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Plant Profile

Kauai Hau Kuahiwi (Hibiscadelphus distans)

Closeup of mature flower. Photo Credit: National Tropical Botanical Garden

Global Rank: G1 - Critically Imperiled
Legal Status: Federally Endangered
Family: Malvaceae
State: HI
Nature Serve ID: 149384
Lifeform: Tree, Shrub
Date Inducted in National Collection: 02/10/1987

Description:

There are seven known species of Hibiscadelphus, which is a genus that is endemic to Hawaii. Five of those seven species are now extinct in the wild, although two of those are surviving in cultivation. H. distans is one of the two remaining Hibiscadelphus species with remaining wild populations. However, this species, too, is on the verge of extinction. In 2001, less than 200 individuals among two populations were recorded (USFWS 2001) and, as of 2002, this number had declined to just 30 plants in a single population (K. Wood, pers. comm. 2002). H. distans, a member of the hibiscus family (Malvaceae) is a shrub or small tree that grows up to 5 meters tall. Plants have a grayish brown trunk, graceful branching habit, and broadly ovate (heart-shaped) leaves. The upper surfaces of the leaves are sparsely pubescent with the under surface more densely pubescent (Wagner et. al., 1990). The greenish yellow tubular flowers of H. distans are erect and solitary, and turn maroon with age. Unlike many closely related members of the Hibiscus family, these flowers are bilaterally symmetrical. The seedpods are woody capsules with five sections containing seeds that are yellowish brown and pubescent (USFWS 1996).

Where is Kauai Hau Kuahiwi (Hibiscadelphus distans) located in the wild?

Habitat:

H. distans is found in dry forests at approximately 350 meters elevation. It is located above Koaie Stream on Kauai (Wagner et al. 1999).Associated species of H. distans include Aleurites moluccana (kukui), Artemisia kauaiensis (no common name [NCN]), Psydrax odoratum (alahee), Diospyros sandwicensis (lama), Lipochaeta connata (nehe), Myrsine sp. (kolea), Nototrichium sandwicense (kului), Pouteria sandwicense (alaa), Triumfetta semitriloba (Sacramento bur) and Sapindus oahuensis (lonomea). The ground cover is mostly alien grasses.

Distribution:

H. distans is endemic to Kauai. After hurricane Iniki a population of approximately 50 individuals was extirpated in Hipalau valley, one of only two sites where H. distans occur. The other known popul

States & Provinces:

Kauai Hau Kuahiwi can be found in Hawaii

Which CPC Partners conserve Kauai Hau Kuahiwi (Hibiscadelphus distans)?

National Tropical Botanical Garden

Not Sponsored

Assigned 06/09/17

Harold L. Lyon Arboretum

Not Sponsored

Assigned 07/24/23

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

Nature Serve Biotics

05/02/2017

This species has been found only in a small area in the Waimea Canyon, Kauai. Fewer than 200 plants are known to remain. The species' habitat is experiencing heavy degradation from the activities of feral goats and pigs. Alien plants are also a threat.

01/01/2010

Threats to H. distans include feral goats, alien plants such as Lantana camara (lantana), human disturbance, natural occurring events such as fires and hurricanes, insect pests such as the exotic pink bollworm (Pectinophora gossypiella), and potentially g

01/01/2010

Number of Populations: 1 recorded in 2002 Number of Plants: 30 recorded in 2002 (K. Wood, pers. comm. 2002)

01/01/2010

Seeds of H. distans have been tested by the National Seed Storage Laboratory (NSSL), and the National Tropical Botanical Garden (NTBG), finding that they are orthodox and can tolerate freezing and drying. The laboratory germination time was two months (Yoshinaga 2002).

01/01/2010

Seeds of H. distans are easily propagated if the seeds are available and undamaged. The USFWS has also conducted research on the pollinators of H. distans, finding that they may be capable of self-pollination. However, cross-pollination may be important for maintaining the species long term genetic variability (USFWS 1996). NTBG currently has ex situ holdings of seeds in its seed bank, there are 11 plants in the nursery and 48 individuals in the botanical garden. The 11 individuals represent the single population. The seeds and 48 plants in the botanical garden represent a population that was lost, in addition to the remaining population.

01/01/2010

1. Map genetic diversity in the surviving populations of H. distans. 2. Test the influence of weeding and fencing on populations of H. distans. 3. Conduct pollination biology and seed dispersal studies on H. distans. 4. Secure wild populations through on-site management. Recommendations derived from M.H. Chapin, and M. Maunder.

01/01/2010

1. Establish secure ex situ stocks with full founder representation. 2. Develop proper horticultural protocols and pest management for H. distans. 3. Survey ex situ holdings and conduct molecular fingerprinting. Recommendations derived from M.H. Chapin and M. Maunder.