metrosideros polymorpha

Metrosideros polymorpha is relatively slow growing and may occur as a tall tree or a prostrate shrub, and everything in between. It can grow up to {{convert|30|m|ft|abbr=on}} in height. The trunk varies in form. In some trees, it is straight and smooth; in others, it is twisted and prominently fluted.{{cn|date=February 2025}}

Flowers are usually bright to medium red but orange-red, salmon, pink, yellow, or orange forms are also found. The flowers appear in clusters on the terminal ends of the branches. Masses of stamens extend from the flower and give the blossoms their characteristic pom-pom shape. The stomata of the leaves are able to close up in the presence of harmful gases, which gives it an advantage over many non-native trees.{{cite web |title=Trees |url=https://www.nps.gov/havo/learn/nature/trees.htm |access-date=26 January 2021 |website=Hawai'i Volcanoes National Park |publisher=National Park Service}}

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|Lehua blossoms hawaii 01.jpg|Lehua blossoms

|Metrosideros polymorpha (5113316760).jpg|Yellow flower variant

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There are about 50 species in the genus Metrosideros in Southeast Asia and the Pacific and as well one species in South Africa. The Hawaiian Islands are home to five species of Metrosideros that are endemic to the islands, meaning they are found nowhere else in the world. These are: Metrosideros polymorpha, M. macropus, M. rugosa, M. tremuloides, and M. waialealae. The species are readily distinguished from one another by the characteristics of their leaves.

Metrosideros kermadecensis, from the Kermadec Islands north of New Zealand, has recently become naturalized on Maui and may become a pest species. Several cultivars of M. excelsa, the pōhutukawa tree of New Zealand, have been sometimes planted as ornamentals in Hawai{{okina}}i but are not reported to have naturalized. Metrosideros polymorpha was originally classified as a variety of M. collina, native to Rarotonga, Tahiti, and other islands of Polynesia, but now is generally accepted as a distinct Hawaiian endemic species.{{cn|date=February 2025}}

File:Chlorodrepanis virens wilsoni 171723839.jpg drinking nectar]]

It is a common misconception that the word {{okina}}ōhi{{okina}}a is used to refer to the tree and that the word lehua refers only to its flowers. The Hawaiian Dictionary{{cite dictionary |year=1986 |title=lehua |dictionary=The Hawaiian Dictionary |page=199 |author2=Elbert |author1=Pukui}} describes lehua with these words:

: The flower of the {{okina}}ōhi{{okina}}a tree ... also the tree itself. {{grey|[emphasis added]}}

Thus endorsing the common practice of referring to Metrosideros polymorpha as a lehua tree, or as an {{okina}}ōhi{{okina}}a lehua, or simply an {{okina}}ōhi{{okina}}a.

The genus name Metrosideros is derived from the Greek words metra, meaning 'heartwood', and sideron, meaning 'iron', and refers to the hard wood of the trees in this genus. The specific epithet polymorpha, meaning 'many forms', is very appropriate, since individuals of this species exhibit many different morphologies and inhabit a broad range of ecological situations. The Hawaiian language word {{okina}}ōhi{{okina}}a is thought to have been derived from the ancestral Proto-Oceanic word, *kafika.{{Cite web |title=Pollex Online |url=https://pollex.shh.mpg.de/ |access-date=2019-04-12 |website=pollex.shh.mpg.de}} Throughout Oceania, there are many similar-sounding words that were also derived from the same ancestral protoform and, in most cases, they are names for the "mountain apple", or "Malay apple" tree, Syzygium malaccense. In the Hawaiian Islands, however, the word {{okina}}ōhi{{okina}}a is not only used to refer to Syzygium malaccense, but also to other species of Syzygium and Metrosideros that occur there.

The derivation of the word lehua is more obscure, and while there are many opinions regarding its origin, there has been, to date, no historical linguistic study of the word to provide convincing evidence for any particular etymology.{{Citation needed|reason=Statements about absence of evidence need citations too|date=December 2021}}

Metrosideros polymorpha is the most common native tree in the Hawaiian Islands, tolerating a wide range of soil conditions, temperature, and rainfall. It grows from sea level right up to the tree line at elevations of {{convert|2500|m|ft|abbr=on}} and is commonly found in moist and dry forests, high shrublands, and is a colonizer of recent lava flows. Dominant in cloud forests above {{convert|400|m|ft|abbr=on}}, the tree is also common in seasonally wet forests, where it may be dominant or form mixtures with the native Acacia koa.{{cn|date=February 2025}}

