|Listed||February 25, 1994|
|Description||Moderately or densely branched shrub with knobby branches, green flowers that have five or six petals, and pale yellow fruit.|
|Habitat||Montane wet forests.|
|Threats||Goats, pigs, rats, alien plants, fire, natural disaster, limited numbers.|
Heau (Exocarpos luteolus ) is a moderately or densely branched shrub in the sandalwood family that grows to a height of 1.6-6.6 ft (0.5-2 m). The branches are knobby and the leaves are of two kinds: minute scales and more typical leaves. The latter, which are usually present, are elliptical, lace shaped or oval, about 2-3.2 in (5.1-8.1 cm) long and 1-1.4 in (2.5-3.6 cm) wide, and lack a leaf stalk. The green flowers have five or six petals about 0.04 in (1 mm) long. The pale yellow fruit, usually 0.4-0.7 in (1-1.8 cm) long, is a drupe with four distinct indentations at the apex. About 0.2-0.4 in (5.1-10.2 mm) of the drupe is exposed above the fleshy, golden-yellow receptacle. This species is distinguished from others of the genus by its generally larger fruit and four indentations, and by the color of the receptacle and fruit.
E. luteolus is found at elevations of 2,000-3,600 ft (610-1,097 m) in wet places bordering swamps; on open, dry ridges; and in lowland to montane 'ohi'a-dominated wet forest communities. Associated vegetation includes koa, pukiawe, and uluhe.
E. luteolus was known from historical occurrences on Kauai at Wahiawa Swamp, Naholuamanu, and Kumuwela Ridge.
The species is now known to occur in 12 populations of about 324-349 total individuals scattered on state land. These locations include Kumuwela Ridge, Kauaikinana Valley, near Honopu Trail, Waialai, and on the rim of Kalalau Valley at the boundary of Kokee State Park in an area of 3 sq mi (7.8 sq km) and about 16 mi (25.7 km) away on Kamali Ridge in Kealia Forest Reserve. Other extant populations occur in the Na Pali Kona Forest Reserve at Nawaimaka, Pohakuao, Koaie Canyon, and Awaawapuhi; in the Alakai Swamp; and along the Wahiawa Mountains.
Destruction of habitat by feral goats and pigs and competition with daisy fleabane are the major threats to this species. Aggressive alien plants degrading this plant's habitat include black wattle, karakanut, firetree, and prickly Florida black-berry—all woody plants that displace native Hawaiian species. Other threats include rats that eat the fruits, goats that browse the plants, fire, erosion, and overcollecting for scientific purposes.
Conservation and Recovery
E. luteolus has been successfully propagated by National Tropical Botanical Garden, where seeds are also currently in storage. The Lyon Arboretum had six seeds in tissue culture in 1995.
The Division of Forestry and Wildlife fenced a plant sanctuary in the Kalalau Rim area.
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
Pacific Remote Islands Ecological Services Field
300 Ala Moana Blvd., Room 3-122
P. O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-1201
Fax: (808) 541-1216
U. S. Fish and Wildlife Service. 25 February 1994. "Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for 24 Plants from the Island of Kauai, HI." Federal Register 59 (38): 9304-9329.