''Hibiscus arnottianus'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

in the mallow family

Malvaceae Malvaceae (), or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include Theobroma cacao, cacao, Cola (plant), cola, cotton, okra, Hibiscus sabdariffa, ...

. It is a shrub or small tree native to the islands of

Oahu Oahu (, , sometimes written Oahu) is the third-largest and most populated island of the Hawaiian Islands and of the U.S. state of Hawaii. The state capital, Honolulu, is on Oahu's southeast coast. The island of Oahu and the uninhabited Northwe ...

and

Molokai Molokai or Molokai ( or ; Molokaʻi dialect: Morotaʻi ) is the fifth most populated of the eight major islands that make up the Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its g ...

in the

Hawaiian Islands The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...

, where it grows in

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

. The species is threatened by competition with invasive non-native plants and by predation and habitat degradation by introduced animals. Invasive plants alter its native habitat and compete for space, light, moisture, and nutrients. feral pigs ('' Sus domesticus''), goats ('' Capra hircus''), and

axis deer The chital or cheetal (''Axis axis''; ), also called spotted deer, chital deer and axis deer, is a deer species native to the Indian subcontinent. It was first described by Johann Christian Polycarp Erxleben in 1777. A moderate-sized deer, male ...

(''Axis axis'') damage plants and degrade the species' habitat by excessive browsing, trampling, and rooting for food. Introduced rats (''

Rattus rattus The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is ...

'') and introduced slugs and snails feed on plant parts and fruits. The species is also threatened by landslides, fire, and drought, which are worsened by habitat degradation. The species is assessed as

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

in the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

. Three subspecies are accepted. *''Hibiscus arnottianus'' subsp. ''arnottianus'' (synonym ''Hibiscus boryanus'' ) – native to the Waiʻanae Range of Oahu from 120 to 790 meters elevation. Subspecies ''arnottianus'' is assessed as endangered by the IUCN. *''Hibiscus arnottianus'' subsp. ''immaculatus'' (synonym ''Hibiscus immaculatus'' ) – native to eastern Molokai, including the Waihanau and Papalaua valleys, from 300 to 800 meters elevation. Subspecies ''immaculatus'' is assessed as

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

by the IUCN. *''Hibiscus arnottianus'' subsp. ''punaluuensis'' (synonym ''Hibiscus punaluuensis'' ) – native to the Koolau Range of eastern Oahu from 120 to 790 meters elevation. Subspecies ''punaluuensis'' is assessed as endangered by the IUCN.

References

{{Taxonbar, from= Q1617209 arnottianus Endemic flora of Hawaii Biota of Molokai Biota of Oahu Plants described in 1854 Taxa named by Asa Gray