Alsinidendron Obovatum

views updated

Alsinidendron obovatum

No Common Name

ListedOctober 29, 1991
FamilyCaryophyllaceae (Pink)
DescriptionSmall shrub with thick, elliptic leaves and dense clusters of flowers, lacking petals but having five white and green sepals.
HabitatRidges and slopes in lowland moist forest.
ThreatsAlien plant species, feral pigs, low numbers.


Alsinidendron obovatum is a small branching shrub of the pink family that grows to 3 ft (0.9 m) in height. The thick, somewhat fleshy leaves are elliptic, 1.6-4.3 in (4.1-10.9 cm) long, and have three or five large veins. The flowers lack petals but have five sepals that are white on the inside and green or green-veined on the outside. They are borne in dense clusters of seven to 12. In fruit, the sepals turn purple and become fleshy, forming a structure resembling a berry.

A. obovatum differs from A. trinerve, a closely related endangered plant from Oahu, in having more closed flower clusters, shorter flower stalks, sepals with a rounded rather than an acute tip, and a different habitat.

A. obovatum generally flowers after about two years of growth. Plants flower and fruit year-round, but flowering is usually heavier in winter and spring depending upon precipitation. Plants survive to six years unless there are drought conditions.


A. obovatum grows on ridges and slopes of the Waianae Mountain Range in lowland moist forest dominated by koa (Acacia koa ) and 'ohi'a (Metrosiderospolymorpha ) at elevations of 1,850-2,500 ft (548.6-762 m). Associated plant species include ko'oko'olau (Bidens ) and Java plum (Syzgium comini ).


A. obovatum was first collected in 1911. It has been found only along the northern and southern ends of the Waianae Mountains.

The four known populations contain 12 individuals: eight in Kapuna Gulch, one and two at two sites in Pahole Gulch, and one in Kahanahaiki within Makua Military Reservation. The first two occurrences are on state land; the last one is on U.S. Army land.


The major threats to A. obovatum are competition from molasses grass (Melinus minutifiora ), an aggressive non-native species, and habitat degradation by feral pigs. Molasses grass, which ranges from the dry lowlands to the lower wet forests of the leeward ridges, grows in dense mats that smother native vegetation.

The low number of known plants and their limited distribution make the species vulnerable to extinction through unpredictable human or natural events. Some plants are located near hiking trails and are exposed to trampling.

Conservation and Recovery

Eight individuals have been planted in an enclosure at Pahole National Area Reserve. Approximately 40 individuals are also retained at the Division of Forestry and Wildlife's mid-elevation propagation facility in the Waianae Mountains (a Nike missile site), where they have grown to maturity. These plants have been crossed, and fruit has been collected from the crosses. In addition, the species is being propagated at the National Tropical Botanical Garden and the Lyon Arboretum.

The army has adopted a fire management plan that includes realigning targets and establishing firebreaks. These actions may aid in protecting A. obovatum from the threat of fire. The one individual occurring on Makua Military Reservation has been included in a large fenced enclosure from which ungulates have been eradicated. This species is targeted for outplanting within the existing enclosure.


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

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


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. Hawaii's Terrestrial Ecosystems: Preservation and Management. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.