Metrosideros polymorpha
Encyclopedia
The ōhia lehua is a species of flowering
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

 evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

 tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 in the myrtle family, Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...

, that is endemic to the six largest islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...

 of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

. It is a highly variable tree, being 20–25 m (65.6–82 ft) tall in favorable situations, and much smaller when growing in boggy soils or on basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

. It produces a brilliant display of flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s, made up of a mass of stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...

s, which can range from fiery red to yellow. Many native Hawaiian traditions refer to the tree and the forests it forms as sacred to Pele, the volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 goddess, and to Laka
Laka
In Hawaiian mythology, Laka is the name of a popular hero from Polynesian mythology....

, the goddess of hula
Hula
Hula is a dance form accompanied by chant or song . It was developed in the Hawaiian Islands by the Polynesians who originally settled there. The hula dramatizes or portrays the words of the oli or mele in a visual dance form....

.

Distribution

Metrosideros polymorpha is the most common native tree in the Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...

, tolerating a wide range of soil conditions, temperature, and rainfall. It grows from sea level right up to the tree line at elevations of 2500 m (8,202.1 ft) and is commonly found in moist and dry forests
Hawaiian tropical dry forests
The Hawaiian tropical dry forests are a tropical dry broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of on the leeward side of the main islands and the summits of Niihau and Kahoolawe. These forests are either seasonal or sclerophyllous. Annual rainfall is less than and...

, high shrublands
Hawaiian tropical high shrublands
The Hawaiian tropical high shrublands are a tropical savanna ecoregion in the Hawaiian Islands. They cover an area of on the upper slopes of the volcanoes Mauna Kea, Mauna Loa, Hualālai, and Haleakalā. It includes open shrublands, grasslands, and deserts...

, and is a colonizer
Ruderal species
A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural , or due to human influence – constructional , or agricultural .Ruderal species typically dominate the disturbed area...

 of recent lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 flows. It is relatively slow growing. Dominant in cloud forests above 400 m (1,312.3 ft), the tree is also common in seasonally wet forests, where it may be dominant or form mixtures with the native Acacia koa.

Habitat

Metrosideros polymorpha may occur as a tall tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 or a prostrate shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

, and everything in between. Preferred soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

s are acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic to neutral (pH
Soil pH
The soil pH is a measure of the acidity or basicity in soils. pH is defined as the negative logarithm of the activity of hydrogen ions in solution. It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic and above 7 is basic. Soil pH is considered a master variable in soils as it...

 3.6-7.4) and either a Histosol
Histosol
In both the FAO soil classification and the USA soil taxonomy, a histosol is a soil consisting primarily of organic materials. They are defined as having or more of organic soil material in the upper . Organic soil material has an organic carbon content of 12 to 18 percent, or more, depending on...

, Mollisol, Podsol
Podsol
In soil science, podzols are the typical soils of coniferous, or boreal forests. They are also the typical soils of eucalypt forests and heathlands in southern Australia...

, Oxisol
Oxisol
Oxisols are an order in USDA soil taxonomy, best known for their occurrence in tropical rain forest, 15-25 degrees north and south of the Equator. Some oxisols have been previously classified as laterite soils.-Formation:...

, Ultisol, or Alfisol. Rainfall of 1000 – per year is favored, but ōhia can grow in dry forests
Hawaiian tropical dry forests
The Hawaiian tropical dry forests are a tropical dry broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of on the leeward side of the main islands and the summits of Niihau and Kahoolawe. These forests are either seasonal or sclerophyllous. Annual rainfall is less than and...

 that receive as little as 400 mm (15.7 in) or bogs that get more than 10000 mm (393.7 in) of rain. On moist, deep soils, ōhia grows to 20 – high. Specimens reaching 30 m (98.4 ft) high are on record. The trunk varies in form. In some trees, it is straight and smooth; in others, it is twisted and prominently fluted. Trees growing in forests often have stilt roots, having germinated
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

 on logs or the stems of fallen hāpuu (Cibotium
Cibotium
Cibotium is a genus of eleven species of tropical tree fern—subject to much confusion and revision—distributed fairly narrowly in Hawaii , Southeast Asia , and the cloud forests of Central America and Mexico...

tree ferns), which have long decayed
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 away when the tree has reached maturity. Some trees have fibrous aerial root
Aerial root
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rātā and pōhutukawa Aerial roots...

s to gather moisture. At high elevations, and in areas with poor soils or little rainfall, shrub forms are the norm. Flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s 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 stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...

s extend from the flower and give the blossoms their characteristic pom-pon
Pom-pon
A pom-pon is a fluffy, decorative ball or tuft. Pom-pons may come in many colors, sizes, and varieties and are made from a wide array of materials, including wool, cotton, paper, plastic, and occasionally feathers....

 shape.

Uses

The reddish brown heartwood of M. polymorpha is very hard, fine textured, and has a specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of 0.7. In native Hawaiian society
Native Hawaiians
Native Hawaiians refers to the indigenous Polynesian people of the Hawaiian Islands or their descendants. Native Hawaiians trace their ancestry back to the original Polynesian settlers of Hawaii.According to the U.S...

