Phyllostegia Glabra Var. Lanaiensis
Phyllostegia glabra var. lanaiensis
No Common Name
|Listed||September 20, 1991|
|Description||Tall perennial with red-veined leaves and white flowers, sometimes tinged with purple.|
|Habitat||Lowland wet forest.|
|Threats||Low numbers, alien plant species, axis deer.|
Phyllostegia glabra var. lanaiensis is a robust, erect to decumbent (reclining, with the end ascending), glabrous, and perennial herb in the mint family (Lamiaceae). Its leaves are thin, narrow, lance-shaped, 3.2-9.5 in (8-24 cm) long and 0.6-1 in (1.6-2.5 cm) wide, often red-tinged or with red veins, and toothed at the edges. The flowers are in clusters of six to ten per leaf axil, mostly at the ends of branches. The flowers are white, occasionally tinged with purple, and are variable in size, about 0.4-1 in (1-2.5 cm) long. The fruit consists of four small, fleshy nutlets. This variety is very similar to P. glabra var. glabra; it may be difficult to differentiate between the two taxa without flowers.
The habitat of P. glabra var. lanaiensis is lowland wet forest. It has been observed in the same habitat as Cyanea macrostegia ssp. gibsonii in mesic to wet forest in gulch bottoms and sides, often in quite steep areas.
P. glabra var. lanaiensis was known from only two collections made on the Hawaiian island of Lanai, one near Kaiholena; the two fertile specimens collected in 1914 remain the last obtained. A report of this plant from the early 1980s was most likely a misidentification of P. glabra var. glabra. The gulches and valleys of Lanaihale are rugged, steep, and only rarely explored, so there is hope that this species still exists. Finding it is made much more difficult by taxonomic confusion with the uncommon sympatric P. glabra var. glabra, especially since flowers are needed for a definitive determination.
It is possible that P. glabra var. lanaiensis no longer exists; if it still survives, the limited gene pool may depress reproductive vigor. Whether or not genetic limitations pose a problem, any natural or human-induced environmental disturbance could easily destroy any or all of the few remaining populations. Axis deer have not yet fully invaded the current habitat of this species, although they have directly, through browsing and trampling, and indirectly, through opening up avenues for invasion of alien plants by their foraging activities, contributed to the decline of this species. Browsing and habitat disturbance by axis deer promise to eliminate P. glabra var. lanaiensis if drastic management efforts are not undertaken. Even small pockets of virtually undisturbed forest in the heads of gulches on the upper slopes of Lanaihale are being invaded by strawberry guava, firetree, manuka, sourbush, molasses grass, Rubus rosifolius, and Paspalum conjugatum. These alien species have become pervasive on adjacent ridges because the forest floor is bombarded by alien propagules, and natural openings and openings created through habitat disturbance by axis deer provide ample sites for these aliens to take over and crowd out most native plants. Continuing disturbance by axis deer exacerbates the problem of alien plant invasion. The decline of native insect pollinators is very likely to pose a major, though undocumented, threat.
Conservation and Recovery
No conservation efforts were in progress as of 1999.
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
Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-1201
Fax: (808) 541-1216
Cuddihy, L. W., and C. P. Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities, and Introductions. University of Hawaii Cooperative National Park Resources Study Unit, Honolulu.
Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1990. Manual of the Flowering Plants of Hawai'i. University of Hawaii Press and Bishop Museum Press, Honolulu.