Tetramolopium Rockii

views updated

Tetramolopium rockii

No Common Name

ListedOctober 8, 1992
FamilyCompositae (Asteraceae)
DescriptionShrub with short spatula-shaped leaves with long silky hairs on surface.
HabitatHardened calcareous sand dunes or ash-covered basalt in the coastal spray zone or coastal dry shrublands and grasslands.
ThreatsHabitat disturbance, and predation by wild, feral, or domestic animals.


Tetramolopium rockii is a glandular, ciliated, and prostrate shrub of the aster family that forms complexly branching mats 2-4 in (5.1-10.2 cm) tall and 3-16 in (7.6-40.6 cm) in diameter. T. rockii var. calcisabulorum, a variety of T. rockii, has leaves with slightly rolled edges that are 0.8-1.2 in (2-3 cm) long; these leaves are given a whitish appearance by their long silky hairs. T. rockii var. rockii, the nominative variety, has smaller, flat, and less hairy leaves that are yellowish-green. The leaves of both varieties are spatula-shaped with glands and smooth margins. The flower heads are arranged singly at the ends of the flowering stalks that have a hemispherical involucre. There are approximately 50-100 white ray florets, surrounding 30-55 functionally male, yellow, and funnel-shaped disk florets. The fruit is achene and is topped with white bristles. This species distinguishes itself from other Tetramolopium species by its growth habit, ciliated glandular surface, spatulate leaf shape, and yellow disk florets.


T. rockii is restricted to hardened calcareous sand dunes or ash-covered basalt in the coastal spray zone or coastal dry shrublands and grasslands between 30 and 650 ft (9.1 and 198.1 m) on West Molokai. Associated plants species include Frimbristylis cymosa, hinahina, nehe, 'ilima, and 'aki'aki.


Of the two recognized varieties of T. rockii var. rockii was first discovered at Moomomi during the early twentieth century and is still extant in that area. T. rockii var. rockii remains on West Molokai from Kapalauoa to Kahinaakalani and on East Molokai at a location north of Kalawao on Kalau-papa Peninsula. Variety calcisabulorum is only reported west of Moomomi, from west of Manalo Gulch to Kalani, intergrading with variety rockii where their ranges overlap. The only known population of T. rockii var. calcisabulorum and the scattered populations of T. rockii var. rockii extend over a distance of about 4.5 mi (7.2 km) along the northern coast, sometimes locally dominating the vegetation. Twelve miles (19.3 km) to the east, the Kalawao population of var. rockii encompasses approximately 95 acres (38.4 hectares). The four populations had an estimated 1992 total of 174,000 individuals.


Stochastic events or extreme climatic changes could adversely affect this species because of its restricted distribution. Although T. rockii is threatened to some degree by competition with alien plants, habitat destruction and predation by feral animals, fire, and the pressures of various human activities, the relatively large number of existing T. rockii individuals reduces the likelihood that this species will become extinct in the near future.

Conservation and Recovery

Seeds of both varieties of T. rockii 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

Pacific Islands Ecological Services Field Office
Room 6307, 300 Ala Moana Blvd.
Honolulu, Hawaii 96850
Telephone: (808) 541-2749
Fax: (808) 541-2756


U.S. Fish and Wildlife Service. 8 October 1992. "Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for 16 Plants from the Island of Molokai, Hawaii." Federal Register 57 (196): 46325-46340.