Eugenia koolauensis, commonly known as Koolau Eugenia or Nioi, is a species of flowering plant

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...

 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...

. It is endemic to 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...

, where it could previously be found on the islands of Molokai

Molokai

Molokai or Molokai is an island in the Hawaiian archipelago. It is 38 by 10 miles in size with a land area of , making it the fifth largest of the main Hawaiian Islands and the 27th largest island in the United States. It lies east of Oahu across the 25-mile wide Kaiwi Channel and north of...

 and Oahu

Oahu

Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...

; today populations only exist on the latter. This is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States.

This is one of two Eugenia species native to Hawaii, and the only endemic. It is a 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...

 or 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...

 grows 2 to 7 meters tall. The tips of the branches and the undersides of the leaves are hairy. White flowers occur in the leaf axils

It inhabits dry gulches and ridges in coastal mesic and mixed mesic forests on the Koolau and Waianae Ranges

Waianae Range

Waianae Range is the eroded remains of an ancient shield volcano that comprises the western half of the Hawaiian Island of Oahu...

. Associated plant species include maile (Alyxia oliviformis), ahakea lau nui (Bobea

Bobea

Bobea is a genus of flowering plants in the coffee family, Rubiaceae. All species in this genus are endemic to Hawaii. . Bobea was named for Jean-Baptiste Bobe-Moreau by Charles Gaudichaud-Beaupré in 1830 in his book Voyage de l'Uranie.The wood of Bobea is hard, wearable, and yellow. It was used...

 elatior), Carex

Carex

Carex is a genus of plants in the family Cyperaceae, commonly known as sedges. Other members of the Cyperaceae family are also called sedges, however those of genus Carex may be called "true" sedges, and it is the most species-rich genus in the family. The study of Carex is known as...

 meyenii, uluhe (Dicranopteris linearis

Dicranopteris linearis

Dicranopteris linearis is a common species of fern known by many common names, including Old World forked fern and uluhe . It is one of the most widely distributed ferns of the wet Old World tropics and adjacent regions, including Polynesia and the Pacific...

), kōlea lau nui (Myrsine lessertiana

Myrsine lessertiana

Kōlea lau nui is a species of colicwood that is endemic to Hawaii. It inhabits dry, coastal mesic, mixed mesic, and wet forests at elevations of on all main islands. M...

), olopua (Nestegis sandwicensis

Nestegis sandwicensis

Nestegis sandwicensis, commonly known as Olopua, is a species of flowering tree in the olive family, Oleaceae, that is endemic to Hawaii. It is found on all major islands at elevations of in coastal mesic and mixed mesic forests, and, especially, dry forests...

), hala pepe (Pleomele halapepe

Pleomele halapepe

Pleomele halapepe is a species of flowering plant that is endemic to the island of Oahu in Hawaii. It inhabits dry, coastal mesic and mixed mesic forests at elevations of . It is threatened by habitat loss.-References:...

), ālaa (Pouteria sandwicensis

Pouteria sandwicensis

Pouteria sandwicensis is a species of flowering tree in the sapodilla family, Sapotaceae, that is endemic to the main islands of Hawaii. Names for this species in the Hawaiian language include Ālaa, Āulu and Ēlaa....

), alahee (Psydrax odorata

Psydrax odorata

Psydrax odorata, known as Alahee in Hawaiian, is a species of flowering shrub or small tree in the coffee family, Rubiaceae, that is native to the Pacific Islands, Malesia and Australasia...

), hao (Rauvolfia sandwicensis

Rauvolfia sandwicensis

Rauvolfia sandwicensis, known as Hao in the Hawaiian language, is a species of flowering plant in the milkweed family, Apocynaceae, that is endemic to Hawaii. It is a shrub, a small tree reaching in height, or, rarely, a medium-sized tree up to tall with a trunk diameter of . Hao inhabits...

), and pūkiawe (Styphelia tameiameiae

Styphelia tameiameiae

Styphelia tameiameiae, known as Pūkiawe in the Hawaiian language, is a species of flowering plant in the heather family, Ericaceae, that is native to the Hawaiian and Marquesas Islands. The specific epithet honors King Kamehameha I, who formed the Kingdom of Hawaii. It grows as a tree up to tall...

).

It is threatened by habitat loss and recently Puccinia psidii

Puccinia psidii

Puccinia psidii is a rust native to Brazil with a very broad host range in the myrtle family . Puccinia psidii can have very serious consequences to various species of plants in the Myrtaceae...

, a non-native fungal disease.

In 2008 there were fewer than 300 mature plants in the Koolau Range and only three in the Waianae Range. It is extirpated

Local extinction

Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...

 from the island of Molokai, where its former habitat was cleared for pineapple

Pineapple

Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...

fields.

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