Viola helenae

No Common Name

Description

Viola helenae is a small, unbranched subshrub in the violet family with an erect stem between 1 and 2.5 ft (0.3-0.8 m) tall. The hairless leaves clustered on the upper part of the stem are lance-shaped, 3-5 in (7-12 cm) long, and 0.8-l in (2-2.4 cm) wide. The pale lavender or white flowers are less than 0.4 in (1 cm) long and are produced on stems about 1.8 in (4.5 cm) long, either singly or in pairs in the leaf axils. Flowers and immature fruits were collected in April, and mature fruits were collected in October. The fruit is a capsule 0.5 in (1 cm) long that splits open at maturity, releasing the pale olive brown seeds 0.1 in (0.2 cm) long.

Little is known about the life history and ecology of V. helenae. The flowers are all chasmogamous (open at maturity for access by pollinators), none being cleistogamous (remain closed and self-fertilize in the bud) as in certain other violets. It is likely that its flowers require pollination by insects for seed set. Mature flowering plants do produce seed; however, seed viability may be low and microhabitat requirements for germination and growth may be very specific. Seeds planted at the Hawaiian Plant Conservation Center nursery failed to germinate, either because they may not have been sufficiently mature when collected or possibly just because violet seeds are often very slow to germinate. The seeds are jettisoned when the capsule splits open, as in most species of the genus.

This single-stemmed woody violet seems to grow and reproduce extremely slowly and is apparently very sensitive to disturbance. A previously known population on the bank of a tributary no longer exists; the plants presumably died out after the canopy was disturbed by Hurricane Iwa in 1983 and subsequently invaded by alien species.

Plant growth rates, longevity, pollinators, ecology, and the age at which individuals begin flowering are all unknown for this species.

Habitat

Three populations of this species occur on stream banks, valley bottoms, or slopes, usually in light to moderate shade. Two of these occurrences were in relatively undisturbed areas with no incursions by alien plants, while one was moderately invaded by alien species.

Two small populations of V. helenae were found growing on the windward side of a windswept, exposed ridgetop among stunted Dicranopteris, an unlikely habitat for this species. The plants are atypically small for V. helenae, and further study is required to determine if they are conspecific or represent another species.

Distribution

There were probably fewer than 30 V. helenae plants occurring near the Wahiawa Bog in 1971 in a small area at 2,000 ft (610 m) elevation along Wahiawa Stream. By the fall of 1991, this violet was known from two populations of about 13 total individuals along either branch of the Wahiawa Streams. Further observations in the fall of 1992 gave a revised count of five V. helenae populations of 137 total individuals, 89 adults and 48 juveniles, in the Wahiawa Drainage.

Threats

The most important present threat to the V. helenae is competition and habitat damage caused by invasive alien plants. It is also at risk from feeding by introduced mammalian herbivores, and possibly from a lack of native pollinators. It is also potentially threatened by the intrinsic risks of extinction associated with having a perilously tiny population (only about 137 plants are known to exist).

Conservation and Recovery

An attempt was made to propagate V. helenae through cultivation in 1971, when six small plants were collected and brought to the National Tropical Botanical Garden on Kauai. Two were placed on tree fern logs and the roots covered with sphagnum, and four were potted in soil. The plants were placed under mist for a few days, then transferred to a plastic case. Although one plant with buds actually flowered, all died within five months. In mid-1991, two lots of seeds (14 and 64 seeds, respectively) were collected by Hawaii Plant Conservation Center staff for propagation at National Tropical Botanical Garden, but no germination has resulted to date, possibly because the seeds were not mature enough. V. chamissoniana ssp. chamissoniana, another Hawaiian endemic, has been successfully grown from seeds in the Hawaii Plant Conservation Center nursery.

Contacts

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

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

References

Cuddihy, L. W., and C. P. Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities and Introductions. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.

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

St. John, H. 1979. "Resurrection of Viola helenae Becker." Hawaiian Plant Studies 90. Phytologia 44:323-324.

St. John, H. 1989. "Revision of the Hawaiian Species of Viola (Violaceae)." Bot. Jahrb. Syst. 111(2):165-204.

Stone, C. P., and J. M. Scott, eds. 1985. Hawaii's Terrestrial Ecosystems: Preservation and Management. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.

U. S. Fish and Wildlife Service. 1994. Recovery Plan for the Wahiawa Plant Cluster: Cyanea undulata, Dubautia pauciflorula, Herperomannia lydgatei, Labordia lydgatei and Viola helenae. U. S. Fish and Wildlife Service, Portland, Oregon.

Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1990.Manual of the Flowering Plants of Hawaii. University of Hawaii Press and Bishop Museum Press, Honolulu.