheer size (up to 25 metres high), it cuts an imposing figure in the forest. And, looks pretty on the front of holiday greeting cards!
This rakau rangatira (chiefly tree) is a familiar site in Wairarapa. Spread throughout the Tararua and Remutaka Ranges and with significant outliers at Pūkaha and the Aorangi Ranges, rātā has recovered from the ravages of possums that destroyed many old trees – and is now able to provide shelter and sustenance to a variety of other species, both plant and animal. One such creature which frequents northern rātā is the tui: as is captured in the logo for Tui beer (brewed, of course, in Mangatainoka) perched on a rata twig. Two Wairarapa icons combined!
Northern rātā usually begins life as a hemi-epiphyte (a “strangler”, in less flattering terms). This is a plant or tree which grows on the surface of another, eventually sending roots downwards to make contact with the ground, later enclosing the host plant.
The process begins with the rātā seed, which is smaller than an eyelash – and, similar to pohutukawa seeds, is irritating to human touch, even being sold as itching powder some years back. Once the seedling drops, it rides an air current high in the forest canopy. With no food reserves to sustain it, the seed must land in exactly the right place – usually among mosses and other perching plants high in the crown of a mature rimu. This guarantees high light levels while the mosses retain a supply of water, essential for growth. The combination of these two species is so widespread that it has given its name to a specific forest type: rimu/rātā forest.
For the first many decades, even centuries, of its life, rātā has to be pretty self sufficient. With its entire root system perched 20 or more metres above the ground, the fledgling tree must gather much of its water from the mosses and gain fertiliser from a weak solution of diluted bird poo and dust washing past with the rain. Eventually, the rātā’s roots make their way down the host’s trunk and plug into the earth. The roots fuse with those of the host tree, which later dies, leaving the rātā standing alone atop its hollow root system.
When the rātā flowers, usually between November and February, it becomes a feasting ground for a number of critters – particularly native bird species such as bellbird, kaka and the aforementioned tui. It is also a nectar-filled magnet for native bees, who transfer pollen between trees and start the development of those tiny seeds. And so, the cycle begins again.
Rātā has great significance in Māori culture. According to legend, Tawhaki, a young Maori warrior, climbed one of the great trees to find heaven, seeking help to avenge his father’s death. He fell to earth and the crimson flowers are said to represent his blood. The rātā was also valued by Māori for its medicinal properties. A concoction made from rātā bark and water was used to heal ringworm and applied to open wounds. Crushed and boiled bark was applied to bruises and ingested for the common cold, leaves were chewed for toothache, and nectar consumed to soothe a sore throat.
Following European settlement, timber was used for bridges, ship’s timbers, houses and furniture. These days, rata is highly prized for firewood (arguably a miserable fate for such a magnificent tree!) and is popular with woodturners, thanks to its deep reddish brown tones and purplish heart wood.
Rātā faces several threats – grazing from possums, deforestation and, as a member of the myrtle family, the recent arrival of myrtle rust. However, numbers throughout the country remain steady, thanks in part to Project Crimson, a partnership Department of Conservation and Carter Holt Harvey set up to fight the decline of both pohutukawa and rata. Since the early 90s, Project Crimson has funded the planting of more than 70,000 new trees.
Originally published in the Wairarapa Journal
Related story: A great pairing: forty years of wine and conservation
Rātā in flower, Remutaka Forest Park (Rebecca Jamieson)
