Phyllostegia Kaalaensis

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Phyllostegia kaalaensis

No Common Name

ListedOctober 10, 1996
FamilyLamiaceae (Mint)
DescriptionMint with egg-shaped leaves and six flowers arranged along a flowering stalk and spreading, pointed teeth on the leaf edges.
HabitatMesic mixed (native/alien) forest or papala kepau-Sapindus oahuensis forest.
ThreatsHabitat degradation and destruction by feral pigs; potential fire; competition with the alien plants; and risk of extinction.


Phyllostegia kaalaensis, an herb of the mint family (Lamiaceae), has egg-shaped leaves that are 2-5 in (5-12.7 cm) long; usually six flowers are arranged along a flowering stalk. The calyx is glabrous and 0.2 in (0.5 cm) long. The hairless corolla tube is 0.4 in (1 cm) long, and the lower lip is 0.3 in (0.75 cm) long. The species is distinguished from others of the genus by the spreading, pointed teeth on the leaf edges and by the hairs along the margins of the calyx and bracts. Harold St. John described P. kaalaensis in 1987 from a specimen collected ten years earlier on Oahu by John Obata, Gerald Carr, and Daniel Palmer, naming it after its place of discovery. Warren Wagner of the Smithsonian Institution concurs that P. kaalaensis is a valid, taxonomically distinct species.


P. kaalaensis is found in mesic mixed forest or papala kepau-Sapindus oahuensis forest at elevations of 1,610-2,500 ft (490.7-762 m). Associated plant include huehue haole, 'ie'ie, opuhe, Claoxylon sandwicense (po'ola), and Hibiscus sp. (koki'o).


P. kaalaensis was known historically from only six scattered populations in the Waianae Mountains of Oahu.

Fewer than 40 plants were known from the six extant populations in 1997: 30 individuals occurred at Waianae Kai, six at Pahole Gulch, one each in two populations at Ekahanui Gulch, and one at Palikea Gulch. These populations occur on state land, including Pahole and Mt. Kaala Natural Area Reserves, and private land, including the Nature Conservancy of Hawaii's Honouliuli Preserve.


The major threats to P. kaalaensis are habitat degradation and destruction by feral pigs, potential fires, competition with alien plants, and risk of extinction from random natural events or through reduced reproductive vigor due to the small number of populations and individuals. The noxious weed Koster's curse and the smothering vine huehue haole threaten P. kaalaensis. Dense stands of strawberry guava threaten this species, as do the suffocating thickets of Christmasberry. Fire is also a potential threat to P. kaalaensis, which occurs in dry or mesic habitats where seasonal conditions exist for the easy spread of fire.

Conservation and Recovery

The U. S. 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 Botanical Garden, the Waimea Arboretum, and at the Division of Forestry and Wildlife's mid-elevation Nike facility at Pahole.


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


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