Brighamia is a small genus of two species in the bellflower family Campanulaceae, order Asterales, endemic to the Hawaiian Islands. The plants are immediately recognisable by their swollen, succulent stem — which can grow to a metre or more — topped by a dense rosette of broad, fleshy leaves, giving them a silhouette reminiscent of a miniature palm or a bowling pin. Long, slender, tubular white flowers emerge from the crown and are adapted for pollination by hawkmoths, principally the endangered endemic Hawaiian hawkmoth Manduca blackburni. The bark exudes a milky latex. Fruits are dry capsules.
The genus was described by Asa Gray in 1867, with Brighamia insignis A.Gray as the type species. It belongs to subfamily Lobelioideae and sits within the Hawaiian lobelioids, the largest plant radiation on any island archipelago, comprising more than 125 species across six genera. A molecular phylogenetic study published in 2021 placed Brighamia in a clade with Delissea and several Lobelia sections, related to giant lobelioids of Africa and South America; the ancestral colonist likely arrived in Hawaii approximately 13 million years ago.
Both species are critically threatened. Brighamia rockii (Pua ʻAla), found historically on Molokaʻi, Lānaʻi, and Maui, is classified as Critically Endangered. Brighamia insignis (ʻŌlulu), from Kauaʻi and Niʻihau, is classified as Extinct in the Wild. Their cliff-face habitat has offered some protection from introduced herbivores, but the near-extinction of their primary pollinator has made natural reproduction nearly impossible. Both are maintained in ex-situ collections at botanic gardens, and B. insignis has found a modest second life as a houseplant, though cultivated populations have limited genetic diversity.
Etymology
The genus is named in honour of William Tufts Brigham (1841–1926), an American geologist, botanist, and ethnologist who served as the first director of the Bernice P. Bishop Museum in Honolulu, Hawaii.
Distribution
Brighamia is endemic to the Hawaiian Islands. Brighamia insignis (ʻŌlulu) is native to Kauaʻi and Niʻihau; B. rockii (Pua ʻAla) is native to Molokaʻi, with historical populations on Lānaʻi and Maui now believed extinct. Both species grow on steep, often inaccessible sea cliffs.
Ecology
Brighamia species grow on precipitous coastal and inland cliffs, a habitat that provided some natural protection from introduced herbivores such as feral pigs and rats that devastate other Hawaiian lobelioids. The long, tubular white flowers are adapted for hawkmoth pollination; the primary pollinator is the endangered endemic Hawaiian hawkmoth (Manduca blackburni), which now survives mainly on the southern slopes of Maui, away from remaining wild Brighamia populations. Some pollination may occur via introduced hawkmoths (M. quinquemaculata, Agrius cingulata). Because natural pollination is now extremely rare, botanists have resorted to hand-pollination to ensure seed set.
Conservation
Brighamia rockii is listed as Critically Endangered (CR) and B. insignis as Extinct in the Wild (EW) on the IUCN Red List. The near-extinction of their primary pollinator, Manduca blackburni, makes natural reproduction nearly impossible. Both species are maintained in ex-situ collections in botanic gardens worldwide. B. insignis is also grown as a houseplant, though cultivated populations carry only limited genetic diversity.
Cultivation
Brighamia insignis is cultivated as a houseplant — its compact, architectural form (a swollen succulent base topped by a leaf rosette) makes it an ornamental curiosity. It tolerates indoor conditions but requires hand-pollination to set seed, since its hawkmoth pollinator does not exist outside Hawaii.
