Search / Plant Profile / Hibiscus arnottianus ssp. immaculatus

Plant Profile

White Molokai Hibiscus (Hibiscus arnottianus ssp. immaculatus)

Closeup of white flower. Notice the white staminal column specific to this species. Photo Credit: D. Lorence

Global Rank: T1 - Critically Imperiled
Legal Status: Federally Endangered
Family: Malvaceae
State: HI
Nature Serve ID: 141480
Lifeform: Shrub, Tree
Date Inducted in National Collection: 07/09/1992

Description:

There are eleven taxa of Hibiscus endemic to Hawaii, seven taxa are threatened with extinction and one is extinct. Hibiscus arnottianus is known for its beautiful white fragrant flowers. There are three recognized subspecies of H. arnottianus on the islands of Hawaii, and the subspecies immaculatus, found only in four populations on the island of Molokai, is considered to be the rarest of the three. H. arnottianus subsp. immaculatus, a member of the hibiscus family (Malvaceae) is a tree up to three meters tall with alternate, oval, toothed leaves (5 to 7 cm long, 4 to 6.5 cm wide). The faintly fragrant flowers have white petals (8 to 11 cm long, 2.5 to 3.5 cm wide) with the calyx being 2.5 to 3 centimeters long. Anthers are arranged along the upper third of the white staminal column (10 to 14 cm long). This subspecies is distinguished from the other native Hawaiian members of its genus by its white petals and white staminal column (USFWS 1996).

Where is White Molokai Hibiscus (Hibiscus arnottianus ssp. immaculatus) located in the wild?

Habitat:

H. arnottianus subsp. immaculatus is found in mesic to wet forests at about 300 to 800 meters elevation (Wagner et al. 1999).

Distribution:

H. arnottianus subsp. immaculatus is restricted to the island of Molokai (Wailau, Waihanau, and Papalaua valleys) (USFWS 1996).

States & Provinces:

White Molokai Hibiscus can be found in Hawaii

Which CPC Partners conserve White Molokai Hibiscus (Hibiscus arnottianus ssp. immaculatus)?

National Tropical Botanical Garden

Conservation Actions

Nature Serve Biotics

05/02/2017

Endemic to the seacliffs along the north side of the island of Molokai. Currently, it is known from 2 occurrences with fewer than 100 plants. It is threatened by deer, feral pigs and goats, and alien plants.

01/01/2010

Threats to H. arnottianus subsp. immaculatus include the destruction of habitat by feral goats and potentially inbreeding resulting from a restricted genetic pool.

01/01/2010

Number of Populations: 4 (USFWS 2001) Number of Plants: <100 (USFWS 2001)

01/01/2010

The National Tropical Botanical Garden (NTBG) has propagated H. arnottianus subsp. immaculatus. No other conservation efforts have been undertaken.

01/01/2010

The Nature Conservancy of Hawaii (TNCH) is working with State and local hunters in remote sections of Kamakou and Pelekunu to try to reduce the population of feral goats. NTBG propagated H. arnottianus subsp. immaculatus and plans to research propagation methods and feasibility of long-term seed storage (USFWS 1996) NTBG currently has ex situ holdings of 190 seeds in its seed bank and three plants in the nursery of the botanical garden which represents one out of the four populations.

01/01/2010

1. Propagation and maintenance of ex situ genetic stock should be continued for H. arnottianus subsp. immaculatus. 2. Exclosures should be built for protection against feral goats. 3. Determine the best methods for ex situ propagation and transplanting also, a research program is recommended to study the growth and viability of H. arnottianus subsp. immaculatus. 4. Conduct pollination biology and reproductive studies. 5. Map genetic diversity in the surviving populations of H. arnottianus subsp. immaculatus. Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1996).

01/01/2010

1. Survey ex situ holdings and conduct molecular fingerprinting. 2. Establish secure ex situ stocks with full founder representation. 3. Develop proper horticultural protocols and pest management for H. arnottianus subsp. immaculatus. 4. Propagation and maintenance of ex situ genetic stock should be continued for H. arnottianus subsp. immaculatus. Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1996).