''Metrosideros'' is a genus of approximately 60

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s, shrubs, and

vine A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to such stems or runners themsel ...

s mostly found in the Pacific region in the family Myrtaceae. Most of the tree forms are small, but some are exceptionally large, the New Zealand species in particular. The name derives from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

''metra'' or "

heartwood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin t ...

" and ''sideron'' or "iron". Perhaps the best-known species are the

pōhutukawa ''Metrosideros excelsa'', commonly known as pōhutukawa ( mi, pōhutukawa), 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 o ...

(''M. excelsa''), northern (''M. robusta'') and southern rātā (''M. umbellata'') of New Zealand, and '' ōhia lehua'' (''M. polymorpha''), from the Hawaiian Islands.

Distribution

''Metrosideros'' is one of the most widely spread flowering plant genera in the Pacific. New Caledonia has 21 species of ''Metrosideros'',

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

has 12,

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

has seven and

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

has 5. The genus is present on most other high Pacific Islands, including

Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capit ...

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of no ...

, Fiji,

Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...

Cook islands ) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , lan ...

, French Polynesia,

Bonin Islands The Bonin Islands, also known as the , are an archipelago of over 30 subtropical and tropical islands, some directly south of Tokyo, Japan and northwest of Guam. The name "Bonin Islands" comes from the Japanese word ''bunin'' (an archaic read ...

and

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland P ...

, but absent from

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...

. The genus is also represented by one species in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, one in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

(Chile and Argentina), and one outlier in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

. ''Metrosideros'' seeds are very lightweight and easily dispersed by wind. The seeds can also survive freezing temperatures, and up to 30 days submerged in salt water and still germinate. which probably accounts for their wide distribution. They are often found as pioneer trees on lava flows and on mountain ridges. Despite the clear propensity towards long-distance dispersal, this genus does not occur in mainland Australia.Tarran, Myall, Peter G. Wilson, and Robert S. Hill. "Oldest record of Metrosideros (Myrtaceae): Fossil flowers, fruits, and leaves from Australia." American Journal of Botany 103.4 (2016): 754-768.

Fossil record

For some time it had been hypothesised that ''Metrosideros'' evolved in

, and dispersed from there throughout the Pacific. This was due to the long fossil record of ''Metrosideros'' in New Zealand coupled with the absence of any ''Metrosideros'' fossils on other

Gondwanan Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stage ...

landmasses. The oldest conclusive fossil evidence of ''Metrosideros'' in New Zealand is fossil fruits from the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

aged Manuherikia sediments of Central Otago. There is a fossil pollen record going back much further, but it has been shown that ''Metrosideros'' pollen is very similar morphologically to many other genera within the family Myrtaceae and as such, fossil pollen cannot be reliably used as an oldest record of the genus. The oldest conclusive record of ''Metrosideros'' are fossil fruits and flowers of '' Metrosideros leunigii'', an extinct species, from Oligocene aged sediments in Tasmania, Australia. This is very curious considering that ''Metrosideros'' is one of the most widely spread plants in the Pacific, and is not present in Australia today. These fossils may also point towards an Australian origin for the genus.

Cultivation

''Metrosideros'' are often cultivated for their showy flowers, as street trees or in home gardens. The flowers are generally red, but some cultivars have orange, yellow or white flowers. Some names listed in horticultural catalogues and other publications, such as ''M. villosa'' and ''M. vitiensis'', are actually the names of varieties or cultivars (usually of ''M. collina'') rather than valid scientific species. The

of New Zealand has several cultivars grown in Australia, Hawaii and

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

and it has been planted successfully in the north of

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

and on the

Scilly Isles The Isles of Scilly (; kw, Syllan, ', or ) is an archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, is the most southerly point in Britain, being over further south than the most southerly point of the ...

off the south-west coast of

Britain Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...

, but the species is considered an invasive pest in parts of South Africa and in the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

.Governo dos Açores: "Government invests in fight against invasive exotic species"
/ref> ''

Metrosideros kermadecensis ''Metrosideros kermadecensis'', with common names ''Kermadec pōhutukawa'' and New Zealand Christmas bush is an evergreen tree of the myrtle family which is endemic to the volcanic Kermadec Islands about 900 km north-east of New Zealand. ...

'' is recently naturalised in Hawaii, and has the potential to become a pest. In turn, various cultivars of ''M. collina'' and ''M. polymorpha'' are widely grown in New Zealand under various names. ''

Metrosideros umbellata ''Metrosideros umbellata'', the southern rātā, is a tree endemic to New Zealand. It grows up to or more tall with a trunk up to or more in diameter. It produces masses of red flowers in summer. Unlike its relative, northern rātā, this spe ...

