Viola lanaiensis

No Common Name

Description

Viola lanaiensis, a member of the violet family (Violaceae), is a small, erect, unbranched or little branched subshrub, 3.9-15.8 in (10-40 cm) tall. The leaves, clustered toward the upper part of the stem, are lance-shaped, about 2.3-4.3 in (6-11 cm) long and 0.5-0.98 in (1.2-2.5 cm) wide. Below each leaf is a pair of narrow, membranous stipules, about 0.4 in (1 cm) long. The flowers, 0.4-0.6 in (1-1.5 cm) long and white in color tinged with purple or with purple veins, occur from one to four per upper leaf axil. The fruit is a capsule about 0.4-0.5 in (1-1.2 cm) long. V. lanaiensis is the only member of the genus on Lanai.

When approximately 21 plants were observed in October 1992, one small fruit was noted; however, October may not have been the optimum time to observe flowering or fruiting. One sighting of this plant was on a relatively new landslide, and the rapid establishment of this species under these circumstances may reflect a high sensitivity to competition.

Habitat

The habitat of V. lanaiensis is lowland wet forest or lowland mesic shrubland. This species has been observed on moderate to steep slopes from lower gulches to ridgetops from 2,200-3,200 ft (670-975 m) elevation in mesic to wet areas, with a soil and decomposed rock substrate in open to shaded areas; it was once observed growing from crevices in drier soil on a mostly open rock area near a recent landslide. Associated vegetation includes ferns and short windswept shrubs or other diverse mesic community members such as Metrosideros polymorpha, Scaevola chamissoniana, Hedyotis terminalis, Hedyotis centranthoides, Styphelia, Carex, Ilex, Psychotris, Anti-desma, Coprosma, Freycinetia, Myrsine, Nestegis, Psychotria, and Xylosma.

Distribution

V. lanaiensis was first collected sometime between 1851 and 1855. It was known historically from scattered sites on the summit, ridges, and upper slopes of Lanaihale. Its habitat is wet or mesic forest or shrubland.

An occurrence of 20 V. lanaiensis individuals was known in the late 1970s along the summit road near the head of Waialala Gulch. That population has since disappeared due to habitat disturbance.

Three small populations are currently known, totaling fewer than 80 individuals. One population is located in Kunoa Gulch at an elevation of 2,660 ft (810 m); another is in the adjacent gulch to the northwest between Kunoa and Waialala Gulches at approximately 2,620 ft (800 m). The largest population, approximately 38 individuals, is in the extreme upper end of the northernmost drainage of Awehi Gulch just below Waiakeakua and south of Puhielelu Ridge. A total of 26 individuals were seen within a very restricted area in the vicinity of Awehi Gulch population during a site visit on October 20, 1992.

Threats

One of the primary threats to V. lanaiensis is the axis deer, which has largely invaded the habitat of this species. Axis deer have directly contributed to the decline of this species through browsing and trampling and indirectly through allowing alien plants to invade denuded places left by their foraging activities. Browsing and habitat disturbance by axis deer promise to eliminate V. lanaiensis if drastic management efforts are not undertaken.

The habitat of V. lanaiensis in gulches on the upper slopes of Lanaihale is being invaded by strawberry guava, firetree, manuka, sourbush, molasses grass, Rubus rosifolius, and Paspalum conjugatum. These alien species have become pervasive on adjacent ridges, then their propagules bombard the forest floor, obtaining a foothold in natural openings and the openings created through habitat disturbance by axis deer. Continuing disturbance by axis deer exacerbates this alien plant invasion problem.

With fewer than 80 scattered individuals in small populations, limited local gene pools may depress reproductive vigor in V. lanaiensis.

Since native birds may have been the pollinators of V. lanaiensis, their decline is very likely to pose a major, though undocumented, threat. Slug damage and live slugs have been observed on V. lanaiensis. The severity of this threat is unknown.

Conservation and Recovery

The Hawaii Plant Conservation Center in August of 1992 had a total of 55 V. lanaiensis seeds from Lanai in storage.

Contacts

U.S. Fish and Wildlife Service
Pacific Islands Ecoregion
300 Ala Moana Boulevard, Room 3-122
Box 50088, Honolulu, Hawaii, 96850
Telephone: (808) 541-3441
Fax: (808) 541-3470

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

References

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.

Culliney, J. L. 1988. Islands in a Far Sea: Nature and Man in Hawaii. Sierra Club Books, San Francisco.

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.