, it was used in house and heiau
Heiau
A heiau is a Hawaiian temple. Many types of heiau existed, including heiau to treat the sick , offer first fruits, offer first catch, start rain, stop rain, increase the population, ensure health of the nation, achieve success in distant voyaging, reach peace, and achieve success in war . Only the...

construction, as well as to make papa kui ai (poi
Poi (food)
Poi is a Hawaiian word for the primary Polynesian staple food made from the corm of the taro plant . Poi is produced by mashing the cooked corm until it is a highly viscous fluid...

 boards), weapons, tool handles, hohoa (round kapa
Kapa
Kapa is a fabric that was made by Native Hawaiians from the bast fibres of certain species of trees and shrubs in the orders Rosales and Malvales. It is similar to tapa found elsewhere in Polynesia but differs in the methods used in its creation...

beaters), and kii
Tiki
Tiki refers to large wood and stone carvings of humanoid forms in Central Eastern Polynesian cultures of the Pacific Ocean. The term is also used in Māori mythology where Tiki is the first man, created by either Tūmatauenga or Tāne. He found the first woman, Marikoriko, in a pond – she seduced him...

(statues and idols). Although the trunk of ōhia was not used to make the kaele (hull) of waa (outrigger canoe
Outrigger canoe
The outrigger canoe is a type of canoe featuring one or more lateral support floats known as outriggers, which are fastened to one or both sides of the main hull...

s), it was used for their nohona waa (seats), pale (gunwale
Gunwale
The gunwale is a nautical term describing the top edge of the side of a boat.Wale is the same word as the skin injury, a wheal, which, too, forms a ridge. Originally the gunwale was the "Gun ridge" on a sailing warship. This represented the strengthening wale or structural band added to the design...

s), and pola (decking). Wae (spreaders) were made from the curved stilt roots of ōhia. (fencing) was made from the wood due to its availability; kauila (Colubrina oppositifolia
Colubrina oppositifolia
Colubrina oppositifolia, known as Kauila in Hawaiian, is a species of flowering tree in the buckthorn family, Rhamnaceae, that is endemic to Hawaii. It can be found in dry, coastal mesic, and mixed mesic forests at elevations of on the islands of Oahu and Hawaii . There is also one individual...

or Alphitonia ponderosa
Alphitonia ponderosa
Alphitonia ponderosa is a species of flowering tree in the buckthorn family, Rhamnaceae, that is endemic to the Hawaiian Islands. It is locally known as kauila, as is the related Colubrina oppositifolia.-Description:A...

), more durable woods when in contact with soil, was rarer. As the wood burned hot and cleanly, it was excellent wahie (firewood
Wood fuel
Wood fuel is wood used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood fuel may be available as...

). The lehua (flowers) and liko lehua (leaf buds) were used in making lei
Lei (Hawaii)
Lei is a Hawaiian word for a garland or wreath. More loosely defined, a lei is any series of objects strung together with the intent to be worn. The most popular concept of a lei in Hawaiian culture is a wreath of flowers draped around the neck presented upon arriving or leaving as a symbol of...

. The flowers were used medicinally
Herbalism
Herbalism is a traditional medicinal or folk medicine practice based on the use of plants and plant extracts. Herbalism is also known as botanical medicine, medical herbalism, herbal medicine, herbology, herblore, and phytotherapy...

 to treat pain experienced during childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

.

Ōhia lehua is one of the few honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...

 plants that is native to the Hawaiian Islands.

Similar species

There are about 50 species in the genus Metrosideros
Metrosideros
Metrosideros is a genus of approximately 50 trees, shrubs, and vines native to the islands of the Pacific Ocean, from the Philippines to New Zealand and including the Bonin Islands, Polynesia, and Melanesia, with an anomalous outlier in South Africa. Most of the tree forms are small, but some are...

in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

 and the Pacific
Pacific Islands
The Pacific Islands comprise 20,000 to 30,000 islands in the Pacific Ocean. The islands are also sometimes collectively called Oceania, although Oceania is sometimes defined as also including Australasia and the Malay Archipelago....

, including four other, much more localized species in Hawaii - M. macropus
Metrosideros macropus
Lehua mamo , 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 , found throughout the islands. Lehua mamo, however, is only found in the Koolau mountains. ...

(lehua mamo), M. rugosa
Metrosideros rugosa
Metrosideros rugosa , is a tree of the myrtle family which is endemic to the island of Oahu in the Hawaiian Islands. It is closely related to the widespread and highly variable ōhia lehua , found throughout the islands...

(lehua papa), M. tremuloides (lehua āhihi), and M. waialealae (Wagner et al. 1999). They are easily confused with M. polymorpha, and are best distinguished by their leaves.

Metrosideros kermadecensis
Metrosideros kermadecensis
Metrosideros kermadecensis, commonly called the is an evergreen tree of the myrtle family which is endemic to the volcanic Kermadec Islands about 900 km north-east of New Zealand. The tree produces a brilliant display of red flowers, made up of a mass of stamens and is the dominant forest tree on...