Preferred soils are acidic to neutral (pH 3.6–7.4) and either a Histosol, Mollisol, Podsol, Oxisol, Ultisol, or Alfisol. Rainfall of {{convert|1000|–|3000|mm|in|abbr=on}} per year is favored, but {{okina}}ōhi{{okina}}a can grow in dry forests that receive as little as {{convert|400|mm|in|abbr=on}} or bogs that get more than {{convert|10000|mm|in|abbr=on}} of rain.{{cite report |first1=J.B. |last1=Friday |first2=Darrell A. |last2=Herbert |date=April 2006 |title=Metrosideros polymorpha (ʻōhiʻa lehua) |publisher=The Traditional Tree Initiative |url=http://www.agroforestry.net/tti/Metrosideros-ohia.pdf}}

On moist, deep soils, {{okina}}ōhi{{okina}}a grows to {{convert|20|–|25|m|ft|abbr=on}} high. Trees growing in forests often have stilt roots, having germinated on logs or the stems of fallen hāpu{{okina}}u (Cibotium tree ferns), which have long decayed away when the tree has reached maturity. Some trees have fibrous aerial roots to gather moisture. At high elevations, and in areas with poor soils or little rainfall, shrub forms are the norm.{{cn|date=February 2025}}

File:Kalapana May 2009.jpg thirty-year-old pahoehoe flows from Kīlauea at Kalapana, Hawaii.]]

Metrosideros polymorpha forests in Hawai{{okina}}i have been invaded by myriad alien species. In the wet forests these include the strawberry guava (Psidium cattleyanum), albizia (Falcataria falcata), and "purple plague" (Miconia calvescens). In drier areas, problematic invaders include faya tree (Myrica faya) and Christmasberry (Schinus terebinthifolia). Alien grasses such as meadow ricegrass (Microlaena stipoides) may form an understory that prevents or inhibits natural regeneration of the forests. In drier areas, M. polymorpha has to compete with silk oak (Grevillea robusta) and fountain grass (Cenchrus setaceus).{{cn|date=February 2025}}

{{Main|Rapid ʻŌhiʻa Death}}

File:Lehua flower, Alaka'i Swamp Trail, Kauaʻi.jpg in Kaua'i]]

More recently, a strain of fungus initially identified as Ceratocystis fimbriata has attacked the ʻōhiʻa forests of the Big Island, causing rapid ʻōhiʻa death. The disease gets this name because healthy trees appear to die within a few days to a few weeks.{{cite web |title=Rapid ʻōhiʻa death |url=https://cms.ctahr.hawaii.edu/rod/ |access-date=5 March 2019 |website=College of Tropical Agriculture and Human Resources |publisher=University of Hawaii}} While {{okina}}ōhi{{okina}}a itself remains extremely abundant, some species that depend on it such as the ʻAkekeʻe (Loxops caeruleirostris) and longhorn beetles in the genus Plagithmysus have become endangered due to forest areas shrinking.{{cn|date=February 2025}}

In April 2018, the cause of rapid ʻōhiʻa death was identified as two species of Ceratocystis previously unknown to science: C. huliohia and C. lukuohia.{{cite news |date=2018-04-17 |title=Two new species of fungi that kill ʻōhiʻa trees get Hawaiian names |url=https://www.hawaii.edu/news/2018/04/16/ohia-killing-fungi-get-hawaiian-names/ |access-date=2018-05-14 |website=University of Hawaiʻi System News |lang=en-US}} By May 2018, infected ʻōhiʻa trees were found on the island of Kauai, prompting requests that members of the public limit transportation of ʻōhiʻa products within the island.{{cite news |date=2018-05-11 |title=ʻOhiʻa fungus found on Kauai |url=http://www.staradvertiser.com/2018/05/11/breaking-news/ohia-fungus-found-on-kauai/ |access-date=2018-05-14 |newspaper=Honolulu Star-Advertiser |department=Breaking news |lang=en-US}}

In 2022, to assist in slowing, and hopefully ending, Rapid ʻōhiʻa Death, the ʻōhiʻa became the state tree of Hawaii thanks to a bill signed into law by Governor David Ige.

The reddish brown heartwood of M. polymorpha is very hard, fine textured, and has a specific gravity of 0.7 .{{cite report |last=Allen |first=James A. |year=2003 |title=Metrosideros polymorpha Gaudich |publisher=Reforestation, Nurseries and Genetics Resources |url=http://www.rngr.net/publications/ttsm/species/PDF.2004-03-15.2731/at_download/file |url-status=live |access-date=2013-02-11 |format=PDF |archive-url=https://web.archive.org/web/20120519010409/http://www.rngr.net/publications/ttsm/species/PDF.2004-03-15.2731/at_download/file |archive-date=2012-05-19}} In native Hawaiian society, it is used in house and heiau construction, as well as to make papa ku{{okina}}i {{okina}}ai (poi boards), weapons, tool handles, hohoa (round kapa beaters), and ki{{okina}}i (statues and idols).{{cite report |first1=A.C. |last1=Medeiros |first2=C.F. |last2=Davenport |first3=C.G. |last3=Chimera |year=1998 |title=Auwahi: Ethnobotany of a Hawaiian dryland forest |publisher=Cooperative National Park Resources Studies Unit, University of Hawaiʻi at Mānoa |url=http://www.hear.org/naturalareas/auwahi/ethnobotany_of_auwahi.pdf}} Although the trunk of {{okina}}ōhi{{okina}}a is not used to make the ka{{okina}}ele (hull) of wa{{okina}}a (outrigger canoes), it was used for their nohona wa{{okina}}a (seats), pale (gunwales), and pola (decking). Wae (spreaders) were made from the curved stilt roots of {{okina}}ōhi{{okina}}a. Pā (fencing) was made from the wood due to its availability; kauila (Colubrina oppositifolia or Alphitonia ponderosa), more durable woods when in contact with soil, was rarer. As the wood burns hot and cleanly, it is excellent wahie (firewood). The lehua (flowers) and liko lehua (leaf buds) are used in making lei. The flowers were used medicinally to treat pain experienced during childbirth.{{cite web |title=Ohia lehua, lehua, ohia |website=Hawaiian Ethnobotany Online Database |publisher=Bernice P. Bishop Museum |url=http://data.bishopmuseum.org/ethnobotanydb/ethnobotany.php?b=d&ID=ohia_lehua |access-date=2009-02-23}}

