Exocarpos luteolus is a rare species of flowering plant in the sandalwood family

Santalaceae

Santalaceae is a widely distributed family of flowering plants which, like other members of Santalales, are partially parasitic on other plants...

 known by the common name heau. 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 is known only from the island of Kauai

Kauai

Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...

. There are eight populations remaining, for a total global population of only 39 individuals. The plant was federally listed as an 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 in 1994.

This plant 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...

 growing one half to two meters tall. There are two types of leaves, lance-shaped to oval leaf blades up to 8 centimeters long and smaller, reduced leaves that are like scales. Some plants have only scale-like leaves and appear leafless at first glance. The flower has six greenish petals each about a millimeter long. The fruit is a yellow drupe

Drupe

In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...

 between 1 and 2 centimeters long.

This rare plant grows in several types of habitat, including bog

Bog

A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....

s, open ridges, and closed wet forests. Plants sharing the forested habitat types may include ohia

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, and much smaller when growing in boggy soils or on basalt...

 (Metrosideros polymorpha), uluhe

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...

 (Dicranopteris linearis), koa (Acacia koa), kauila

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...

 (Alphitonia ponderosa), and poʻola nui (Bidens cosmoides). Plants in its bog habitat may include pa iniu

Astelia waialealae

Astelia waialealae is a rare species of plant in the Asteliaceae family that is endemic to the island of Kauai of the state of Hawaii in United States. It inhabits montane bogs within the vicinity of the Alakai Swamp on the island's central plateau. A. waialealae is threatened by habitat loss and...

 (Astelia waialealae), and kanawao

Broussaisia

Kanawao is a species of perennial flowering plant in the Hydrangea family, Hydrangeaceae, that is endemic to Hawaii. It belongs to a monotypic genus....

 (Broussaisia arguta).

This plant is nearing extinction

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 because of a number of threats, mainly habitat destruction

Habitat destruction

Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and degradation from feral goat

Feral goat

The feral goat is the domestic goat when it has become established in the wild. Feral goats occur in Australia, New Zealand, Ireland, Great Britain, Hawaii, the Galapagos and in many other parts of the world...

s and pigs. Rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s consume the seeds. Many invasive plant species

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 are present in the habitat, including prickly blackberry (Rubus argutus), banana poka

Passiflora tarminiana

Passiflora tarminiana is a species of passionfruit. The yellow fruits are edible and their resemblance to small, straight bananas has given it the name banana passionfruit in some countries. It is native to the uplands of tropical South America and is now cultivated in many countries. In Hawai'i...

 (Passiflora tarminiana), Santa Barbara daisy

Erigeron karvinskianus

Erigeron karvinskianus is a species of flowering plant in the daisy family known by the common name Latin American fleabane, though some know it as the Santa Barbara daisy....

 (Erigeron karvinskianus) paii iha

Christella dentata

Christella dentata is a small fern with widespread distribution in Australia and islands in the south Pacific Ocean. There are many local common names. In New South Wales it grows north from the southern Illawarra region and is known as Binung....

 (Christella dentata), lantana

Lantana camara

Lantana camara, also known as Spanish Flag or West Indian Lantana, is a species of flowering plant in the verbena family, Verbenaceae, that is native to the American tropics. It has been introduced into other parts of the world as an ornamental plant and is considered an invasive species in many...

 (Lantana camara), and molasses grass

Melinis minutiflora

Melinis minutiflora, commonly known as molasses grass, is a species of grass. It has been weedy in Australia, where it has been introduced....

(Melinis minutiflora).