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Updated 9/26/2016

Endangered Hawaiian Plants

Approximately 1000 species of flowering plants are native to the Hawaiian Islands, 89% of which are endemic to the region.  Many of Hawaii's endemic plants have been driven to extinction due to a number of human-induced forces including deforestation, urbanization, agriculture, ranching, over-harvesting, alien species, and disease.  Some may have been common at one time or limited to a few individuals.  Presumably a few had already been driven to extinction before Western contact.  Efforts to protect these remnants include the Endangered Species Act, creation of National Wildlife Refuges, State Natural Area Reserves, private preserves (TNC), fencing to exclude mammals, invasive species control.  Propagation efforts by botanical gardens, nurseries & private citizens allow many of these rarities to survive and be appreciated.


Family Fabaceae

Sesbania tomentosa   

Kaena Point, Oahu


Endangered shrub formerly common on coastal dunes, and rocky outcrops.  Has silvery leaves coated with dense hairs to reflect sunlight.  Endemic to Hawaii.


Acacia koaia   

Ho'omaluhia, Kaneohe, Oahu


Rare endangered tree of dry forests of Hawaii, Maui, Lana'i, & Moloka'i.  Distinguished from Acacia koa by its small contorted form, shorter, straighter  phyllodes, smaller pods, and extremely hard wood.  


Caesalpinia kavaiensis


Kapi'olani Garden, Oahu


Critically endangered tree from mesic or dry forest, probably widespread long ago but now limited to wild populations on leeward Oahu and the Big Island.  Easily identified by the flattened oval pods and salmon flowers.  Formerly known as Mezoneuron kavaiense.



Family Asteraceae

Argyroxiphium sandwicense subsp. sandwicense



Mauna Kea State Park, Hawaii


Scattered on cinder in alpine zone of Haleakala on Maui.  Narrow leaves' silver hairs reflect UV radiation and gel-filled core stores moisture.  Blooms once then dies.  Threatened with extinction due to grazing, habitat alteration, trampling of delicate root system, and loss of natural pollinators.  Endangered subspecies sandwicense occurs as a single population on Mauna Kea, Hawaii.  Flowers in each subspecies differ substantially.




Argyroxiphium sandwicense subsp. macrocephalum

Haleakala, Maui


Extremely rare in a single location on the upper slope of Mauna Kea.  Narrow leaves' silver hairs reflect UV radiation and gel-filled core stores moisture.  Blooms once then dies.  Threatened with extinction due to grazing, habitat alteration, trampling of delicate root system, and loss of natural pollinators.  The more common Haleakala Silversword occurs on Maui.  Flowers in each subspecies differ substantially.


Bidens amplectens 

Kealia, O'ahu


Small endangered shrub restricted to windward cliffs of O'ahu's northern Wai'anae Mountains.  Large flowers exceeding 3 inches in diameter.  Hybridizes with Bidens torta on leeward slopes.


Family Goodeniaceae

Scaevola coriacea   

Waiehu dunes, Maui


Prostrate perennial of consolidated coastal dunes.  Succulent leaves 1 - 2 inches long.  Formerly found on the main islands but nearly extinct due to habitat alteration or loss.  Federally Endangered.


Family Rubiaceae

Gardenia brighamii  

Koko Crater BG, Oahu


Small endangered tree from dry forests of Oahu to Hawaii.  Flower about 2 inches in diameter.  Only a few wild plants remaining but widely cultivated.


Family Malvaceae

Hibiscus arnottianus subsp. immaculatus


Endangered and native to Moloka'i's Wailau Valley.  Has a white staminal column and shiny, toothed leaves.


Hibiscus clayi   

Koko Crater, Oahu


Rare endangered shrub or small tree from dry forests of eastern Kaua'i.  Flowers & leaves smaller than H. kokio.  Acuminate leaves usually have smooth margins.  Formerly known as H. newhousei.



Hibiscus brackenridgei subsp. brackenridgei  

Kapi'olani Flower Garden, Oahu


Endangered shrub or small tree from dry forests of Moloka'i, Lana'i, Maui, & Hawaii.  Young stems, calices, & leaf undersides covered with short velvety hairs, flower buds lack reddish brown spots.


Hibiscus brackenridgei subsp. mokuleianus 

Cultivated, Waimanalo, Oahu


Endangered shrub or small tree from dry forests of Kaua'i & Oahu.  Young stems & calyx covered with sharp, stinging hairs, leaves somewhat shiny, flower buds with reddish brown spots.


Abutilon eremitopetalum


Extremely rare shrub of dry forest now known from a single location on Lana'i.  Unique green flowers with petals that remain hidden.  Endemic to Hawaii.

More info (PDF)


Abutilon menziesii   


Small clump-forming shrub rare and endangered in dry forest of the Main Hawaiian Islands.  An attractive plant widely maintained in cultivation.  Pale to deep red flowers 1.5 inch in diameter.  Endemic to Hawaii.



Family Campanulaceae

Brighamia insignis

Kapi'olani Flower Garden, Oahu




Endangered succulent subshrub of Kaua'i's arid Na Pali cliffs, where a single wild plant remains.  Fortunately it has been propagated and distributed among botanical gardens.  Showy yellow flowers are now pollinated by hand since its natural moth host is presumed extinct.  The white-flowered Brighamia rockii occurs on windward cliffs of Moloka'i & Maui.



