Amaranthus brownii was an annual herb in the family Amaranthaceae. The plant was found only on the small island of Nihoa in the Northwestern Hawaiian Islands, growing on rocky outcrops at altitudes of 120–215 m (394–705 ft). It was one of nine species of Amaranthus in the Hawaiian Islands, as well as the only endemic Hawaiian species of the genus. It is now considered extinct.
Amastra micans, commonly known as the Amastrid land snail, is a species of land snail, a terrestrial pulmonate gastropod mollusk in the family Amastridae. It is a critically endangered species and endemic to the Hawaiian Islands, mainly found in the Waianae Mountains of Oahu.
Cyperus trachysanthos is a rare species of sedge known by the common names pu`uka`a and sticky flatsedge. It is endemic to Hawaii, where it is known from Kauai and Oahu. It was known from Niihau, Molokai and Lanai, but it has been extirpated from these islands. It is a federally listed endangered species of the United States.
Cyrtandra dentata is a rare species of flowering plant in the African violet family known by the common names mountain cyrtandra and sharp-toothed cyrtandra. It is endemic to Oahu in Hawaii, where the most recent count estimates 1640 plants occurring in the Waianae Mountains and Koʻolau Mountains. It is a shrub which can reach 5 meters tall and bears white flowers. It was federally listed as an endangered species in 1996. Like other Hawaiian Cyrtandra it is called ha`iwale.
Delissea subcordata is a rare species of flowering plant in the family Campanulaceae known by the common names Koʻolau Range delissea and oha. It is endemic to Hawaii, where it is known only from the island of Oahu. It is now only found in the Waianae Mountains, and it is believed to be extirpated from the Koʻolau Range, where it once occurred. As of 2008 there were 40 individuals remaining, 28 of which were mature plants. This plant was federally listed as an endangered species of the United States in 1996.
Diplazium molokaiense is a rare species of fern known by the common name Molokai twinsorus fern. It is endemic to Hawaii, where it is one of the rarest ferns. It has historically been found on the islands of Kauai, Oahu, Lanai, Molokai, and Maui, but it is thought to have been extirpated from four of them and today can be found only on Maui where fewer than 70 individual plants remain. The fern was federally listed as an endangered species of the United States in 1994.
Gouania meyenii is a rare species of flowering plant known by the common name smoothfruit chewstick or Meyen's gouania. It is endemic to Hawaii, where it is known only from Oahu and Kauai. It is estimated that there are between 38 and 63 individuals of this species remaining in the wild. It is a federally listed endangered species of the United States.
Cyperus pennatiformis is a rare species of sedge known by the common name coastal flatsedge. It is endemic to Hawaii, where it grows on the islands of Maui, Kauai, and Laysan. It is a federally listed endangered species of the United States.
Phyllostegia hirsuta is a species of flowering plant in the mint family known by the common names Molokai phyllostegia and hairy phyllostegia. It is endemic to Hawaii, where it is known only from the island of Oahu. It is a federally listed endangered species of the United States.
Peristylus holochila is a rare species of orchid known by the common name Hawaii bog orchid. It is endemic to Hawaii. It is a federally listed endangered species of the United States.
Poa mannii is a rare species of grass known by the common names Mann's bluegrass and Olokele Gulch bluegrass. It is endemic to Hawaii, where it is limited to the island of Kauai. It is threatened by the loss and modification of its habitat. It is a federally listed endangered species of the United States.
Poa sandvicensis is a rare species of grass known by the common name Hawaiian bluegrass. It is endemic to Hawaii, where it is limited to the island of Kauai. It is threatened by the loss and modification of its habitat. It is a federally listed endangered species of the United States.
Poa siphonoglossa is a rare species of grass known by the common names Kauai bluegrass and island bluegrass. It is endemic to Hawaii, where it is limited to the island of Kauai. It is threatened by the loss and modification of its habitat. It is a federally listed endangered species of the United States.
Sanicula mariversa is a rare species of flowering plant in the family Apiaceae known by the common name Waianae Range black-snakeroot. It is endemic to Hawaii, where it is known only from the Waianae Mountains on the island of Oahu. It is threatened by the degradation of its habitat. It is a federally listed endangered species of the United States.
Sanicula purpurea is a rare species of flowering plant in the carrot family known by the common names purple-flower black-snakeroot and purple-flowered sanicle. It is endemic to Hawaii, where it is known from Maui and from the Koolau Mountains on the island of Oahu. It is threatened by the degradation of its habitat. It was federally listed as endangered species of the United States in 1996.
Schiedea hookeri is a rare species of flowering plant in the family Caryophyllaceae known by the common names Hooker's schiedea and sprawling schiedea. It is endemic to Hawaii, where it is known only from the island of Oahu. It is thought to have been extirpated from Haleakalā on Maui. It is threatened by the degradation and destruction of its habitat. It was federally listed as an endangered species of the United States in 1996.
Schiedea kealiae is a rare species of flowering plant in the family Caryophyllaceae known by the common name Waianae Range schiedea. It is endemic to Hawaii, where it is known only from the Waianae Range on the island of Oahu. It is threatened by the degradation and destruction of its habitat. It was federally listed as an endangered species of the United States in 1996.
Silene lanceolata is a rare species of flowering plant in the family Caryophyllaceae known by the common names Kauai catchfly and lanceolate catchfly. It is endemic to Hawaii, where it is known only from Oahu, Molokai, and Hawaii, having been extirpated from Kauai and Lanai. It is threatened by the degradation of its habitat and it is a federally listed endangered species of the United States.
Viola oahuensis is a rare species of flowering plant in the violet family known by the common name Oahu violet.
