Abutilon eremitopetalum

No Common Name

Description

Abutilon eremitopetalum, a shrub in the mallow family (Malvaceae), has grayish-green, densely hairy, heart-shaped leaves that are 2.7-4.7 in (6.9-11.9 cm) long. One or two flowers are on stems up to 1.6 in (4.1 cm) long in the leaf axils. The calyx of the flowers is green, cup-shaped, and about 0.6 in (1.5 cm) long. The petals are shorter than the calyx and are bright green on the upper surface and reddish on the lower surface. The staminal column extends beyond the calyx and is white to yellow, with red style branches tipped with green stigmas. The fruit is a hairy, brown, dry, cylindrical capsule about 0.4 in (1 cm) long. It is the only Abutilon on Lanai whose flowers have green petals hidden within the calyx. A. eremitopetalum apparently flowers during the wet season in February.

Habitat

The habitat of A. eremitopetalum is within the lowland dry forest zone. The only known population occurs at an elevation of 1,100 ft (335.3 m) on a moderately steep north-facing slope on Lanai. The substrate is red sandy soil and rock. A. eremitopetalum has been historically reported from elevations of 690-1,710 ft (210.3-521.2 m). Erythrina sandwicensis and Diospyros ferrea are the dominant trees in open forest of the area. Other associated native plants include Canthium odoratum, Dodonaea viscosa, Nesoluma polynesicum, Rauvolfia sandwicensis, Sida fallax, and Wikstroemia sp. Associated alien plants include lantana, koa haole, and Pluchea.

Distribution

A. eremitopetalum is endemic to dry forest habitats of Lanai. Always very rare since its discovery in the 1930s, A. eremitopetalum has been known only in small and widely scattered colonies. It has been recorded across the northern slope of the island in a northwest to northeast line from Ka'a, Mahana, Maunalei, Kalulu, and Pawili. Individuals of A. eremitopetalum, at least some from Kalulu, were introduced to the dry forest area of Kanepu'u in the 1920s-30s and may have grown there in a naturalized state. Reproducing populations were found in the Maunalei area in 1930, but only two or three plants were found there in 1951. By the early 1980s the species was generally considered extinct.

About 60-70 plants were discovered in 1987 on a slope in Kahea Gulch (north fork) at elevations of between 790-1,050 ft (241-320 m). In June 1989, 70 plants were observed in this same population. Eleven years later only 30 plants, some with flowers or fruit, were noted. By June 1993, all but seven had been killed by deer.

Threats

Competition from encroaching exotic plant species, especially lantana, poses by far the greatest threat. Koa haole and sourbush are also present.

Browsing by axis deer is another significant threat, although A. eremitopetalum does not appear to be a preferred food of the deer. Deer will browse the species if other food sources become scarce. With only seven plants surviving, browsing could rapidly damage the few individuals left, and trampling could significantly affect the survival of seedlings. However, deer also have the positive effect of browsing alien invaders. The tradeoffs are not entirely clear in this case, and care must be taken—if the A. eremitopetalum population is fenced from deer—that alien plants are not allowed to overwhelm the endangered species. Timely management will be required.

Fire is a potential threat because the area is dry much of the year. A. eremitopetalum grows on lower elevations in dry ridges where fires are known to occur.

With only seven individuals in a single population, the limited gene pool may depress reproductive vigor. Whether or not genetic limitations pose a problem, any natural or human-caused environmental disturbance could destroy the only known population.

Because native insects may have been the pollinators of A. eremitopetalum, the probable loss of appropriate pollinators is very likely to pose an additional threat. Invasion by alien weeds, drought, and mismanagement of the population are also particularly critical potential threats to the survival of the species. Management tactics must be well thought out and closely monitored to ensure that they do not jeopardize the population in unexpected ways.

Conservation and Recovery

A. eremitopetalum is currently cultivated at the Hawaii State Department of Land and Natural Resources baseyard on Maui and at National Tropical Botanical Garden. Before A. eremitopetalum 's listing as federally endangered, progeny of those plants had been distributed to other individuals for cultivation. The Hawaii Plant Conservation Center collected seed from A. eremitopetalum in May 1990.

A. eremitopetalum is represented in the National Tropical Botanical Garden, the Waimea Arboretum and Botanical Garden, and the Amy Greenwell Ethnobotanical Garden. Hawaii Plant Conservation Center had approximately 3,000 seeds of A. eremitopetalum in storage as of August 1992 and has 14 plants in cultivation.

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
(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) 541-1201
Fax: (808) 541-1216

References

Bates, D. M. 1990. "Malvaceae." In Manual of the Flowering Plants of Hawaii, by W. L. Wagner, D. R. Herbst, and S. H. Sohmer. University of Hawaii Press and Bishop Museum Press, Honolulu.

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.