Bonamia menziesii

No Common Name

Description

Bonamia menziesii, a member of the morning-glory family, is a vine with twining branches up to 33 ft (10.1 m) long that are fuzzy when young. The leathery, oblong to oval leaves measure 1.2-3.5 in (3-8.9 cm) in length and 0.4-1.6 in (1-4.1 cm) in width. The upper leaf surface is usually hairless or covered with sparse hairs, and the lower surface is covered with dense fuzzy hairs. The white to greenish funnel-shaped flowers, each 0.08-0.1 in (2-2.5 mm) long, are produced singly or in clusters of three on stalks 0.4-0.8 in (1-2 cm) long with tiny bracts (modified leaves) at the base of each stalk. Stamens usually have glandular hairs at their bases. The flower has two styles that are separate or partly fused. The fruits are tan or yellowish-brown capsules 0.4-0.6 in (1-1.5 cm) long that contain one or two oval seeds embedded in black pulp.

This species is the only member of the genus that is endemic to the Hawaiian Islands, and it differs from other genera in the family by its two styles, longer stems and petioles, and rounder leaves.

Asa Gray named B. menziesii in 1862 after Archibald Menzies, who first collected the plant from the Sandwich Islands (Hawaii). Wilhelm Hille-brand placed the species into the segregate genus Breweria in 1888. Then, in 1932, Otto Degener described the new genus Perispermum, placed B. menziesii in it, and also described P. albiflorum, another species of Perispermum. In 1968, T. Myint and D.B. Ward recognized only one Hawaiian species, which they placed in the genus Bonamia, and two varieties—variety menziesii and a new variety, rockii. The current treatment by Austin in 1990 recognizes only one species with no subspecific designations.

Habitat

B. menziesii is found on steep slopes in dry to mesic forest and sometimes in wet forest at elevations of 492-2,051 ft (150-625 m). Associated species include 'ohi'a, Canthium odoratum (alahe'e), Nestegis sandwicense (olopua), Pisonia sp. (papala kepau), and Sapindus oahuensis (lonomea).

Distribution

B. menziesii had historical occurrences on scattered locations on Kauai, the Waianae Mountains of Oahu, scattered locations on Molokai, one location on West Maui, and the eastern part of the island of Hawaii.

B. menziesii was known in 1997 from 31-44 populations on five islands. The total population throughout the state of Hawaii consisted of several thousand individuals, with the largest populations occurring on Kauai. Several thousand plants occurred on Kauai, no more than 150 on Oahu, about 12 on Lanai, 10-15 on Maui, and at least one on the Big Island of Hawaii.

Threats

The primary threats to B. menziesii are habitat degradation and possible predation by feral and wild pigs, goats, axis deer, black-tailed deer, and cattle; competition with a variety of alien plant species; and fire.

Four populations of the plant on Oahu are threatened by the habitat degrading activities of pigs. In addition, encroaching urbanization and hunting pressure on Oahu tend to concentrate the threatening goat population in the dry upper slopes of the Waianae Mountains, where one population of this species exists. The goat population in the Waianae area is apparently increasing, becoming an even greater threat to the rare plants that grow there. On Kauai, goats have contributed to the substantial decline of one population of B. menziesii.

The habitat of three Lanai populations of B. menziesii have been damaged by axis deer. The Nature Conservancy of Hawaii is erecting fences to help protect two populations of this plant that occur within Kanepuu Preserve from the degradations of axis deer. The fencing in place is normally high enough to prevent deer entry, but human pressure can force the deer to jump over the barrier. On Kauai, one population of B. menziesii in Paaiki Valley is threatened by black-tailed deer.

One population of this plant in Lualualei in the Waianae Mountains of Oahu is potentially threatened by cattle grazing. Populations of B. menziesii on both East and West Maui continue to be potentially threatened by cattle. One of these populations grows within a fenced enclosure, but the possibility of cattle entering the enclosure cannot be discounted. The only known population of B. menziesii on the island of Hawaii grows in a region currently used for cattle ranching.

Plants of this species at Lualualei on Oahu grow over native vegetation and drape well below the browse line of cattle, indicating the potential for these ungulates to feed on the plants.

More than half of the populations of B. menziesii on Oahu and one population of this species on Lanai have been damaged by Christmasberry. Christmas-berry is spreading on East Maui in Iao Valley and on the south slope of Haleakala Volcano, proving in both places to be one of the primary alien plant threats to populations of B. menziesii.

Strawberry guava is a direct threat to at least one population of this listed plant on Kauai, poses an immediate threat to six populations on Oahu, and is beginning to invade the habitat of one population on West Maui.

Three populations of B. menziesii in the Waianae Mountains of Oahu are immediately threatened by molasses grass. Fountain grass threatens the native vegetation on the leeward slopes of Hualalai in a region where the only known Hawaii Island population of B. menziesii exists.

One population of the plant on Lanai and one population on Maui are threatened by lantana. In the Waianae Mountains of Oahu, koa haole is one of the primary weed threats to half of the B. menziesii populations. Australian red cedar poses a definite threat to at least one population of this plant in the Waianae Mountains.

On Oahu, fire is a potential threat to three populations of B. menziesii located adjacent to Makua Military Reservation, where ordnance training exercises could unintentionally ignite fires. The area has had a history of fires that may have burned through at least one of the B. menziesii populations and burned to within a few tens of meters (about a hundred feet) of another. Fire is also a threat to one population of this species on Lanai.

Conservation and Recovery

The U.S. Army Garrison's five-year Ecosystem Management Plan is expected to enhance conservation of the B. menziesii plants found on the Makua Military Reservation. In addition, the army is conducting weed control actions in Bonamia habitat and monitoring phenology quarterly.

The individual found on the U.S. Navy's Lualualei Naval Reservation has been fenced for protection from cattle. A program of alien plant removal within the enclosure is ongoing.

Most of the B. menziesii at Kanepuu Preserve on Lanai are found within fenced enclosures. A planned fuel reduction treatment and fire protection plan are expected to enhance conservation of the B. menziesii plants found at the preserve.

This species has been successfully propagated at Lyon Arboretum's micropropagation laboratories, at Waimea Arboretum, and at the National Tropical Botanical Garden. Approximately 25 individuals existed in cultivation in 1997, although reintroduction of cultivated individuals to the wild had not yet been attempted.

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/

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

Reference

U.S. Fish and Wildlife Service. 10 November 1994. "Endangered Status for 12 Plants from the Hawaiian Islands." Federal Register 59 (217): 56333-56351.