Alani

Melicope balloui

Description

Melicope balloui is a small tree or shrub of the citrus family (Rutaceae), the new growth of which has yellowish-brown woolly hairs and waxy scales. Plant parts later become nearly hairless. Leaves are opposite, leathery, inversely ovate to elliptic, 2-3.9 in (5-10 cm) long, 1.2-2.8 in (3-7 cm) wide, and have petioles 0.4-1 in (1-2.5 cm) long. The upper and lower surfaces of mature leaves are hairless except along the midrib of the lower surface. Each flower cluster is on a main stalk 0.1-0.6 in (2.5-15 mm) long and comprises five to nine flowers on individual stalks about 0.2 in (5 mm) long. Only female flowers have been observed, and each consists of four sepals about 0.1 in (2.5 mm) long, four petals about 0.2 in (5 mm) long, an eight-lobed nectary disk, eight reduced and nonfunctional stamens, and a four-celled ovary with many short, fine hairs. The fruit, a four-lobed capsule 1-1.1 in (2.5-2.8 cm) wide, consists of 0.5-in (1.3-cm) long carpels fused about a quarter of their length. Sepals and petals usually remain attached to the mature fruit. One or two glossy black seeds about 0.3 in (7.5 mm) long are found in each fertile carpel. The exocarp and endocarp are covered with fine, short hairs. M. balloui is distinguished from other species of the genus by the partially fused carpels of its four-lobed capsule and the usually persistent sepals and petals.

Habitat

This species typically grows in koa-and 'ohi'a-dominated montane wet forests at elevations of 4,200-5,000 ft (1,280-1,520 m). Associated species include Coprosma sp. (pilo), Dicranopteris linearis (uluhe), Joinvillea ascendens ssp. ascendens ('ohe), and Peperomia subpetiolata ('ala'ala wai nui).

Distribution

M. balloui, found only on the northern and southeastern slopes of Haleakala on the Hawaiian island of Maui, is a rare plant whose last of nine collections, before its late twentieth-century rediscovery, were made in 1927. This disjunct distribution of M. balloui was discovered in 1988 in Kipahulu Valley, part of Haleakala National Park, based on a specimen collected at an elevation of about 2,500 ft (760 m). M. balloui is now known to be rare at elevations of 2,200-3,300 ft (670-1,000 m) in mixed Acacia koa and Metrosideros polymorpha forests in the Kipahulu Valley. Based on available information, there appear to be less than 300 extant individuals.

Threats

Feral pigs are currently being controlled in Haleakala National Park. Constant vigilance is required to keep fences repaired and to remove pigs that get in through breaks in the fence. If uncontrolled, Hilo grass, Koster's curse, strawberry guava, kahili ginger, and Australian tree fern represent potential serious threats to the long-term survival of M. balloui. The endemic microlepidopteran is known to feed on the buds, flowers, and seeds of Melicope and Platydesma.

Conservation and Recovery

M. balloui has been successfully propagated at the Lyon Arboretum on Oahu. Protection of the Kipahulu Valley ecosystem by Haleakala National Park through construction of barrier fences, pig removal, and alien plant management provided a major action toward recovery of this species before its listing.

Further recovery actions that need to be implemented include maintaining relatively pig-free conditions in the Kipahula Valley at Haleakala National Park; continuing alien plant control in the same valley, with emphasis on Clidemia hirta, Cyathea cooperi, Hedychiurn gardnerianum, and Psidium cattleianum; producing an accurate assessment of population numbers and distribution; and establishing simple baseline monitoring of known individuals.

There has been little accurate information to date regarding population size and distribution of this species. Field work by trained resource management and research workers in Kipahulu over several years would allow this type of assessment. More accurate assessment of populations of this species will allow meaningful assessment of conservation potential and management needs.

There is a very good chance that this species still exists in the habitat where it was first discovered somewhere in the middle elevation forests of northwest Haleakala. Two reasons for the lack of modern collections of this species from that region may be the lack of sufficient modern biological exploration of the area due to the generally closed access maintained by Haleakala Ranch, East Maui Irrigation, and the State of Hawaii's Division of Forestry and Wildlife; and the cryptic nature of the species. With casual observation, M. balloui is easily confused with the more common and widespread M. volcanica and M. molokaiensis, both of which can be sympatric. Fruit characters, often unavailable, are the primary determinant used to separate M. balloui from these other two species.

The degree of damage from insect predation needs to be investigated and remedied, if needed. Rodents do not seem to be an important limiting factor for M. balloui as they are for M. ovalis, which grows adjacent to M. balloui. There may be as yet undetermined factors that have contributed to the rarity of M. balloui.

Contact

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/

Reference

U. S. Fish and Wildlife Service. 1997. "Recovery Plan for the Maui Plant Cluster." U. S. Fish and Wildlife Service, Portland, Oregon, 130 pp.