Huperzia mannii is a species of lycopod plant known by the common names Mann's clubmoss and wawae`iole. 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 there are only six populations remaining. 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.

This plant is an epiphyte

Epiphyte

An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 which grows upon other plants, especially koa (Acacia koa), 'olapa

Cheirodendron trigynum

Cheirodendron trigynum, also known as Ōlapa or Common Cheirodendron, is a species of flowering plant in the ginseng family, Araliaceae, that is endemic to Hawaii. It is a medium-sized tree, reaching a height of and a trunk diameter of...

 (Cheirodendron trigynum), and kawa'u

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). It has a hanging, branching, reddish stem no more than 10 centimeters long. Each branch has three longitudinal rows of toothlike leaves. When reproducing the plant produces a branching fruiting spike which may be up to 20 centimeters long.

Today the plant is known from just a few occurrences on the islands of 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 Hawaii

Hawaii (island)

The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

. It is historically known from 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",...

, but it may be 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...

 there. Threats to its existence include damage to the habitat by feral pigs, cattle, and introduced 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 the fact that there are few individuals remaining.