Metrosideros excelsa


Metrosideros excelsa, with common names pohutukawa, New Zealand Christmas tree, New Zealand Christmas bush, and iron tree, is a coastal evergreen tree in the myrtle family, Myrtaceae, that produces a brilliant display of red flowers made up of a mass of stamens. The pohutukawa is one of twelve Metrosideros species endemic to New Zealand. Renowned for its vibrant colour and its ability to survive even perched on rocky, precarious cliffs, it has found an important place in New Zealand culture for its strength and beauty and is regarded as a chiefly tree by Māori. The blossom of the tree is called kahika.

Etymology

The generic name Metrosideros derives from the Ancient Greek metra or "heartwood" and sideron or "iron". The species name excelsa is from Latin excelsus, "highest, sublime". Pōhutukawa is a Māori word. Its closest equivalent in other Polynesian languages is the Cook Island Māori word po'utukava, referring to a coastal shrub with white berries, Sophora tomentosa. The -hutu- part of the word comes from *futu, the Polynesian name for the fish-poison tree, which has flowers similar to those of the pohutukawa.

Description

The pohutukawa grows up to high, with a spreading, dome-like form. It usually grows as a multi-trunked spreading tree. Its trunks and branches are sometimes festooned with matted, fibrous aerial roots. The oblong, leathery leaves are covered in dense white hairs underneath.
The tree flowers from November to January with a peak in mid to late December, with brilliant crimson flowers covering the tree, hence the nickname New Zealand Christmas tree. There is variation between individual trees in the timing of flowering, and in the shade and brightness of the flowers. In isolated populations genetic drift has resulted in local variation: many of the trees growing around the Rotorua lakes produce pink-shaded flowers, and the yellow-flowered cultivar 'Aurea' descends from a pair discovered in 1940 on Mōtiti Island in the Bay of Plenty.

Uses

Pohutukawa wood is dense, strong and highly figured. Maori used it for beaters and other small, heavy items. It was frequently used in shipbuilding, since the naturally curvy shapes made strong knees.

Distribution

The natural range of the pohutukawa is the coastal regions of the North Island of New Zealand, north of a line stretching from New Plymouth to Gisborne, where it once formed a continuous coastal fringe. By the 1990s, pastoral farming and introduced pests had reduced pohutukawa forests by over 90%. It also occurs naturally on the shores of lakes in the Rotorua area and in Abel Tasman National Park at the top of South Island.
A giant pohutukawa at Te Araroa on the East Coast is reputed to be the largest in the country, with a height of 20 metres and a spread of. The tree is renowned as a cliff-dweller, able to maintain a hold in precarious, near-vertical situations. Like its Hawaiian relative the , the pohutukawa has shown itself to be efficient in the colonisation of lava plains – notably on Rangitoto, a volcanic island in the Hauraki Gulf.

Conservation

In New Zealand, the pohutukawa is under threat from browsing by the introduced common brushtail possum which strips the tree of its leaves. A charitable conservation trust, Project Crimson, has the aim of reversing the decline of pohutukawa and other Metrosideros species – its mission statement is "to enable pohutukawa and rata to flourish again in their natural habitat as icons in the hearts and minds of all New Zealanders".

