No Common Name
|Listed||March 4, 1994|
|Description||Tufted shrub covered with tiny glands and straight hairs; lance-shaped leaves; and five to 11 maroon flower heads.|
|Habitat||Open a'ali'i-dominated lowlands or montane dry forests.|
|Threats||Competition from alien plants; browsing and habitat destruction by cattle, goats, and pigs; military exercises; fire; volcanic activity.|
Tetramolopium arenarium, an erect, tufted shrub 2.6-4.3 ft (0.8-1.3 m) tall, is covered with tiny glands and straight hairs. The alternate, toothless or shallowly toothed leaves are more or less lance-shaped, 0.6-1.5 in (1.5-3.8 cm) long. Five to 11 heads (dense flower clusters) are grouped at the end of each stem. Each head comprises a bell-shaped structure of 20-34 bracts 0.1-0.2 in (0.2-0.5 cm) high and 0.2 to 0.4 in (0.5-1 cm) in diameter beneath the flowers; a single series of 22-45 white, male ray florets 0.05-0.09 in (0.1-0.2 cm) long; and four to nine bisexual disk florets with maroon petals 0.12-0.17 in (0.3-0.4 cm) long. Fruits are compressed achenes 0.06-0.1 in (0.15-0.25 cm) long and 0.02-0.03 in (0.05-0.08 cm) wide. This species is distinguished from others of the genus by its erect habit; the presence and types of glands and hairs on the plant; the fewer heads per flower cluster; the larger, male ray florets; the fewer, bisexual, maroon-petaled disk florets; and the wider achenes.
This species typically grows in open a'ali'i-dominated lowlands or montane dry forests at elevations between 2,600 and 4,900 ft (792.5 and 1,493.5 m). Associated species include 'a'ali'a, pukiawe, 'akoko, and na'ena'a.
Since 1975, three populations have been identified and as of 1995 fewer than 400 individuals are known to exist. In 1989 about 39 reproductive individuals and 79 juveniles were found distributed over an area of 200 by 660 ft (61 by 201.2 m). This population was virtually extirpated by a fire that swept through Kipuka Kalawamauna in 1994. Only two individuals survived the fire and no seedlings appear to have reestablished. However, in 1994 two populations were discovered in the unburned portion of Kipuka Kalawamauna comprising about 32 and 350 individuals respectively.
Feral goats, sheep, and pigs have caused habitat destruction by browsing, trampling, and rooting. All known populations are transected by feral animal trails. Habitat decimation has resulted in opportunities for invasions by alien plant taxa, particularly Pennisetum setaceum (fountain grass). The occurrence of fountain grass increases the probability and intensity of fire. The small number of extant individuals and the restricted distribution of this taxon make it extremely vulnerable to random events and/or reduction of reproductive vigor. Un-warranted visits by unauthorized persons may compromise the integrity of these populations.
Conservation and Recovery
Seeds were germinated by staff at Colorado State University, and the viability and germination rates were high (90-100%) as was survivability of seedlings. Approximately 100 individuals were grown in a Colorado State University greenhouse in 1991. Out-planting in Kipuka Kalawamauna was attempted in 1991 with some success. Unfortunately, the few surviving plants were annihilated by the 1994 fire that swept through the kipuka. Dr. Timothy Lowrey at the University of New Mexico is conducting extensive research on the genetics of the genus and is establishing relationships among the taxa. The National Tropical Botanical Garden has germinated seeds and propagated the taxon.
Propagation and maintenance of ex situ genetic stock should continue. Habitat of existing populations should be protected from feral ungulates and managed for alien plant control. Steps should also be taken to ensure that plants will be protected from fire due to military exercises. Outplanting of propagated plants will likely be necessary to establish two more populations. T. arenarium occurs in Kipuka Kalawamauna, and to protect this area from fires, the U.S. Army has installed firebreaks and now redirects ordnance firing away from that kipuka.
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
300 Ala Moana Boulevard, Room 6307
P.O. Box 50167
Honolulu, Hawaii 96850
Telephone: (808) 541-2749
U.S. Fish and Wildlife Service. 4 March 1994. "Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for 21 Plants from the Island of Hawaii, State of Hawaii." Federal Register 59 (43): 10305-10325.