GOING NATIVE : Now Showing

Christmas Best : Northern rata, Metrosideros robusta. Picture: NEIL PRICE.

Robyn Smith, of Otari Wilton’s Bush, says we should look to the rata, not to the pohutukawa, as Wellington’s Christmas tree.

CHRISTMAS in New Zealand is associated with pohutukawa and the Wellington region has a healthy number flowing well this season. Pohutukawa so not occur naturally in Wellington – only growing as far south as north Taranaki and Poverty Bay – but they are such beautiful trees, it is no wonder that they were taken to many other parts of the country. What really should be celebrated as the Wellington Christmas tree is its cousin, the northern rata, Metrosideros robusta. This tree also has magnificent red flowers, though of a different hue to pohutukawa, and also flowers around Christmas.

Rata can grow from the ground up in open sites into a small tree. However, it usually starts life perched high in the top of a tree, when a tiny wind borne seed lodges in the bark or trunk of a rimu or another conifer.

After germination, it forms tuberous-looking roots which store water and, eventually, one or two slender roots grow down to the ground where they thicken. More roots are sent to the ground and, by the time the supporting tree dies, all these roots join to form a pseudotrunk, which can measure two metres in diameter.

Rata has previously been called the “strangling rata” because it was thought that its roots killed the supporting. The view now is that the supporting tree is usually already mature when the rata begins its life, as the seed requires high levels of light to germinate and therefore the supporting tree needs to be up above the canopy trees.

It’s though that, possibly, the crown of the rata shades out that of the supporting tree and the competition for water and nutrients by the roots may hasten its death.

The resulting rata tree is very tall, up to 30 metres, with a broad canopy of branches. The flowers, which are produced on the ends of branchlets, provide nectar and pollen for many native insects, lizards, bats and birds.

Formerly abundant in lowland forests of the North Island and northern South Island, rata, like the pohutukawa, has suffered from browsing by possums. However, regular possum control by the Department of Conservation and regional and district councils has improved its survival prospects. Another local threat to rata is from pohutukawa, as the two species can cross pollinate to produce new plants that are neither one nor the other. This could mean over time, the rata will be displaced by these hybrids. To counter this, Project Crimson, a charitable conservation trust, was set up to help save rata and pohutukawa. Its vision is to “enable pohutukawa and rata to flourish again in their natural habitat as icons of all New Zealanders”.

Otari-Wilton’s Bush has 15 mature rata and this, autumn, seed will be collected and tested to determine whether there has been any genetic contamination from local pohutukawa. If pure, the seed will be used for restoration plantings throughout the Wellington city.

The Cockayne lookout at Otari-Wilton’s Bush is a great place to see one of these magnificent trees and the huge trunks can be seen from the Nature Trail. For the less adventurous, a large specimen is easily accessed in the Wild Garden. This tree has recently had a board-walk built around its roots to protect them.