Alani

Melicope saint-johnii

Description

Melicope saint-johnii, a member of the citrus family (Rutaceae), is a slender tree 10-20 ft (3-6 m) tall. The leaves are opposite or occasionally occur in threes on young lateral branches; 2.4-6.3 in (6-16 cm) long and 1.2-3.3 in (3-8.4 cm) wide, the leaves are narrowly to broadly elliptic, sometimes elliptic egg-shaped, or rarely lance shaped. Three to 11 flowers are arranged on a flowering stalk 0.4-0.9 in (1-2.3 cm) long. The flowers are usually functionally unisexual, with staminate (male) and pistillate (female) flowers. The staminate flowers have broadly egg-shaped sepals that are hairless to sparsely covered with hair. The triangular petals, 0.2-0.3 in (5-7.5 mm) long, are densely covered with hair on the exterior. The pistillate flowers are similar in hairiness to staminate flowers, but are slightly smaller in size. The dry fruit, 0.3-0.5 in (7.5-13 mm) long, splits at maturity. The exocarp (outermost layer of the fruit wall) is hairless, whereas the endocarp (innermost layer) is hairy. This species is distinguished from others in the genus by the combination of the hairless exocarp, the hairy endocarp, the densely hairy petals, and the sparsely hairy to smooth sepals.

In 1944 E. P. Hume first described M. saint-johnii as Pelea saint-johnii from a specimen he collected with E. Christophersen and G. Wilder at Mauna Kapu on Oahu. Thomas Hartley and Benjamin Stone transferred Hawaiian Pelea species to the Pacific genus Melicope in 1989, resulting in the new combination M. saint-johnii. Other published names that refer to this plant are Evodia elliptica var. elongata, Pelea elliptica var. elongata, P. elongata, and P. saint-johnii var. elongata.

Habitat

M. saint-johnii typically grows on mesic forest ridges at elevations of 1,640-2,800 ft (500-850 m). Associated native plant taxa include mamaki, 'ohi'a, pilo, kopa, kamakahala, and kopiko.

Distribution

M. saint-johnii was known historically from both the Waianae and Koolau Mountains—Makaha to Mauna Kapu in the Waianae Mountains and Papali Gulch in Hauula, Manoa-Aihualama, Wailupe, and Niu Valley in the Koolau Mountains. Eight populations of this species are now found on federal (Lualualei Naval Reservation), state, and private land from the region between Puu Kaua and Puu Kane-hoa to Mauna Kapu in the southern Waianae Mountains. Less than 150 individuals of this species were known in 1997; at least three populations contained only one individual.

Threats

The primary threats to M. saint-johnii are habitat degradation and destruction by feral goats and pigs; potential predation by the black twig borer; potential fire; and competition with alien plants such as Christmasberry, firetree, Hamakua pamakani, huehue haole, lantana, Maui pamakani, and silk oak.

The largest population of this species is directly threatened by feral goat trampling of plants and seedlings, as well as by goat-induced substrate erosion. M. saint-johnii is not known to be unpalatable to goats and grows in areas where they have been reported; direct predation is therefore a possible threat.

The black twig borer occurs throughout the Waianae Mountains and threatens almost all M. saint-johnii plants that occur there.

Christmasberry grows in dense thickets that threaten this species. The mat-forming weed Hamakua pamakani and silk oak are threats to M. saint-johnii. Lantana, a thicket-forming shrub, also threatens this endangered species; the smothering vine Huehue haole and firetree are additional threats.

Accidentally or maliciously set fires in inhabited areas near the Lualualei Naval Reservation and the Makua Military Reservation could easily spread and pose a possible threat to one population of M. saint-johnii.

Conservation and Recovery

The Palawai population is within the boundaries of a fenced enclosure that the Nature Conservancy of Hawaii built in 1998.

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