Lobelia monostachya

No Common Name

Description

Lobelia monostachya, a member of the bellflower family, is a prostrate woody shrub with stems 6-10 in (15.2-25.4 cm) long and leaves 2.8-6 in (7.1-15.2 cm) long and 0.2-0.3 in (0.5-0.75 cm) wide. The flowering stalk is unbranched. The pale magenta corolla is 0.6-0.7 in (1.5-1.8 cm) long and approximately 0.2 in (0.5 cm) wide; the lobes of the corolla overlap spirally. The species is distinguished from others in the genus by the narrow, linear leaves without stalks and the short pink flowers. A new variety of L. hillebrandii was described in 1919 from a specimen collected in the 1800s, naming it L. hillebrandii var. monostachya. This variety was elevated to the species level in 1974 and was transferred to a new genus as Neowimmeria monostachya. The species was transferred back to the original genus as L. monostachya in 1988.

Habitat

L. monostachya occurs on steep, sparsely vegetated cliffs in mesic shrubland at an elevation of about 950 ft (289.5 m). Associated plant taxa include ahinahina, Carex meyenii, moa, and kawelu.

Distribution

L. monostachya, known only from the Koolau Mountains and not seen since its original discovery in the 1800s in Niu Valley and in the 1920s in Manoa Valley, was rediscovered by Joel Lau in 1994 at a previously unknown location in Wailupe Valley on state-owned land. Eight additional plants have since been located in the same area where Lau found his one plant, bringing the 1997 total of known individuals to nine.

Threats

The major threats to L. monostachya are predation by rats; competition with the alien plants Christmas berry, Hamakua pamakani, Kalanchoe pinnata (air plant), and molasses grass; and risk of extinction from naturally occurring events or through reduced reproductive vigor due to the low number of individuals in the only known population. L. monostachya is potentially threatened by feral pig predation because the plant is not known to be unpalatable to pigs, who favor plants from the bellflower family for food. Rat damage has also been observed in the only known population of L. monostachya. Christmas berry grows in dense thickets that threaten L. monostachya. The mat-forming weed Hamakua pamakani is a threat to this species. Air plant, an herb that occurs mostly in dry to mesic areas on all the main islands except Niihau and Kahoolawe, poses a significant threat to the only population of L. monostachya.

Molasses grass also threatens this sole population through the smothering mats it forms and the intense fires it can fuel.

Conservation and Recovery

L. monostachya is being propagated at the Lyon Arboretum. The remaining population needs to be weeded and protected immediately. A management plan to control rats, a potential serious threat to this species, should be developed and implemented. This strategy should include the use of the currently approved Diphacinone bait blocks and then the broader-scale application of rodenticide though aerial dispersal.

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.