, from the Kermadec Islands
Kermadec Islands
The Kermadec Islands are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga...

 north of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, has recently become naturalized on Maui
Maui
The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

 and may become a pest species. Several cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...

s of M. excelsa, the Pōhutukawa tree of New Zealand, have been sometimes planted as ornamentals in Hawaii but are not reported to have naturalized. Metrosideros polymorpha was originally classified as a variety of M. collina
Metrosideros collina
Metrosideros collina is a species of flowering plant in the family Myrtaceae. It is native to the Marquesas Islands, Society Islands, Fiji and Vanuatu. In the Samoa Islands, the plant is indigenous to the islands of Savai'i, Upolu and Tutuila.-Taxonomy:The species was first formally described by...

, native to Rarotonga
Rarotonga
Rarotonga is the most populous island of the Cook Islands, with a population of 14,153 , out of the country's total population of 19,569.The Cook Islands' Parliament buildings and international airport are on Rarotonga...

, Tahiti
Tahiti
Tahiti is the largest island in the Windward group of French Polynesia, located in the archipelago of the Society Islands in the southern Pacific Ocean. It is the economic, cultural and political centre of French Polynesia. The island was formed from volcanic activity and is high and mountainous...

, and other islands of Polynesia
Polynesia
Polynesia is a subregion of Oceania, made up of over 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are termed Polynesians and they share many similar traits including language, culture and beliefs...

, but now is generally accepted as a distinct Hawaiian endemic species.

Conservation

Metrosideros polymorpha forests in Hawaii have been invaded by a myriad of alien species. In the wet forests these include the strawberry guava
Strawberry guava
Psidium cattleianum, named in honour of notable English horticulturist Sir William Cattley, commonly known as Cattley guava or Peruvian guava, is a small tree , bearing small red or yellow fruit, which are somewhat sour but sometimes eaten or made into jam...

 (Psidium littorale), albizia (Falcataria moluccana), and "purple plague" (Miconia calvescens
Miconia calvescens
The velvet tree, miconia, or bush currant is a species of flowering plant in the family Melastomataceae. It is native to Mexico and Central and South America but is best known for being arguably the worst invasive plant in Hawaii, where it is commonly referred to as the "purple plague", and...

). In drier areas, problematic invaders include faya tree (Myrica faya
Myrica faya
Myrica faya is a species of Myrica, native to Macaronesia , and possibly also southern Portugal....

) and Christmasberry (Schinus terebinthifolius). Alien grasses such as meadow ricegrass (Ehrharta
Ehrharta
Ehrharta is a genus of about 25 to 35 species of grass mostly native to Africa, with a few species native to the Mascarene Islands and Indonesia. The genus is also found in Yemen, China, Europe and North America and there are several invasive species including Ehrharta longiflora, Ehrharta calycina...

 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
Grevillea robusta
Grevillea robusta, commonly known as the southern silky oak or Silky-oak, or Australian Silver-oak, is the largest species in the genus Grevillea. It is a native of eastern coastal Australia, in riverine, subtropical and dry rainforest environments receiving more than 1,000 mm per year of...

) and fountain grass (Pennisetum setaceum). While ōhia itself remains extremely abundant, some species that depend on it such as the akekee
‘Akeke‘e
The Akekee is a bird species in the family Fringillidae, where it is placed in the Hawaiian honeycreeper genus Loxops. It is endemic to the island of Kauai where it is found in small numbers in higher elevations...

 (Loxops caeruleirostris) and longhorn beetle
Longhorn beetle
The longhorn beetles are a cosmopolitan family of beetles, typically characterized by extremely long antennae, which are often as long as or longer than the beetle's body...

s in the genus Plagithmysus have become endangered due to shrinkage of forest areas.

Etymology

The generic name Metrosideros derives from the Ancient Greek metra or "heartwood" and sideron or "iron". The species name polymorpha is also from Ancient Greek, and means "many forms". The Hawaiian language
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

 word ōhia derives from Proto-Oceanic *kafika, the name of the Mountain Apple tree, Syzygium malaccense, while Lehua derives from Proto-Central Eastern Polynesian *refua, the name of a star, perhaps Antares
Antares
Antares is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky . Along with Aldebaran, Spica, and Regulus it is one of the four brightest stars near the ecliptic...

. The Malay Apple tree has red flowers similar to those of Metrosideros species, and Antares is a bright red star.

Mythology

In Hawaiian mythology
Hawaiian mythology
Hawaiian mythology refers to the legends, historical tales and sayings of the ancient Hawaiian people. It is considered a variant of a more general Polynesian mythology, developing its own unique character for several centuries before about 1800. It is associated with the Hawaiian religion...

, Ōhia and Lehua were two young lovers. The volcano goddess Pele fell in love with the handsome Ōhia and approached him, but he turned down her advances. In a fit of jealousy, Pele transformed Ōhia 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 ōhia tree. Other versions say that Pele felt guilty but was unable to reverse the change, so she turned Lehua into a flower herself. Separating these united lovers is not encouraged, and it is said that when a lehua flower is plucked from an ōhia tree, the sky fills with rain representing the lovers' tears.
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