Lobelia gaudichaudii ssp. koolauensis

No Common Name

Description

Lobelia gaudichaudii ssp. koolauensis, a member of the bellflower family, is an unbranched, woody shrub 1-3.5 ft (0.3-1 m) in height. The inversely lance-shaped to rectangular leaves are 3-7.5 in (7.6-19 cm) long and 0.5-1.1 in (1.3-2.8 cm) wide. The leaf edges are thickened or curled under, fringed with hairs toward the base, and sharp-pointed at the tip. The flowering stalk is two to six-branched and 16-28 in (40.6-71.1 cm) long. The hairless bracts are lance-shaped to egg-shaped and 0.7-1.3 in (1.8-3.3 cm) long. The calyx lobes are triangular, lance-shaped, or egg-shaped, and 0.4-0.6 in (1-1.5 cm) long.

The greenish or yellowish-white corolla is 2-3 in (5-7.5 cm) long. The tubular portion of the flower is curved, with spreading lobes; the fruit is an egg-shaped capsule. The subspecies koolauensis is distinguished by the greenish or yellowish-white petals and the branched flowering stalks. The species is distinguished from others in the genus by the length of the stem, the length and color of the corolla, the leaf width, the length of the floral bracts, and the length of the calyx lobes. A specimen of L.gaudichaudii ssp. koolauensis was collected on Oahu in 1937, which was described the following year as a variety of L. gaudichaudii, naming it for the Koolau Mountains. The variety was elevated to a subspecies in 1988.

Habitat

L. gaudichaudii ssp. koolauensis typically grows on moderate to steep slopes in 'ohi'a or 'ohi'a-uluhe lowland wet shrublands at elevations between 2,100 and 2,400 ft (640 to 731.5 m). Associated plant taxa include alani, ko'oko'lau, naupaka, 'uki, and kanawao.

Distribution

L. gaudichaudii ssp. koolauensis was known historically from two populations in the central Koolau Mountains on Oahu; the number of extant populations has now been increased by two as a result of further field research. These four small populations occur on the Manana Ridge system in the central Koolau Mountains on privately owned land and on the Army's Schofield Barracks Training Area in the East Range. An additional population that is suspected to be L. gaudichaudii ssp. koolauensis occurs on the Kaipapau-Kawainui summit divide on land leased by the Army for Kawailoa Training Area; however, this cannot be confirmed until the individuals flower. The total number of plants was estimated to be fewer than 280 in 1997, thought to be about evenly distributed between the four populations.

Threats

The primary threats to the remaining populations of L. gaudichaudii ssp. koolauensis are habitat degradation and destruction by feral pigs, competition with the noxious alien plant Koster's curse, trampling by hikers, potential overcollection, landslides, and risk of extinction from naturally occurring events or through reduced reproductive vigor. L. gaudichaudii ssp. koolauensis is potentially threatened by feral pig predation because the plant is not known to be unpalatable to pigs and they favor plants from the bellflower family for food. It is possible that rats eat the fruit of L. gaudichaudii ssp. koolauensis, a plant with fleshy stems and fruit that grows in areas where rats occur. The noxious shrub Koster's curse is also a threat to the plant. Overcollection for scientific or horticultural purposes and excessive visits by individuals interested in seeing rare plants in natural settings could seriously damage L. gaudichaudii ssp. koolauensis, whose populations are close to trails and roads, thus giving easy access to potential collectors.

Erosion, landslides, and rockslides—events caused by natural weathering that often destroy individual plants and damage habitat—potentially threaten some populations of L. gaudichaudii ssp. koolauensis.

Conservation and Recovery

Seeds of L. gaudichaudii ssp. koolauensis have been collected by the National Botanical Garden. Enclosures should be constructed around populations of this species to reduce impacts from feral pigs. Subsequent control or removal of pigs from these areas will alleviate their impact on native ecosystems. Where fencing is not feasible due to topography or potential damage to sensitive habitat, snaring should be used as a means of ungulate control.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave. Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov

Reference

U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Oahu Plants." U.S. Fish and Wildlife Service, Portland, Oregon. 207 pp., plus appendices.