{{okina}}Ōhi{{okina}}a lehua is one of the few honey plants that is native to the Hawaiian Islands.{{cite journal |first1=Kevin M. |last1=Roddy |first2=Lorna |last2=Arita-Tsutsumi |year=1997 |title=A history of honeybees in the Hawaiian Islands |journal=Journal of Hawaiian and Pacific Agriculture |volume=8 |page=61 |url=http://www.uhh.hawaii.edu/academics/cafnrm/research/documents/J_Haw_5_003.pdf}}

In Hawaiian mythology, {{okina}}Ōhi{{okina}}a and Lehua were two young lovers. The volcano goddess Pele fell in love with the handsome {{okina}}Ōhi{{okina}}a and approached him, but he turned down her advances. In a fit of jealousy, Pele transformed {{okina}}Ōhi{{okina}}a into a tree. Lehua was devastated by this transformation and out of pity the other gods turned her into a flower and placed her upon the {{okina}}ōhi{{okina}}a tree.{{cite web |title=Pele's Revenge: A Hawaii legend from Native American folklore |url=http://www.americanfolklore.net/folktales/ha2.html |access-date=2009-07-21 |archive-url=https://web.archive.org/web/20090609165100/http://americanfolklore.net/folktales/ha2.html |archive-date=2009-06-09 |url-status=dead }} Other versions say that Pele felt remorseful but was unable to reverse the change, so she turned Lehua into a flower herself.{{Cite web|url=http://www.goddessgift.com/goddess-myths/hawaiian-goddess-pele.htm|title=Pele: Goddess of the Volcano (Hawaii)|website=www.goddessgift.com|access-date=2019-04-12}} It is said that when a lehua flower is plucked from an {{okina}}ōhi{{okina}}a tree, the sky will fill with rain representing the separated lovers' tears.{{cite web |title=ʻŌhiʻa |url=https://www.nps.gov/articles/000/ohia.htm |website=Hawai'i Volcanoes National Park |publisher=U.S. National Park Service |access-date=26 January 2021}}

{{reflist}}

• {{cite report |author1=Medeiros, A.C. |author2=Davenport, C.F. |author3=Chimera, C.G. |date=2003-04-14 |publication-date=2009-10-28 |title=Auwahi: Ethnobotany of a Hawaiian Dryland Forest |url=http://www.hear.org/naturalareas/auwahi/ethnobotany_of_auwahi.pdf |series=Ethnobotany of Auwahi |access-date=3 January 2007}}
• {{cite book |author=Simpson, P. |year=2005 |title=Pōhutukawa & Rātā: New Zealand's iron-hearted trees |publisher=Te Papa Press}}
• {{cite report |author1=Starr, F. |author2=Starr, K. |author3=Loope, L.L. |date=27 July 2004 |section=New plant records from the Hawaiian Archipelago |editor1=Evenhuis, Neal L. |editor2=Eldredge, Lucius G. |title=Records of the Hawaii Biological Survey for 2004 – Part 2 |series=Bishop Museum Occasional Papers |volume=79 |pages=20–30 |publisher=Bishop Museum Press |place=Honolulu, HI}}
• {{cite report |title=Metrosideros polymorpha (ʻōhiʻa lehua) |series=Species Profiles for Pacific Island Agroforestry |date=April 2006 |id=version 3.2 |url=http://www.agroforestry.net/tti/Metrosideros-ohia.pdf |access-date=1 January 2007}}

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polymorpha

Category:Endemic flora of Hawaii

Category:Trees of Hawaii

Category:Biota of Hawaii (island)

Category:Biota of Kauai

Category:Biota of Lanai

Category:Biota of Maui

Category:Biota of Molokai

Category:Biota of Oahu

Category:Flora without expected TNC conservation status