Cyanea rivularis is a rare species of flowering plant in the bellflower family

Campanulaceae

The family Campanulaceae , of the order Asterales, contains about 2000 species in 70 genera of herbaceous plants, shrubs, and rarely small trees, often with milky non-toxic sap...

 known by the common name plateau cyanea. 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 three small populations of the plant remaining in the wild, for a total of 19 individual plants. 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 1996.

This Hawaiian lobelioid

Hawaiian lobelioids

The Hawaiian lobelioids are a group of flowering plants in the bellflower family, Campanulaceae, all of which are endemic to the Hawaiian Islands. This is the largest plant radiation in the Hawaiian Islands, and indeed the largest on any island archipelago, with over 125 species...

 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 4 to 5 meters tall. It bears blue-striped white flowers. It grows in wet forest habitat, generally next to stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

s, waterfall

Waterfall

A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...

s, and plunge pool

Plunge pool

A plunge pool can be a natural hydrologic fluvial landform feature or a constructed recreational garden feature...

s. Other plants in the habitat include ōhia lehua

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) and 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), which dominate the canopy, 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), ieie

Freycinetia arborea

The Ieie is a densely branched, brittle, woody climber in the screwpalm family, Pandanaceae that is endemic to the Pacific Islands. Ieie is found in moist forest on the Hawaiian, Marquesas, Austral, Society, and Cook Islands. It grows into the forest canopy, attaching itself to a host tree using...

 (Freycinetia arborea) and aiea

Ilex anomala

Ilex anomala, commonly known as Kāwau or Aiea, is a species of holly that is endemic to Hawaii. It inhabits mixed mesic and wet forests at elevations of on all main islands....

 (Ilex anomala) in the understory

Understory

Understory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...

.

This ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

 is threatened by exotic plant species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 such as Koster's curse

Clidemia hirta

Clidemia hirta, commonly called soapbush or Koster's Curse, is a perennial shrub.It is an invasive plant species in many tropical regions of the world, creating serious damage.-Distribution:...

 (Clidemia hirta), Kahili ginger

Hedychium gardnerianum

Hedychium gardnerianum is a plant native to the Himalayas in India, Nepal, and Bhutan. It grows to 8 ft tall with long, bright green leaves clasping the tall stems. The very fragrant pale yellow and red flowers are held in dense spikes above the foliage...

 (Hedychium gardnerianum), and 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). Feral

Feral

A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...

 ungulate

Ungulate

Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...

s damage the habitat, and 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 and slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

s damage plants.