''Sesbania tomentosa'', commonly known as Oahu riverhemp and ''ōhai'', is an endangered species of plant in the pea family,

Fabaceae Fabaceae () or Leguminosae,International Code of Nomen ...

, that is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the main

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 ...

as well as

Nihoa Nihoa (; or ), also known as Bird Island or Moku Manu, is the tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands (NWHI). The island is located at the southern end of the NWHI chain, southeast of Necker ...

and Necker Island. It inhabits low shrublands and, rarely,

dry forests The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...

, at elevations from sea level to . Associated native plant species include akiaki (''

Sporobolus virginicus ''Sporobolus virginicus'', known by numerous common names including seashore dropseed, marine couch, sand couch, salt couch grass, saltwater couch, coastal rat-tail grass, and nioaka, is a species of Poaceae, grass with a wide distribution. Desc ...

''), ilima (''

Sida fallax ''Sida fallax'', known as yellow ilima, golden mallow,, or Ilima is a species of Herbaceous plant, herbaceous flowering plant in the ''Hibiscus'' family, Malvaceae, indigenous to the Hawaiian Archipelago and other Pacific Islands. Plants may be e ...

''), naupaka kahakai (''

Scaevola taccada ''Scaevola taccada'', also known as beach cabbage, sea lettuce, or beach naupaka, is a flowering plant in the family Goodeniaceae found in mangrove swamps and rocky or sandy coastal locations in the tropical areas of the Indo-Pacific. It is a co ...

''), and pili (''

Heteropogon contortus ''Heteropogon contortus'' is a tropical, perennial tussock grass with a native distribution encompassing Southern Africa, southern Asia, Northern Australia, Oceania, and southwestern North America. The species has also become a naturalised weed ...

''). Off-road vehicles,

wildfire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...

s, grazing, and alien species competition have destroyed their habitat on the main islands, but they are still quite common on Nihoa and Necker. At least 2000 specimens grow on Nihoa, while there are far less on Necker. ''Ōhai'' is highly polymorphic, exhibiting broad variations in color and shape. Plants that grow on Nihoa have reddish-orange flowers and young leaflets that are relatively hairless. Necker plants have salmon to orange colored-flowers, and leaflets that are very hairy. A form that grows as a standing tree exists on

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 ...

. ''Ōhai'' grows as a prostrate shrub with semi-

glaucous ''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), ...

hairless leaves on the southernmost tip of the

island of Hawaii Hawaii is the List of islands of the United States by area, largest island in the United States, located in the Hawaii, state of Hawaii, the southernmost state in the union. It is the southeasternmost of the Hawaiian Islands, a chain of volcani ...

Ka Lae Ka Lae (), also known as South Point, is the southernmost point of the Hawaii (island), Big Island of Hawaii and Extreme points of the United States, of the 50 United States. The Ka Lae area is registered as a National Historic Landmark, Natio ...

References

External links

* * * * Faboideae Plants described in 1838 Endemic flora of Hawaii {{Faboideae-stub