Kamakahala

Labordia lydgatei

Description

Labordia lydgatei (kamakahala) is a much-branched shrub or small tree between 6.5-10 ft (2-3 m) in height with sparsely hairy, square stems. The opposite leaves with fine hairs on the lower surfaces and smooth upper surfaces are elliptic, often wider toward the tip, 2-4 in (5-10 cm) long, and 0.8-2.8 in (2-7 cm) wide. Intra-petiolar stipules are present. The inflorescences are produced at the ends of the stems and comprise 6-31 small, slender, and tubular pale yellow flowers 0.3 in (0.8 cm) long. Flower buds were collected in May, mature flowers in July, and green fruits in October. The fruit, a small ovoid capsule with a short blunt beak, splits into two valves at maturity to expose the seed mass. The small flowers and capsules borne on sessile inflorescences distinguish it from L. hirtella, L. sp. aff. hirtella, and L. tinifolia var. wahiawaensis, the other members of the genus growing in the vicinity. The small pale yellow flowers are presumably fragrant like those of related species and are probably insect-pollinated. Seeds of most species of Labordia are embedded in a fleshy orange, aril-like mass, which is presumably an adaptation for bird dispersal.

With only 23 known plants in three widely scattered areas, gene flow between these individuals is therefore unlikely. Immature fruits were seen on two of the plants and remnants of old fruiting bodies were seen on another, suggesting that the plants are self-fertile. Microhabitat requirements for seed germination and growth may be extremely specific. Virtually nothing is known about the life history or ecology of this species.

Habitat

Three collections of L. lydgatei were originally made in 1908 and 1909 by Lydgate and Forbes. Subsequent collections were made in 1987 and in 1988. At the time of listing, it was known from one population of about three plants located along one of the tributaries of the Wahiawa Stream at approximately 2,300 ft (701 m) elevation. The habitat in the upper Waioli Stream Valley below Namolokama Mountain at 1,300 ft (396 m) elevation consists of lowland rain forest with Metrosideros and Dicranopteris. This is similar to the L. lydgatei habitat in the Makaleha Mountains.

Distribution

L. lydgatei, the rarest of the Wahiawa species, has only 23 adult individuals known from four localities in the Wahiawa Drainage, the Waioli Stream Valley, and Makaleha Mountains. A juvenile possibly representing this species was seen, but it was not counted because identification was uncertain. Five of the adults were clearly referable to this species, but two other adults had flowers and leaves approximately 50% larger than normal for L. lydgatei and thus approach L. hirtella, H. Mann, a common species in the Wahiawa area and one that sets seed abundantly. The taxonomic status of these latter two plants needs to be investigated further. Of the three plants sighted in 1987 and in 1988, two were not relocated. The Waioli population consists of only two plants, and a single individual is known from the Makaleha Mountains.

Threats

The survival of the kamakahala is threatened by competition and habitat changes caused by invasive alien plants, the feeding activities of introduced mammalian herbivores, the possible loss of native pollinators, and the intrinsic risks of its tiny population size (only 23 individuals are known to survive).

Conservation and Recovery

The Fish and Wildlife Service published a Recovery Plan for the kamakahala and co-occurring endangered species in 1994. Its critical habitat is privately owned and is threatened by introduced plants and mammals and potentially by human activities. These habitats must be protected by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the owners. The critical habitat must be managed to reduce the threats posed by non-native plants, and to eradicate or reduce introduced mammals. The populations of the kamakahala should be monitored, and research undertaken into its biology, habitat needs, and the development of beneficial management practices. Research should be undertaken into captive propagation, even though attempts to cultivate other species of Labordia at Waimea Arboretum have failed.

Contacts

U.S. Fish and Wildlife Service
Pacific Islands Ecoregion
300 Ala Moana Boulevard, Room 3-122
Box 50088, Honolulu, Hawaii, 96850
Telephone: (808) 541-3441
Fax: (808) 541-3470

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

References

Cuddihy, L. W., and C.P. Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities and Introductions. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.

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

Stone, C.P., and J.M. Scott, eds. 1985. Hawai 'i's Terrestrial Ecosystems: Preservation and Management. Cooperative National park Resources Study Unit, University of Hawaii Press, Honolulu.

U.S. Fish and Wildlife Service. 1994. "Recovery Plan for the Wahiawa Plant Cluster: Cyanea undulata, Dubautia pauciflorula, Herperomannia lydgatei, Labordia lydgatei and Viola helenae." U.S. Fish and Wildlife Service, Portland, Oregon.

Wagner, W.L., D.R. Herbst, and S.H. Sohmer. 1990. Manual of the Flowering Plants of Hawai'i. University of Hawaii Press and Bishop Museum Press, Honolulu.