No Common Name
|Listed||October 29, 1991|
|Description||Shrub with terminal rosettes of narrowly elliptic leaves and clusters of magenta flowers.|
|Habitat||Exposed moist to dry cliffs.|
|Threats||Feral pigs and goats, alien plant species.|
Lobelia niihauensis is a low, branched shrub of the bellflower family in which each branch ends with a rosette of narrowly elliptic leaves, 3-6 in (7.6-15.2 cm) long. Clusters of magenta flowers appear at the ends of the branches. The fruits are egg-shaped capsules that contain numerous brown seeds. It flowers in late summer and early fall. Fruits mature one month to six weeks later. Plants are long-lived and are known to live as long as 20 years.
The species has been known by a variety of scientific names: L. niihauensis var. forbesii, L. niihauensis var. meridiana, L. tortuosa, L. tortuosa var. glabrata, L. tortuosa var. haupuensis, and L. tortuosa var. intermedia.
L. niihauensis grows on exposed moist to dry cliffs at elevations between 330 and 2,720 ft (100.5 and 829.1 m) in the Waianae Mountain Range on the western side of the island of Oahu and on the western portion of the island of Kauai. Associated plants include kawelu, kookoolau, Plectranthus parviflorus, Lipochaeta sp. (nehe), and ahinahina.
L. niihauensis, first described in 1931 from a specimen collected on the island of Niihau in 1912, also had historical occurrences on Oahu and western Kauai. The species was known on Oahu from Uluhulu Gulch to Nanakuli Valley in the Walanae mountains. On Kauai, it occurred from Limahnli Valley to near the Hanapepe River, as well as in the east at Nounou Mountain and the Haupu Range. L. niihauensis is now known to be extant only on these two islands. On Oahu, this species remains on Kamaileunu Ridge; Mt. Kaala; Kamaileunu; six locations in Waianae Kai; three locations in Makua Military Reservation, Nanakuli, and South Mohiakea Gulch; and six locations in Lualualei Naval Magazine. The 19 Oahu populations growing on federal, state, county, and city lands had a 1997 total of 718-753 individuals. This species is found on Kauai on state and private land in Waimea Canyon, on Poli-hale Ridge, along the Na Pali Coast, and in the Haupu Range. The 14 Kauai populations had a 1997 total of 960-2900 individuals. The 33 current populations on Oahu and Kauai combined totaled approximately 1,678-3,653 plants in 1997. The populations on Oahu are located within an area of about 85 by 10 mi (136.8 by 16.1 km); the western population on Kauai occurs in an are of 8 by 10 mi (12.8 by 16.1 km) and is about 23 mi (37 km) from the eastern Kauai population. While some populations are not well documented, at least 14 Oahu populations and four Kauai populations contain less than 13 individuals.
The main threats to L. niihauensis are habitat degradation and predation by feral goats, rats, and slugs; fire; military activities; and competition from the alien plant species Christmasberry, koa haole, daisy fleabane, Hamakua pamakani, and molasses grass.
Christmasberry, a tree introduced to Hawaii before 1911, forms dense thickets and may also release chemicals that inhibit the growth of other species. The koa haole tree is able to make its own nitrogen, enabling it to compete with native species adapted to low nitrogen soils. Molasses grass grows in dense mats that smother native vegetation.
In addition, some populations of L. niihauensis on Oahu are located near the U.S. Army's Makua Military Reservation and Schofield Barracks. Within a 14-month period from 1989 to 1990, 10 fires resulted from weapons practice on the reservation. In order to minimize damage from fires, the army has constructed firebreaks between the target areas and the surrounding forest.
Conservation and Recovery
The army has adopted a fire management plan that includes realigning targets and establishing firebreaks. Implementation of the plan may aid in protecting this species from fire. Completion of a boundary fence on the south and southeast perimeter of Makua Valley and continued goat control efforts, though limited, should help to protect the Makua-Keaau ridge plant from further goat damage.
This species is being propagated at the Lyon Arboretum and the National Tropical Botanic 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
Senior Resident Agent Office
U.S. Fish and Wildlife Service
300 Ala Moana Boulevard, Room 7-235
P.O. Box 50223
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-2681
Fax: (808) 541-3062
Cuddihy, L. W. and C. P. Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities and Introductions. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.
"Lobelia niihauensis." Beacham's Guide to the Endangered Species of North America. . Encyclopedia.com. (November 14, 2018). https://www.encyclopedia.com/environment/science-magazines/lobelia-niihauensis
"Lobelia niihauensis." Beacham's Guide to the Endangered Species of North America. . Retrieved November 14, 2018 from Encyclopedia.com: https://www.encyclopedia.com/environment/science-magazines/lobelia-niihauensis