Cultivation

The pohutukawa is popular in cultivation, and there are fine examples in most North Island coastal cities. Vigorous and easy to grow, the tree flourishes well south of its natural range, and has naturalised in the Wellington area and in the north of the South Island. It has also naturalised on Norfolk Island to the north. The pohutukawa has been introduced to other countries with mild-to-warm climates, including south-eastern Australia, where it is naturalising on coastal cliffs near Sydney. In coastal California, it is a popular street and lawn tree, but has caused concern in San Francisco where its root systems are blamed for destroying sewer lines and sidewalks. In parts of South Africa, the pohutukawa grows so well that it is regarded as an invasive species. The Spanish city of A Coruña has adopted the pohutukawa as a floral emblem.
At least 39 cultivars of pohutukawa have been released. Duncan & Davies nurseries were a leading force in the mid-20th century, while Graeme Platt has been responsible for 16 different cultivars so far, including a rare white-flowering tree. Known cultivars of pohutukawa include:
Cultivar nameYear IntroducedFlower ColourIntroduced byNotes
M. excelsa ‘Aurea’1947Greenish-yellowDuncan & DaviesSourced from Motiti Island.
M. excelsa ‘Blockhouse Bay’mid-1980sBright redGraeme PlattSourced from Blockhouse Bay, Auckland.
M. excelsa ‘Butterscotch’1993Fire RedDuncan & DaviesReddish stems and reddish-gold new leaves becoming butter-yellow and finally green with age. Sourced from M. excelsa ‘Sunglow'.
M. excelsa ‘Centennial’--Graeme PlattReverse-variegated cultivar, erect growth habit. Sourced from Auckland Domain centennial plantings.
M. excelsa ‘Christmas Cheer’-CrimsonBob BaylyConsistently flowering around Christmas time. Flowers in large clusters.
M. excelsa ‘Dalese’2010Orange-redLyndale NurseriesCompact, low-growing selection. Often incorrectly sold as M. tomentosa ‘Dalese’, especially in Australia.
M. excelsa ‘Fire Mountain’mid-1970sOrange-scarletFelix Jury / Duncan & DaviesVery bright flowers and spreading habit. Sourced from Waitara riverbank plantings.
M. excelsa ‘Firestone’1983Fire-redGraeme PlattBright flowers and sprawling form. Sourced from Mt Moehau, Coromandel Peninsula.
M. excelsa ‘Flame Crest’1991Orange-scarletCyril Watson & George Smith / Duncan & DaviesTall, erect form. Sourced from Kawaroa Park, New Plymouth.
M. excelsa ‘Gold Finger’1986Deep crimsonDuncan & DaviesReverse-variegated form with bright gold leaves.
M. excelsa ‘Golden Dawn’2003Melon PinkRobert HarrisonReverse-variegated cultivar from Australia. Grows to around 5 metres. Grew from M. excelsa ‘Pink Lady’ under cultivation. 10–20% chance of variegation reverting.
M. excelsa ‘Gold Nugget’2000-Jim Rumbal / Duncan & DaviesVariegated cultivar with fresh green margins and yellow centres.
M. excelsa ‘‘Hauraki’-RedGraeme PlattOutstanding sized flowers and tall, erect form. Sourced from Long Bay Regional Park, Auckland.
M. excelsa ‘Kopere’2007Orange-redGraeme PlattVibrant flowers and glossy green leaves. Sourced from Brooks Bay, near Awhitu Regional Park, Auckland.
M. excelsa ‘Lighthouse’1983CrimsonGraeme PlattEarly flowering. Sourced from Rangitoto Island.
M. excelsa ‘Manukau’1990Orange-redGraeme PlattWell-balanced flower heads that also bloom inside the canopy of the tree. Sourced from Manukau City shopping centre.
M. excelsa ‘Maori Princess’1970sRedIan McDowell / Duncan & DaviesOpen branched, upright tree. Sourced from Brougham Street, New Plymouth.
M. excelsa ‘Midas’1988RedWilliam RobertsonReverse-variegated cultivar from Australia, but slightly unstable
M. excelsa ‘Mini Christmas’-RedLow growing cultivar from Australia, grows to around 1m tall.
M. excelsa ‘Moon Maiden’1988Sulphur yellowDuncan & DaviesLight grey-green foliage. Sourced from M. excelsa ‘Aurea'.
M. excelsa ‘Mt Maunganui’1993RedLyndale NurseriesSourced from Pitau Road, Mount Maunganui. Source tree of significance to Ngāi Te Rangi iwi, where several Māori skeletons were found at its base.
M. excelsa ‘Octopussy’2004RedNaturally Native NZ Plants AucklandWeeping growth habit. Sometimes available as a standard.
M. excelsa ‘Ohope’-RedDuncan & DaviesVariegated form. Green leaves with cream margins.
M. excelsa ‘Parnell’early 1970sRedGraeme PlattVery large and widely spreading tree. Sourced from Parnell Rose Gardens, Auckland.
M. excelsa ‘Pink Lady’1988Melon PinkDuncan & DaviesSmall upright tree with compact flower heads.
M. excelsa ‘Plus Four’2002Bright RedGraeme PlattUpright growth habit. Sourced from Awhitu Golf Course, Auckland.
M. excelsa ‘Pouawa’--Graeme Platt / Rob BaylyLong-lasting flowers. Sourced from north of Gisborne.
M. excelsa ‘Rangitoto’mid-1980sDark RedTom Johnson / Dawn NurseriesUpright, smallish tree. Sourced from Te Atatū, Auckland from a plant originally sourced on Rangitoto Island.
M. excelsa ‘Royal Flame’1988Deep-crimsonJim Rumbal / Duncan & DaviesUpright tree, flowers have contrasting yellow anthers. Sourced from Waitara West Marine Park.
M. excelsa ‘Scarlet Pimpernel’1976ScarletFelix Jury / Duncan & DaviesSmall, compact growth. Suitable for containers & patios. Sourced from Princess Street, Waitara.
M. excelsa ‘Sunglow’1980-Duncan & DaviesVariegated with gold leaf margins. flowers and form. Thought to be sourced from Oswald Blumhardt, plant breeder in Whangarei.
M. excelsa ‘Tamaki’1985Orange-redGraeme PlattBright flowers. Sourced from Tamaki Drive, Auckland.
M. excelsa ‘Te Kaha’mid-1980sRed with orange hints.Graeme PlattMedium-sized bushy tree. Sourced from Te Kaha Hotel, Bay of Plenty.
M. excelsa ‘Titirangi’late-1980sScarletGraeme PlattErect tree with copious flowers. Sourced from Margan Ave, Auckland near the Titirangi Golf Course.
M. excelsa ‘Upper Hutt’---Reverse-variegated foliage. Sourced from public gardens in Upper Hutt.
M. excelsa ‘Variegata’-Red-Variegated leaves. Not to be confused with M. kermadecensis. 'Variegata'.
M. excelsa ‘Vibrance’1985Orange-redGraeme PlattFlowers have exceptionally long stamens. Sourced from Waiomu Bay, Coromandel Peninsula.
M. excelsa ‘Whakarewarewa’late-1980sVery dark redGraeme PlattSourced from Whakarewarewa, Rotorua.
M. excelsa ‘White Caps’2009WhiteGraeme PlattSourced from Piha Beach, Auckland.