Mehamehame

Flueggea neowawraea

Description

Flueggea neowawraea (commonly known as mehamehame; a member of the spurge family) is a large tree up to 100 ft (30.5 m) in height and 7 ft (2.1 m) in diameter with white oblong pores covering its scaly, pale brown bark. The thin, papery, oval leaves—1.5-5.5 in (3.8-14 cm) long and 0.8-3.5 in (2-8.9 cm) wide—are green on the upper surface and pale green on the lower surface. Plants are usually dioecious (the state of having separate male and female plants) with unisexual flowers lacking petals. Male flowers, on stalks less than 0.2 in (5.1 mm), have five green sepals with brownish tips. The female flowers, on stalks 0.04-0.1 in (1-2.5 mm) long, have sepals of unequal length with irregular margins. The two-lobed stigma is positioned atop a 0.1-in-long (2.5-mm-long) round ovary with a nectary disk. The round fruits, about 0.2 in (5.1 mm) in diameter, are fleshy, reddish-brown to black, and contain two slightly curved seeds about 0.1 in (2.5 mm) long that are somewhat triangular in cross section.

This species is the only member of the genus found in Hawaii, and it can be distinguished from other species in the genus by its large size; scaly bark; the shape, size, and color of the leaves; flowers clustered along the branches; and the size and shape of the fruits. Joseph F. Rock collected the first specimens of F. neowawraea from Kapua on the Big Island of Hawaii in 1912. The following year he established the monotypic genus Neowawraea from these collections, naming it for his colleague Dr. Heinrich W. Wawra. He named the species Neowawraea phyllanthoides because of its apparent resemblance to Phyllanthus, a fellow member of the spurge family. Earl Edward Sherff transferred the taxon to the genus Drypetes in 1939. W. John Hayden placed the species in the genus Flueggea in 1987.

Individual trees of F. neowawraea bear only male or female flowers and must be cross-pollinated from a different tree to produce viable seed. Little else is known about the life history of this species. Reproductive cycles, longevity, specific environmental requirements, and limiting factors are unknown.

Habitat

F. neowawraea occurs in dry to mesic forest at elevations of 820-3,280 ft (250-1,000 m). Associated plant species include alahe'e, lama, Aleurites moluccana (kukui), Antidesma pulvinatum (hame), and Streblus pendulina (a'ia'i).

Distribution

F. neowawraea was known historically from Waihii near Kapuna on Molokai, but it is now presumed extinct on that island. This species was also known 1) from Kealia Trail, Kahanahaiki Valley, and Pohakea Gulch in the Waianae Mountains of Oahu, 2) from Kauai, and 3) from the Big Island.

F. neowawraea currently has occurrences on Kauai, Oahu, East Maui, and the Big Island; the 34 statewide populations contained approximately 124-195 individuals in 1997.

Threats

The primary threat to the continued existence of F. neowawraea is the black twig borer (Xylosandrus compactus ), which has affected all known individuals of this species. Other major threats include habitat degradation by feral pigs, goats, deer, and cattle; competition with alien plant species; and fire. The small number of individuals within any population and the scattered distribution of populations, compounded by a requirement for cross-pollination because the species is dioecious, must be considered a serious threat.

The black twig borer has been cited as an immediate threat to all extant populations of F. neowawraea. This invasive alien insect burrows into the branches of this species, introducing a pathogenic fungus that prunes the host severely and often kills branches or whole plants. All known F. neowawraea individuals suffer slight to severe defoliation and reduced vigor due to black twig borer infestations.

Three populations of F. neowawraea on Kauai have lost individual plants and habitat as a result of feral pig activities, and 15 populations of this species on Oahu are threatened by pigs. Feral pigs are a major threat on the Big Island to one or more F. neowawraea populations in the regions of Manuka and Honomalino in the South Kona District.

Goats have contributed to the substantial decline of four populations of F. neowawraea on Kauai. Encroaching urbanization and hunting pressure on Oahu tend to concentrate the goat population in the dry upper slopes of the Waianae Mountains, where two populations of F. neowawraea exist. The goat population in the Waianae area, apparently on the rise, is becoming an even greater threat to the rare plants that grow there.

The F. neowawraea population in the Paaiki and Mahanaloa valleys on Kauai is threatened by the habitat-degrading activities of the black-tailed deer.

The East Maui population of this taxon, although growing within a fenced enclosure, continues to be potentially threatened by grazing cattle, since the cattle could possibly breach the barrier.

F. neowawraea is not known to be unpalatable to cattle, deer, and goats; as such, predation is a probable threat to this plant at sites where these animals have been reported.

All 15 populations of F. neowawraea that occur on Oahu have been damaged by Christmasberry. On the Big Island, Christmasberry continues to threaten at least two populations of F. neowawraea in the regions of Manuka and Honomalino in the South Kona District.

Strawberry guava poses an immediate threat to ten populations of F. neowawraea on Oahu. Koster's curse is widespread in Honouliuli and threatens two populations of the species that occur in that area of the Waianae Mountains on Oahu.

On Kauai, the growth of lantana, Australian red cedar, and Java plum pose threats to individuals of this endangered species.

Fire is a potential threat to two populations of F. neowawraea on Oahu located adjacent to Makua Military Reservation.

The reproductive system of F. neowawraea further exacerbates the problem of limited numbers for this species. Since each tree bears only male or female flowers, they must be cross-pollinated from a different tree. If only a few trees flower at the same time, or if flowering trees are too widely separated for pollination by insects, no seed will be set.

Conservation and Recovery

The U.S. Army Garrison's Five-Year Ecosystem Management Plans include actions to protect endangered species, prevent range fires, and minimize soil erosion. These actions should enhance conservation of the F. neowawraea plants growing on the Makua Military Reservation and Schofield Barracks Military Reservation.

One of the F. neowawraea plants on the U.S. Navy's Lualualei Naval Reservation has been fenced for protection from cattle and feral pigs. A program of alien plant removal within the enclosure is ongoing.

A long-range management plan for Honouliuli Preserve prescribes actions for alien plant management, ungulate control, fire control, small mammal control, rare species recovery, and native habitat restoration. These actions are expected to benefit F. neowawraea in the preserve.

As of 1997 the National Tropical Botanical Garden had more than 2,000 seeds in storage and 21 individuals in cultivation. Micropropagation has been attempted at Lyon Arboretum.

To prevent extinction of this gspecies, cultivated propagation should be tried again, even though prior attempts have been unsuccessful. Since most populations of F. neowawraea have only one or two remaining individuals, propagation material should be collected from these individuals immediately. Specific efforts should be made, when practicable, to hand-pollinate isolated populations.

Contacts

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
http://pacific.fws.gov/

Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-3441
Fax: (808) 541-3470

Reference

U. S. Fish and Wildlife Service. 10 November 1994. "Endangered Status for 12 Plants from the Hawaiian Islands." Federal Register 59 (217): 56333-56351.