Metrosideros robusta, the northern rātā, is a forest tree endemic to New Zealand. It grows up to 25 metres (82 ft) or taller, and usually begins its life as a hemiepiphyte 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.
Northern rātā
A northern rātā towers above the forest at Kaitoke Regional Park, Wellington.
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 apparently absent from all but the south-east of Hawkes Bay. In the South Island, northern rātā is common from Nelson to Greymouth and Hokitika. It reaches its southern limit near Lake Mahinapua at 42°4′ South latitude. 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.
Description
The leaves of northern rātā have a distinct notch at the tip.
Northern rātā is a massive tree, easily distinguished from other Metrosideros species by its small, leathery, dark green leaves that 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 tend 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 that enclose the space left by the former host tree.
Rātā flowers at Mt Maungatautari
The host tree of epiphytic northern rātā is usually rimu. 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. 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.
Conservation
The greatest threat to northern rata is browsing by introduced 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.
Cultivation
Northern rātā may be propagated 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, but better results can be obtained from using water shoots.
At least three cultivars of northern rātā have been released.[1] There are also known cultivars of hybrids between northern rātā and pōhutukawa (known as Metrosideros ×sub-tomentosa), and between northern rātā and southern rātā.[2] Known cultivars include:
Variegated leaves with a characteristic twist on the leaves. Also marketed as M. robusta ‘Tane’s Gold’ by Duncan & Davies in 1996 and M. robusta ‘Twistie’.
^ abc"Metrosideros in cultivation: Rātā and other species" (PDF). New Zealand Garden Journal. 13 (2): 11. 2010.
^ abcd"Metrosideros in cultivation: Pōhutukawa" (PDF). New Zealand Garden Journal. 13 (1): 10–22. 2010. Retrieved 2015-05-25.
^. Vibrant Earth. Vibrant Earth. Archived from the original on 23 January 2015. Retrieved 16 June 2015.
^. Vibrant Earth. Vibrant Earth. Archived from the original on 23 January 2015. Retrieved 16 June 2015.
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 2007-06-09.
"Metrosideros robusta". New Zealand Plant Conservation Network. Retrieved 2010-10-02.
(PDF). Project Crimson. Archived from the original (PDF) on 2007-06-14. Retrieved 2007-06-09.
"Northern Rata Metrosideros robusta (fact sheet)" (PDF). Department of Conservation Te Papa Atawhai. Retrieved 2007-06-18.
Knightbridge, P.I.; J. Ogden (1998). "Establishment patterns and host tree preferences of the emergent hemi-epiphytic tree Metrosideros robusta in northern New Zealand" (PDF). New Zealand Journal of Botany, 1998, Vol. 36: 203–212. Retrieved 2010-10-07.[permanent dead link]
January 29, 2023
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This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations June 2010 Learn how and when to remove this template message Metrosideros robusta the northern rata is a forest tree endemic to New Zealand It grows up to 25 metres 82 ft or taller and usually begins its life as a hemiepiphyte 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 rata will grow on the ground with a normal but short trunk Northern rataA northern rata towers above the forest at Kaitoke Regional Park Wellington Scientific classificationKingdom PlantaeClade TracheophytesClade AngiospermsClade EudicotsClade RosidsOrder MyrtalesFamily MyrtaceaeGenus MetrosiderosSpecies M robustaBinomial nameMetrosideros robustaA Cunn Contents 1 Distribution 2 Description 3 Hemi epiphytic growth habit 4 Conservation 5 Cultivation 6 See also 7 ReferencesDistribution EditNorthern rata 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 apparently absent from all but the south east of Hawkes Bay In the South Island northern rata is common from Nelson to Greymouth and Hokitika It reaches its southern limit near Lake Mahinapua at 42 4 South latitude The natural habitat is forest along the coasts and in the lowlands In some parts of its range northern rata occurs in