Cyanea undulata 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 names wavy cyanea and leechleaf cyanea. It is endemic to 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",...

, where it is in rapid decline. It 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. Like other Cyanea

Cyanea (plant)

Cyanea is a genus of lobelioid plants endemic to Hawaii. It contains more than 50 species, ranging in size from shrubs like C. eleeleensis to tall palm-like trees over 10 meters tall such as C. leptostegia...

it is known as haha in Hawaiian

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...

.

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...

 which can exceed three meters in height. The leaves have wavy edges and the flowers are yellow.

The plant was first described in 1909 and then it was not seen again until it was rediscovered in 1991. In 1994 there was a single population containing 28 plants. By 2006 the population was in poor shape, with a single mature plant and a few juveniles remaining.

The species has become rare because of habitat degradation by feral pigs, 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...

, and damage to plants caused by 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.