|Listed||October 8, 1992|
|Description||Small perennial plant with smooth, long stems and greenish-white fleshy trumpet-shaped petals.|
|Habitat||Dark, narrow, rocky gulch walls in mesic to wet forests.|
|Threats||Habitat disturbance; predation by wild, feral, or domestic animals; low numbers.|
Pilo, Hedyotis mannii, is a perennial plant in the coffee family (Rubiaceae) with smooth stems that are usually 1-2 ft (0.3-0.6 m) long. The stem is woody at the base and four-angled. The leaves are opposite, thin in texture, elliptic to sometimes lanceolate, and are usually 3-7 in (7.5-18 cm) long. Stipules are attached to the slightly winged leaf stalks where they join and clasp the stem. The stipules are triangular and have a point 0.2-0.4 in (0.5-1 cm) long. The flowers of pilo are arranged in loose clusters up to 1 ft (0.3 m) long at the ends of the stems and are either bisexual or female. The green hypanthium is top-shaped with sepals at the top. The greenish-white, fleshy petals are fused into a trumpet-shaped tube; the capsules are top-shaped. Separating it from other species of the genus are its growth habit; quadrangular or winged stems; the shape, size, and texture of its leaves; and its dry capsule, which opens when mature.
This species typically grows on dark, narrow, and rocky gulch walls in mesic to wet forests at elevations of 490-3,450 ft (150-1,050 m). Associated plant species include mamaki, hapu'u, Cyanea (haha), and kopiko.
H. mannii was once widely scattered throughout Lanai, West Maui, and Molokai, in the Hawaiian Islands. After not being seen for 50 years, this species was rediscovered in 1987 by Steve Perlman on private land in Kawela Gulch on East Molokai. Only five plants were known to exist in this area in 1995. An additional nine plants of this species were discovered in 1991 on the island of Lanai—five mature and three juvenile plants at an elevation of 3,150 ft (960 m) at the head of Hauola Gulch and a single mature plant at 2,640 ft (800 m) in elevation in the gulch between Waialala and Kunoa Gulches. The Lanai populations in 1995 numbered 35-40 individuals, of which 20 occurred at Waialala and 15-20 at upper Hauola Gulch. Another population of 10-20 individuals was discovered in the early 1990s at Kauaula in West Maui. A total of 50-65 individuals of this species were thought to exist in the wild in 1995.
The limited number of individuals of H. mannii makes it extremely vulnerable to extinction by random naturally occurring events. Feral pigs and alien plants such as molasses grass degrade the habitat of this species and contribute to its vulnerability.
Conservation and Recovery
H. mannii seeds have been collected and propagated by the National Tropical Botanical Garden.
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
U. S. Fish and Wildlife Service
Pacific Remote Islands Ecological Services Field
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-1201
Fax: (808) 541-1216
U. S. Fish and Wildlife Service. 8 October 1992. "Determination of Endangered or Threatened Status for 16 Plants from the Island of Molokai, Hawaii." Federal Register 57 (196): 46325-46340.