montane forest Formerly with rimu Dacrydium cupressinum it was a dominant tree in a forest type known as rimu rata forest Description Edit The leaves of northern rata have a distinct notch at the tip Northern rata is a massive tree easily distinguished from other Metrosideros species by its small leathery dark green leaves that 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 tend 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 EditNorthern rata 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 that enclose the space left by the former host tree Rata flowers at Mt MaungatautariThe host tree of epiphytic northern rata is usually rimu In former times the tree was described as a strangler however it may be that rata can only establish in trees that are already in decline Northern rata usually occurs in hardwood podocarp and southern beech forests It is often associated with such species as rewarewa tawa hinau kanuka kahikatea kamahi kohekohe pukatea and mahoe Conservation EditThe greatest threat to northern rata is browsing by introduced 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 rata Pōhutukawa has naturalised in areas south of its natural range and poses a problem in localities where the northern or southern rata species are present Other threats include cutting for firewood and forest clearance for roading or construction Cultivation EditNorthern rata may be propagated 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 but better results can be obtained from using water shoots At least three cultivars of northern rata have been released 1 There are also known cultivars of hybrids between northern rata and pōhutukawa known as Metrosideros sub tomentosa and between northern rata and southern rata 2 Known cultivars include Cultivar name Year introduced Flower colour Introduced by NotesM robusta Kawa Copper 1 2001 Dull orange red Deane Keir Coppery red coloured new growth M robusta Krinkley 1 1992 Dull orange red Variegated leaves with a characteristic twist on the leaves Also marketed as M robusta Tane s Gold by Duncan amp Davies in 1996 and M robusta Twistie M robusta Rangitoto Island 3 Crimson Graeme Platt Sourced from Rangitoto Island M sub tomentosa Hauparapara 2 Late 1980s Dull orange red Graeme Platt Sourced from Hauparapara River in the Bay of Plenty M sub tomentosa Mistral 2 Deep scarlet Graeme Platt Sourced from east of Coromandel township on the Coromandel Peninsula Metrosideros Sentinel Flame 2 2007 Bright red 4 Graeme Platt Vibrant Earth nursery Sourced from either Great Barrier Island or North West Nelson Hybrid of northern rata and southern rata Hybrid of northern rata and pōhutukawaSee also Edit Wikimedia Commons has media related to Metrosideros robusta Metrosideros excelsa pōhutukawa Metrosideros umbellata southern rata Metrosideros bartlettii Bartlett s rata Metrosideros parkinsonii Parkinson s rataReferences Edit a b c Metrosideros in cultivation Rata and other species PDF New Zealand Garden Journal 13 2 11 2010 a b c d Metrosideros in cultivation Pōhutukawa PDF New Zealand Garden Journal 13 1 10 22 2010 Retrieved 2015 05 25 Metrosideros robusta Rangitoto Island Vibrant Earth Vibrant Earth Archived from the original on 23 January 2015 Retrieved 16 June 2015 Metrosideros umb x rob Sentinel Flame Vibrant Earth Vibrant Earth Archived from the original on 23 January 2015 Retrieved 16 June 2015 Salmon J T 1986 The Native Trees of New Zealand Wellington Heinneman Reed Simpson P 2005 Pōhutukawa amp Rata New Zealand s Iron Hearted Trees Wellington Te Papa Press Metrosideros robusta Flora of New Zealand Retrieved 2007 06 09 Metrosideros robusta New Zealand Plant Conservation Network Retrieved 2010 10 02 Northern Rata Fact Sheet PDF Project Crimson Archived from the original PDF on 2007 06 14 Retrieved 2007 06 09 Northern Rata Metrosideros robusta fact sheet PDF Department of Conservation Te Papa Atawhai Retrieved 2007 06 18 Knightbridge P I J Ogden 1998 Establishment patterns and host tree preferences of the emergent hemi epiphytic tree Metrosideros robusta in northern New Zealand PDF New Zealand Journal of Botany 1998 Vol 36 203 212 Retrieved 2010 10 07 permanent dead link Retrieved from https en wikipedia org w index php title Metrosideros robusta amp oldid 1125982032, wikipedia, wiki, book, books, library,
