Maui Remya

Remya mauiensis

Description

Maui Remya, Remya mauiensis, is a sprawling, many-branched shrub in the aster family (Asteraceae or Compositae). Plants grow to between 3 and 6 ft (0.9 and 1.8 m) in height and form loosely tangled clumps that sprawl on or among the branches of other vegetation. Branches are ascending and densely leafy along the new growth, the young parts with dense whitish hair. The leaves are papery and narrowly oval-shaped with forward-pointing teeth on the margins. Leaf stalks (petioles) are 0.4 in (1 cm) long. The upper leaf surfaces have long, tangled hairs when young, becoming less dense when older; the lower surfaces have grayish-white tangled hairs. Flower heads occur in dense, woolly clusters on short stalks; the tiny, cream-colored flower heads are comprised of both ray and minute disk florets. The fruits are small and dry achenes. R. mauiensis can be distinguished from R. kauaiensis because the leaves are much longer relative to their width than those of R. kauaiensis.

Habitat

R. mauiensis grows chiefly on steep, north-or northeast-facing slopes at 2,790-4,100 ft (850.4-1,249.7 m) in elevation and is found primarily in mixed mesophytic forests or the remnants of such forests. Associated native species include Diospyros sandwicensis, Metrosideros polymorpha, Xylosma hawaiiense, Nestegis sandwicensis, Mysine, Wikstroemia, Dodonaea viscosa, Diplazium sandwichianum, Lysimachia remyi, Melicope spp., Alyxia oliviformis, Pleomele auwahiensis, and Styphelia tameiameiae.

Distribution

R. mauiensis has apparently never been common during historical times. Wilhelm Hillebrand collected R. mauiensis twice in the 1800s, and it was collected once in 1920; all of these collections were from West Maui. The species was thought to be extinct until its rediscovery in 1971 on the slopes of Manawainui Gulch on West Maui. It has since also been found in an adjacent gulch. While all potential habitat has not been searched for R. mauiensis, the results of botanical exploration of the region have demonstrated that this species is extremely rare. Because of the often dense growth of surrounding vegetation, it is difficult to determine the exact number of R. mauiensis individuals in a population. This species is known from two small populations occupying less than 2.4 acres (0.96 hectares) of state-owned land on adjacent ridges on West Maui. In 1990 there appeared to be seven plants in one population and two in the other.

Threats

R. mauiensis occurs in a mostly dry, fire-prone area, where brush fires set accidentally or intentionally could extirpate the species.

Browsing, grazing, and trampling by feral and domesticated livestock have harmed R. mauiensis and its habitat through direct destruction of plants and indirect degradation of the soil caused by grazing-induced loss of vegetation. It is clear that habitat well-suited for R. mauiensis within its former range was likely destroyed or degraded by cattle, goats, and pigs, and that the remaining extant individuals are found growing only in areas relatively inaccessible to these animals. Historically, the primary threats to this species likely include the impacts of feral ungulates, fire, and competition with alien plant species.

Browsing and associated habitat disturbance caused by hoofed mammals have favored the invasion and spread of numerous aggressive, alien plants that may compete for space, light, water, and nutrients with this listed species. Such alien species have replaced R. mauiensis throughout its presumed former habitat. Competition from alien plants may also be the reason for the low number of R. mauiensis in areas such as Manawainui Plant Sanctuary, where populations have been protected from ungulates.

The very small remaining number of individuals of R. mauiensis and their limited and scattered distribution are threats since a single natural or human-caused environmental disturbance could easily be catastrophic to the species. The limited gene pool may also depress reproductive vigor.

As these plants grow mostly on steep slopes, visits to the area by individuals wishing to see or photograph a rare plant could result in increased erosion. Illegal collecting for scientific or horticultural purposes or excessive visits by individuals interested in seeing rare plants could result from increased publicity with deleterious effects on the species.

Conservation and Recovery

All known individuals of R. mauiensis grow on state-owned land within the woven wire exclosure of the 56-acre (22.4-hectare) Manawainui Plant Sanctuary, built and maintained by Maui Division of Forestry and Wildlife. Current state regulations prohibit the removal, destruction, or damage of plants.

R. mauiensis has been successfully propagated at National Tropical Botanic Gardens on Kauai. National Tropical Botanic Gardens had 3,250 seeds in storage as of February 1993.

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/

Senior Resident Agent Office
U.S. Fish and Wildlife Service
300 Ala Moana Boulevard, Room 7-235
P.O. Box 50223
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-2681
Fax: (808) 541-3062

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, Honolulu.

Herbst, D. R. 1988. "Status Survey of the Genus Remya." U.S. Fish and Wildlife Service, Honolulu.

Wagner, W. L., and D. R. Herbst. 1987. "A New Species of Remya (Asteraceae: Astereae) on Kaua'i and a Review of the Genus." Systematic Botany 12(4): 601-608.

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.