Xylosma crenatum

No Common Name

Description

Xylosma crenatum is a tree in the flacourtia family with dark grey bark that grows to a height of 40 ft (12 m). The oval to elliptical-oval leaves, 4-8 in (10-20 cm) long and 2.5-4 in (6.2-10 cm) wide, are somewhat leathery, roundly toothed, and moderately hairy underneath. The species is dioeceous, with individual trees producing either male or female flowers. The male flowers have not been described. Female flowers occur in clusters of three to 11 per leaf axils. They consist of four short oval sepals; petals are absent. More coarsely toothed leaf edges and hairy undersides of the leaves distinguish X. crenatum from the other Hawaiian members of this genus. The species has also been known by the name Antidesma crenatum.

Habitat

Xylosma crenatum is one of a large number of species endemic to the Kokee area in the northwestern part of Kauai. This area is roughly encompassed by the 8 sq mi (20.8 sq km) Kokee State Park. Xylosma crenatum is found in moist mountain forest dominated by ohia (Metrosideros polymorpha ) and koa (Acacia koa ) at elevations between 3,200 to 3,500 ft (960 to 10,500 m).

Five other plant species endemic to the Kokee region are federally listed as endangered: Chamaesyce halemanui, Dubautia latifola, Hawaiian bluegrass (Poa sandvicensis ), Poa siphonoglossa, and Stenogyne campanulata.

Distribution

Xylosma crenatum was originally known on Kauai only from along upper Nualolo Trail in Kuia National Area Reserve and along Mohihi Road between Waiakoali and Mohihi drainages in Na Pali-Kona Forest Reserve. There were just six individuals along Nualolo Trail in 1994. New populations were discovered in 1994 at Honopu Valley in Kokee State Park, Nawaimaka Valley in Na Pali-Kona Forest Reserve, and Mahanaloa Valley; one, five, and one were the respective number of individuals at each location.

Threats

Hurricane Iwa caused extensive damage in 1982 to vegetation in the Kokee region of Kauai. It is believed that the two trees at the Nualolo Trail site were destroyed by the storm. Since only one male Xylosma crenatum is now known to exist, regeneration of the species cannot occur unless at least one female tree is discovered.

A single human or natural event could render the species extinct; evidence of such a near disaster was found in 1989, when freshly bulldozed earth from road maintenance was found next to the tree.

Conservation and Recovery

Xylosma crenatum has been successfully propagated and then cultivated by National Tropical Botanical Garden, and this currently has seeds in storage and plants growing in its garden. The Lyon Arboretum also holds seeds.

The Division of Forestry and Wildlife fenced the Kuia Natural Area Reserve population, and out-planted propagated individuals.

Contact

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

References

U.S. Fish and Wildlife Service. 13 May 1992. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Six Plants from the Kokee Region, Island of Kauai, Hawaii." Federal Register. 57 (93): 20580-20587.

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.