Northern rātā (Metrosideros robusta), is a huge forest tree endemic to New Zealand. It grows up to 25 m. or more tall, and usually begins its life as a hemi-epiphyte high in the branches of a mature forest tree; over centuries the young tree sends descending and girdling roots down and around the trunk of its host, eventually forming a massive, frequently hollow pseudotrunk composed of fused roots. In disturbed ground, or where there are gaps in the forest cover, Northern rātā will grow on the ground with a normal but short trunk. Image File history File links No higher resolution available. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... Magnoliopsida is the botanical name for a class: this name is formed by replacing the termination -aceae in the name Magnoliaceae by the termination -opsida (Art 16 of the ICBN). ... Families See text. ... Genera 130; see list The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. ... Metrosideros is a genus of tree native to the islands of the Pacific Ocean, including the Bonin Islands, Polynesia, and Melanesia. ... This article does not cite any references or sources. ... Portait of Allan Cunningham Allan Cunningham (July 13, 1791 – June 27, 1839) was an English botanist and explorer. ...

Distribution

The leaves of Northern rātā have a distinct notch at the tip

Northern rātā is found in the North Island from Te Paki in the north to Wellington in the south. Formerly widespread, it is now uncommon over large parts of its former range, and is no longer found in Hawkes Bay. In the South Island, Northern rātā is common from Nelson to Greymouth and Hokitika. It reaches its southern limit near Lake Mahinapua. The natural habitat is forest along the coasts and in the lowlands. In some parts of its range Northern rātā occurs in montane forest. Formerly, with rimu (Dacrydium cupressinum) it was a dominant tree in a forest type known as rimu/rātā forest. North Island The North Island is one of the two main islands of New Zealand, the other being the South Island. ... For other uses, see Wellington (disambiguation). ... Hawkes Bay is a region of New Zealand. ... The South Island The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. ... Nelson may refer to: [edit] People with the Given Name Nelson Nelson Mandela, South African politician and activist Nelson Muntz, fictional cartoon character on The Simpsons Nelson Piquet, Brazilian racing driver Nelson Rockefeller, American politician Nelson Sale Kilifa, Solomon Islands footballer [edit] Places Nelson, British Columbia, Canada Nelson, Georgia, USA... Greymouth is the largest town in the West Coast region on the South Island of New Zealand, and the seat of the Grey District Council. ... Hokitika is a township on the West Coast of New Zealand, 38 kilometres south of Greymouth, and close to the mouth of the Hokitika River. ... Binomial name Dacrydium cupressinum Sol. ...

Description

A forest scene from 19th century New Zealand showing the descending roots of a Northern rātā linked together by girdling roots, all surrounding a dead and decaying host tree

Northern rātā is a massive tree, easily distinguished from other Metrosideros species by its small, leathery, dark green leaves which are 25-50mm long by 15-25mm wide, and have a distinct notch at the tip. Young growth is generally pink and covered in fine rust-coloured hairs that are gradually shed as the foliage ages but tends to persist at the midrib and in the vicinity of the leaf base. The flowers, borne in sprays on the tips of branches, are a mass of dark scarlet stamens. Flowering peaks between November and January, and seeds take a year or slightly more to ripen. The bark is usually brown or grey-brown and rather corky and provides an ideal stratum for the roots of epiphytic plants such as Astelia species and Freycinetia banksii (kiekie). The wood is reddish brown, and the manner of its growth results in a twisted grain.

Hemi-epiphytic growth habit

Northern rātā often begins life as hemi-epiphyte, and the resultant tree has a hollow trunk up to 4 m in diameter made up of interlocking roots which enclose the space left by the former host tree. In former times, the tree was described as a 'strangler', however it may be that rātā can only establish in trees that are already in decline. The host tree of epiphytic Northern rātā is usually rimu. Northern rātā usually occurs in hardwood, podocarp, and southern beech forests. It is often associated with such species as rewarewa, tawa, hīnau, kānuka, kahikatea, kāmahi, kohekohe, pukatea and māhoe. Binomial name Dacrydium cupressinum Sol. ... Species Nothofagus alpina - Rauli Beech Nothofagus antarctica - Antarctic Beech Nothofagus betuloides - Magellanes Beech Nothofagus cunninghamii - Myrtle Beech Nothofagus dombeyi - Coigüe Beech Nothofagus fusca - Red Beech Nothofagus gunnii - Tanglefoot Beech Nothofagus menziesii - Silver Beech Nothofagus moorei - Negrohead Beech Nothofagus obliqua - Roble Beech Nothofagus pumilio - Lenga Beech Nothofagus solanderi - Black Beech... Binomial name R. Br. ... Binomial name Beilschmiedia tawa The Tawa tree (Beilschmiedia tawa) is a New Zealand broadleaf tree common in coastal areas in the central parts of the country. ... Binomial name Dacrycarpus dacrydioides (A.Rich. ...

Conservation

The greatest threat to Northern rata is browsing by possums (Trichosurus vulpecula) which cause severe damage by eating the leaves, buds, flowers and young shoots of the tree. In severe cases this can lead to the death of the tree within two years. In some districts, this has resulted in the local loss of the species. The situation of the species has been improved through the efforts of Project Crimson. Hybridisation with pōhutukawa is another threat to the survival of Northern rātā. Pōhutukawa has naturalised in areas south of its natural range, and poses a problem in localities where the Northern or Southern rātā species are present. Other threats include cutting for firewood, and forest clearance for roading or construction. Binomial name Metrosideros excelsa Gaertn. ...

Cultivation

Northern rātā may be propogated readily from fresh seed. Viability of the seed drops quickly after a few weeks or if it is allowed to dry out. Cuttings do not strike readily, although better results are obtained from using water shoots.

See also

• Southern rātā
• Pōhutukawa
• Bartlett's rātā
• Scarlet rātā vine

Binomial name J.W.Dawson Bartletts rātā (Metrosideros bartlettii), or the Cape Reinga white rātā, is one of twelve Metrosideros species endemic to New Zealand and is notable for its extreme rarity and its white flowers, somewhat uncommon in that genus of red-flowered trees and plants. ...

External links

• Project Crimson

References

• Salmon, J.T., 1986. The Native Trees of New Zealand. Wellington: Heinneman Reed.
• Simpson, P., 2005. Pōhutukawa & Rātā: New Zealand's Iron-Hearted Trees. Wellington: Te Papa Press.
• Metrosideros robusta. Flora of New Zealand. Retrieved on 2007-06-09.
• Metrosideros robusta. New Zealand Plant Conservation Network. Retrieved on 2007-06-08.
• Northern Rata Fact Sheet. Project Crimson. Retrieved on 2007-06-09.
• Northern Rata Metrosideros robusta (fact sheet). Department of Conservation Te Papa Atawhai. Retrieved on 2007-06-18.
• Knightbridge, P.I.; and J. Ogden (1998). Establishment patterns and host tree preferences of the emergent hemi-epiphytic tree Metrosideros robusta in northern New Zealand. New Zealand Journal of Botany, 1998, Vol. 36: 203–212. Retrieved on 2007-06-13.