'' occurs naturally south of mainland New Zealand in the

Auckland Islands The Auckland Islands (Māori: ''Motu Maha'' "Many islands" or ''Maungahuka'' "Snowy mountains") are an archipelago of New Zealand, lying south of the South Island. The main Auckland Island, occupying , is surrounded by smaller Adams Islan ...

at 50° South latitude, and is the hardiest member of the genus, and a few cultivated specimens are growing in

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

''Metrosideros'' species

Metrosideros bartlettii ''Metrosideros bartlettii'', also known as Bartlett's rātā, Cape Reinga white rātā or in Māori as rātā moehau, is one of twelve ''Metrosideros'' species endemic to New Zealand and is notable for its extreme rarity and its white flowers, s ...

'' - Bartlett's rātā * ''

Metrosideros carminea ''Metrosideros carminea'' (Carmine rātā, Crimson rātā or in Māori akakura) is a forest liane or vine that is endemic to New Zealand. It occurs in coastal and lowland forest from Te Paki in the north of the North Island south to Māhia Penins ...

'' - Carmine rātā * ''

Metrosideros colensoi ''Metrosideros colensoi'', the climbing rata or Colenso's rātā, is a forest liane or vine that is endemic to New Zealand. It is one of a number of New Zealand Metrosideros species which live out their lives as vines, unlike the northern rata ( ...

'' - Colenso's rātā * ''

Metrosideros diffusa ''Metrosideros diffusa'', the white rātā, climbing rātā or in Māori akakura, is a forest liane or vine endemic to New Zealand. It is one of a number of New Zealand ''Metrosideros'' species which live out their lives as vines, unlike the nort ...

'' - White rātā * ''

Metrosideros excelsa ''Metrosideros excelsa'', commonly known as pōhutukawa ( mi, pōhutukawa), 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 o ...

'' - Pōhutukawa * ''

Metrosideros fulgens ''Metrosideros fulgens'' (scarlet rātā, rātā vine or in Māori akatawhiwhi) is a forest liana or vine endemic to New Zealand. It occurs in coastal and lowland forest throughout the North Island, on the west coast of the South Island and on th ...

'' - Scarlet rātā * ''

'' - Kermadec pōhutukawa (Kermadec Islands) * ''

Metrosideros parkinsonii ''Metrosideros parkinsonii'', also known as Parkinson's rātā or shrubby rata, is a shrub or small tree endemic to New Zealand. The name commemorates Sydney Parkinson, Captain James Cook's botanical artist during his first voyage to New Zealan ...

'' - Parkinson's rātā * ''

Metrosideros perforata ''Metrosideros perforata'', also known as white rata, climbing rata, akatea or Akatorotoro, is one of twelve ''Metrosideros'' species endemic to New Zealand. It is one of three white flowering rātā vines (the others being large white rātā a ...

'' - Small white rātā * ''

Metrosideros robusta ''Metrosideros robusta'', the northern rātā, is a forest tree endemic to New Zealand. It grows up to 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 d ...

'' - Northern rātā * ''

'' - Southern rātā New Guinea * '' Metrosideros arfakensis'' * '' Metrosideros cordata'' * '' Metrosideros ovata'' * '' Metrosideros parallelinervis'' * '' Metrosideros ramiflora'' * '' Metrosideros regelii'' * '' Metrosideros whiteana'' Philippines * '' Metrosideros halconensis'' ;Hawaii * ''

Metrosideros macropus ''Metrosideros macropus'', the ''lehua mamo'' or ohi'a'', is a species of tree in the eucalyptus family, Myrtaceae. It is endemic to the island of Oahu in the Hawaiian Islands. It is closely related to the widespread and highly variable ''ōhia ...

'' - ''Lehua mamo'' (Oahu) * ''

Metrosideros polymorpha ''Metrosideros polymorpha'', the ''ōhia lehua'', is a species of flowering evergreen tree in the myrtle family, Myrtaceae, that is endemic to the six largest islands of Hawaii. It is a highly variable tree, being tall in favorable situations ...

'' - ''Ōhia lehua'' * '' Metrosideros rugosa'' - ''Lehua papa'' (Oahu) * '' Metrosideros tremuloides'' - ''Lehua āhihi'' (Oahu) * '' Metrosideros waialealae'' (Kauai, Molokai, and Maui) French Polynesia, Pitcairn and the Cook Islands * ''

Metrosideros collina ''Metrosideros collina'' is a species of flowering plant in the family Myrtaceae. It is native to French Polynesia and the Cook Islands. Taxonomy The species was first formally described by botanist Johann Reinhold Forster and his son Georg F ...

'' Fiji, Samoa and Vanuatu * '' Metrosideros gregoryi'' (Samoa) * '' Metrosideros ochrantha'' (Fiji) * '' Metrosideros tabwemasanaensis'' (Vanuatu) * '' Metrosideros vitiensis'' Solomon Islands * '' Metrosideros salomonensis'' * '' Metrosideros tetragyna'' Lord Howe Island * '' Metrosideros nervulosa'' - Mountain rose * '' Metrosideros sclerocarpa'' Ogasawara Islands * ''

Metrosideros boninensis ''Metrosideros boninensis'' is a species of flowering plant in the family Myrtaceae. It is endemic to the Bonin Islands archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection ...

References

External links