Cyanea grimesiana subsp. obatae

Palikea, O'ahu




Endangered palmate shrub in mesic forest of the Southern Wai'anae Mountains.  Spiny, with purple and white flowers.  Subspecies grimesiana occurs in the Northern Wai'anae Mountains east to Maui, differing in shape and size of calyx lobes.


Family Euphorbiaceae

Euphorbia celastroides var. kaenana   

Ka'ena Point, Oahu


Endangered shrub restricted to talus slopes at Ka'ena Point on Oahu.


Euphorbia celastroides var. laehiensis   

Waiopae, Maui


Endangered sprawling shrub on talus slopes of SE Maui & Lana'i.


Euphorbia deppeana   

Nu'uanu Pali, Oahu


Very rare sub shrub on windswept cliffs at Oahu's Nu'uanu Pali Lookout.  Thought to be extinct until its rediscovery in 1986.  Leaves lack hairs, with rounded apex & finely serrate margins.  Flowers 1.5 - 3mm wide, nearly sessile in leaf axil.


Family Amaranthaceae

Achyranthes splendens var. rotundata   

Ka'ena Point NAR, Oahu


Rare coastal shrub on dry rocky slopes & coral plains.  An endangered species occurring from Oahu to Maui.


Nototrichium humile

Kapi'olani Garden, Oahu


Endangered shrub in dry forests, slopes, & cliffs of NW Oahu & East Maui.


Nototrichium divaricatum


Kapi'olani Garden, Oahu


Endangered shrub from cliffs along Kaua'i's Na Pali coast.  First discovered in 1985.


Family Rutaceae

Platydesma cornuta var. decurrens   

Palikea, O'ahu


Endangered shrub of mesic forest or dry cliffs of O'ahu Wai'anae Mountains.  Palm-like with long leaves clustered at branch ends, this variety has leaf bases tapering gradually to the petiole.  About 300 wild plants are known.  Variety cornuta from the Ko'olau Mountains has leaf bases abruptly truncate where it joins the petiole.


Family Violaceae

Viola chamissoniana subsp. chamissoniana  


Palikea, O'ahu


Endangered subshrub on dry ridges of O'ahu's southern Wai'anae mountains.  Leaves thick and glossy with petioles less than an inch long, pale yellow flowers on peduncles less than an inch long.  The parent species occurs from Kaua'i to Maui.  Endemic to Hawa'i.


Family Araliaceae

Polyscias racemosa 

Kapi'olani Garden, Oahu


Endangered tree of mesic forest slopes on Kaua'i.  Attains height of 25 feet.  The unique pendant inflorescence led Sherff to create the monospecific genus Munroidendron.  It was reassigned to Polyscias in 2010.



Family Rhamnaceae

Colubrina oppositifolia   

Koko Crater BG, Oahu


Rare endangered tree of dry & mesic forests of West Oahu & Hawaii.  Prominent glands on underside of leaves.  Extremely hard wood was used in place of metal by Hawaiians.  The name Kauila is also used for Alphitonia ponderosa, another member of this family endemic to Hawaii.


Family Santalaceae

Exocarpos gaudichaudii

Palikea, O'ahu


Rare, almost leafless shrub or small tree of exposed cliffs in mesic forests of the Main Hawaiian Islands.  Fruit beaked, with a red receptacle.  Endemic to Hawai'i.


Family Arecaceae

Pritchardia remota   

Kapi'olani Garden, Oahu

Koko Crater, Oahu


Endemic to Nihoa Island where about 700 remain, it is now widely cultivated in gardens.  Attains height of 15 feet.  Federally listed Endangered Species.



Family Portulacaceae

Portulaca molokiniensis   

UH Manoa Campus


Rare from Molokini & two locations on Kaho'olawe.  Endemic to Hawaii.


Portulaca villosa   


Rare in dry rocky coastal lowlands from the island of Hawaii to Nihoa, excluding Kaua'i & Ni'ihau.  Flower varies from white to pink, 2cm diameter.  Seed capsules are papery, not shell-like as in Portulaca sclerocarpa.  Highly endangered & endemic to Hawaii.



Portulaca sclerocarpa   


Rare near steam vents on the flanks of Kilauea volcano; also found on Po'opo'o Islet , South Lana'i.  Seed capsules distinctively shell-like and difficult to open, compared to papery capsules in Portulaca villosa.  Vulnerable to extinction due to small population size.  I suspect it may hybridize with non-native Portulaca pilosa abundant at the Kilauea site.  Endemic to the Island of Hawaii & Lana'i.



Family Caryophyllaceae

Schiedea adamantis   

Koko Crater BG, Oahu


Small shrub up to 3 feet tall.  Federally listed Endangered Species.  A single wild population inhabits steep NW slopes of Le'ahi (Diamond Head).  A brush fire could destroy this rare plant.



Schiedea kealiae   


Kealia, Oahu



Lax subshrub rare and endangered along dry cliffs of the Northern Wai'anae Mountains.  Fewer than 300 plants are known.


Family Marsileaceae

Marsilea villosa 


Kapi'olani BG, O'ahu



Endangered species from arid scattered locations on Moloka'i and SE Oahu.  An ephemeral fern that briefly comes to life in waterlogged ground after soaking rains.  Spores are set as fronds wither and dry until the next wet season.  Fortunately the plant is easy to grow and propagate.


Family Solanaceae

Solanum nelsonii 

Kapi'olani BG, O'ahu


Sprawling endangered subshrub of coastal dunes primarily in the Northwestern Hawaiian Islands.  Leathery leaves are densely coated with short hairs.