Endangered Species in the Pacific Islands
Recovery Plan for Hibiscadelphus distans
||Hibiscadelphus distans is one of the world's rarest trees and can only be found on the island of Kaua‘i. It is a shrub or small tree up to 18 feet tall with smooth bark and a rounded crown.
The Hawaiian name for this tree is "hau kuahiwi" which means upland or mountain "hau" because of its resemblance to the common lowland Hibiscus tiliaceus.
There are only two known naturally occurring populations with an estimated total of of 20 trees. Approximately 150 individuals have been reintroduced and are reproducing.
Hibiscadelphus distans - Photo credit
Dr. Carr/University of Hawaii
Habitat & Distribution:
H. distansis is found in low to mid-elevations, between 1,000 to 1,800 feet in highly degraded native dryland forests that receive full sun in summer with no direct sun in winter. The substrate is basaltic bedrock overlain by dry, crumbly red-brown soil.
The original population, found in 1972, was located within the State-owned Na Pali Kona Forest Reserve, Koaie Canyon. In 1989, this population was destroyed by a landslide. There are an estimated total of 20 wild and 150 reintroduced trees today.
All remaining H. distans are threatened by alien plant competitors, introduced herbivores (goats and insects), human disturbances, rockslides, catastrophic events, and a limited gene pool. H. distansare included in and managed as Conservation District Forest Land, under the jurisdiction of the State Division of Forestry and Wildlife.
DOFAW has constructed enclosures around naturally occurring plants that require protection from feral goat browsing and has undertaken a program of outplanting of propagated seedlings into exclosure sites. Exclusion of the goats, weeding, watering, and fertilizing have in a short time resulted in the regeneration of H. distans in the Lower Koaie Canyon area.
Several botanical gardens in Hawai‘i have cultivated this plant species. To achieve recovery of H. distans, steps to control and minimize the threats acting upon the existing populations must be undertaken. At
the same time, surveys within likely habitat areas in Waimea Canyon must be carried out to determine whether any other populations currently exist, and all newly discovered populations must be adequately protected.