views updated


Hedyotis coriacea

ListedMay 15, 1992
FamilyRubiaceae (Coffee)
DescriptionSmall branched shrub with leatheryleaves and flowers that cluster at theend of branches.
HabitatSteep, rocky slopes in dry to mesic 'a'ali'i-dominated shrublands or forests.
ThreatsLimited numbers; extirpation by fire.


Kio'ele (Hedyotis coriacea ), a small shrub in the coffee family, has leathery leaves that are generally elliptic to oblong in shape, 1.2-3.2 in (3-8.1 cm) long, and 0.6-1.2 in (1.5-3 cm) wide. The clustered flowers are located at the ends of the branches and consist of a few flowers per cluster. The petals are fleshy and fused into a 0.2-0.4-in-long (5.1-10.2-mm-long) tube. The capsules, which split open to release several dark brown seeds, are shaped like a cup or a top.


H. coriacea is found on steep, rocky slopes in dry to mesic 'a'ali'i-dominated shrublands or forests at an elevation of 1,560-7,500 ft (475.5-2,286 m). Associated plants species include 'ohi'a, pukiawe, maile, ko'oko'olau, and Gouania. The vegetation communities in which this species grows thrive on rich soil and high rainfall totals of 100 in (254 cm) annually traits that lead to a high diversity of plants with an abundant understory.


Historically, H. coriacea was known from the Waianae and Koolau Mountains on Oahu and Pohakuloa Training Area on the Big Island of Hawaii. This species has not been seen for many years on Oahu.

Considered extinct since the 1940s, this species was rediscovered in 1990 in the West Maui Natural Area Reserve. In 1991 two individuals were found on the island of Hawaii on the 1859 lava flow in the Pohakuloa Training Area. Several more plants were subsequently discovered in this area, making it the only known natural occurrence of more than a single individual. There were about 17 individuals on Hawaii and a single plant on West Maui in 1995.


The very small remaining number of individuals of H. coriacea and the limited and scattered distribution of the species are threats since a single natural or human-caused environmental disturbance could easily be catastrophic to the few surviving plants on each island. In addition, the limited gene pool may depress reproductive vigor.

The possibility of fire is a major threat to the existence of H. coriacea, particularly in view of the small remaining numbers of this species. Natural fires, fires set accidentally by hunters, and fires started by military ordnance or service personnel within Pohakuloa Training Area threaten native vegetation on the leeward side of Mauna Kea, including the habitat of the remnant individuals of H. coriacea. Habitat disturbance caused by military exercises at Pohakuloa Training Area may have threatened H. coriacea in the past. Planned military activities are now being reevaluated in light of the recent discovery of several endangered plants in the area.

The alien plant fountain grass is a particular threat to the Pohakuloa Training Area population of this species.

Illegal collecting for scientific or horticultural purposes or excessive visits by individuals interested in seeing rare plants could result from increased publicity and would seriously threaten H. coriacea. Because of the few remaining individuals in existence, any collection of whole plants or reproductive parts would further diminish the gene pool and threaten the survival of this species. Hikers may inadvertently cause disturbance to the West Maui habitat.

Conservation and Recovery

H. coriacea has been propagated at the National Tropical Botanical Garden and at the Division of Forestry and Wildlife nursery on Maui. Planned military activities are presently being reevaluated in light of the recent discovery of several endangered plants on Pohakuloa Training Area.

Successfully establishing additional H. coriacea populations and then managing them with judicious fencing and weed control would provide the species with its best protection against stochastic extinction caused by fire or other destructive natural events. New populations should be located in areas far enough away from existing populations that the same wildfire could not destroy both natural and introduced occurrences.

The H. coriacea population at Pohakuloa Training Area needs protection from surrounding alien plants through the construction of an enclosure; in conjunction with this, a thorough monitoring program needs to be established.

This species often occurs in lower-to middle-elevation areas where alien ants are dominant and have caused the loss of most native Hawaiian insects. It is important to determine what kind and how many native pollinators remain and whether the species is self-incompatible, that is, whether pollinators are a limiting factor in its reproductive biology.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121

Pacific Remote Islands Ecological Services Field
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-1201
Fax: (808) 541-1216


Culliney, J. 1988. Islands in a Far Sea: Nature and Man in Hawaii. Sierra Club Books, San Francisco. 410 pp.

Soil Conservation Service. 1972. Soil Survey of Islands of Kauai, Oahu, Maui, Molokai, and Lanai, State of Hawaii. Soil Conservation Service, 232 pp.

Soil Conservation Service. 1981. Land Resource Regions and Major Land Resource Areas of the United States. Soil Conservation Service, 156 pp.

U. S. Fish and Wildlife Service. 15 May 1992. "Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for 15 Plants from the Island of Maui, Hawaii." Federal Register 57 (95): 20772-20787.