Alsinidendron trinerve

No Common Name

Description

Alsinidendron trinerve is a small, branching shrub of the pink family that grows to 3 ft (0.9 m). The thick, somewhat fleshy leaves are elliptical, 1.6-4.3 in (4-10.9 cm) long, and possess three or five large veins. The flowers, borne in open dusters of 7-12, lack petals, but have five sepals that are white on the inside and green or green-veined on the outside. In fruit, these sepals turn purple and become fleshy, forming a structure resembling a berry. A. trinerve differs from A. obovatum, a closely related endangered plant also from Oahu, in having more open flower clusters, longer flower stalks, sepals with an acute rather than a rounded tip, and a different habitat.

Habitat

A. trinerve grows in the Waianae Mountains on slopes in wet forest dominated by ohia (Metrosideros polymorpha) and kawau (Ilex anomala) at elevations between 3,000 and 4,000 ft (914 and 1219 m). Associated plant species include pilo (Coprosma ochracea), 'ape'ape (Gunhera), and alani (Melicope sandwicensis).

Distribution

A. trinerve is a locally evolved (or endemic) species that only occurs on the island of Oahu, in the Hawaiian archipelago. Historically, it is known from the north-central and southern regions of the Maianae Mountains. In the mid-1990s, it was only known to survive as three small montane populations on Mount Kaala and Puu Kalena.

Threats

The major threats to A. trinerve are competition from an alien plant species and habitat degradation by feral pigs. A. trinerve is directly threatened by prickly Florida blackberry.

Conservation and Recovery

Forty to 45 individuals of A. trinerve were out-planted in a fenced and managed area in the Mt. Kaala National Area Reserve in September 1996. However, these plants are not doing well, probably due to oversaturation and low pH in the soil. There are more than 300 seedlings growing at the mid-elevation nursery at the Nike missile site.

The Nature Conservancy of Hawaii examined the Mt. Kaala population of A. trinerve to determine management needs. Although the plants are threatened by feral pigs, The Nature Conservancy of Hawaii determined that a small fence around the population would increase open trampled areas that attract pigs and create sites for weeds to become established. Fencing of individual populations is also not feasible because of the steep slopes. Strategic fencing of a larger area should be considered and general feral pig control measures need to be implemented. In areas where fencing is not feasible, snaring for ungulate control should be judiciously used.

Specific efforts should be made immediately to weed and protect the three extant populations. Manual removal will be difficult at all sites and may harm populations by opening corridors for feral pigs. Any weeding should be done with care, and biocontrol options for prickly Florida blackberry need to be explored.

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/

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

References

U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Oahu Plants." U.S. Fish and Wildlife Service, Portland, Oregon. 207 pp., plus appendices.

U.S. Fish and Wildlife Service. 1998. "Recovery Plant for the Oahu Plants." http://endangered.fws.gov/recovery/recplans/