Diamond Head Schiedea

Schiedea adamantis

Description

Diamond Head schiedea, Schiedea adamantis, is a low-growing, woody shrub with paired, narrow, parallel-veined leaves, which decrease in size toward the top of the plant. There are several species of Schiedea in the Hawaiian Islands, all with highly restricted distributions. Diamond Head schiedea possesses an unusual floral structure for its family, which has attracted scientific interest.

Habitat

Diamond Head schiedea is found in volcanic soils on the high windward slope and rim of Diamond Head Volcano.

Distribution

Diamond Head schiedea, discovered in 1955, has only been found on the island of Oahu, Hawaii. In-vading exotic plants and insects have degraded much of the habitat, crowding out native plants. In 1984, surveys located less than 80 mature individual shrubs. These occur in a concentrated population along the rim of Diamond Head crater, slightly below an existing hiking trail.

Threats

Diamond Head Volcano was heavily used by the military during the Second World War because of its strategic importance for protecting Honolulu. The construction of a communications facility on the northeast crest and defensive emplacements on the southern and western ridge summits of Diamond Head crater probably destroyed schiedea populations.

Hikers have become an increasing presence along the rim of Diamond Head, although certain portions of the rim trail have been placed off-limits because of safety considerations. Even so, soil in the immediate vicinity of the schiedea population has been compacted and denuded of vegetation by hikers. The state of Hawaii's plans to expand the recreational facilities and hiking trails on Diamond Head would funnel more traffic into the vicinity of the surviving shrubs, worsening soil compaction and increasing the risk of fire in the dry months between April and September.

Conservation and Recovery

Plans to expand the trail along the rim will need to consider the welfare of the schiedea. This might require rerouting proposed hiking trails or fencing the population site. The rim is already carefully monitored for brushfires during the dry season, and surveillance will be stepped up near the schiedea site. Additionally, a state program has been developed to control the spread of exotic plants on the volcano rim.

Contacts

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

Pacific Remote Islands Ecological Services Field Office
P.O. Box 50088
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-1201
Fax: (808) 541-1216

References

Fosberg, F. R., and D. Herbst. 1975. "Rare and Endangered Species of Hawaiian Vascular Plants." Allertonia 1(1):1-72.

Sohmer, S. H., and R. Gustafson. 1987. Plants and Flowers of Hawaii. University of Hawaii Press, Honolulu.

Takeuchi, W. 1980. "Status Report on Schiedea adamantis St. John." U.S. Fish and Wildlife Service, Honolulu.