Kolea (Myrsine linearifolia)
|Listed||October 10, 1996|
|Description||Branched shrub with linear leaves that are yellowish-purple toward the base.|
|Habitat||Mesic to wet 'ohi'a forests.|
|Threats||Competition with alien plants; habitat degradation by hoofed mammals.|
Myrsine linearifolia, a variety of kolea, is a branched shrub of the myrsine family (Myrsinaceae) that reaches 8.2-26.2 ft (2.5-8 m) in height. The slightly fleshy, linear leaves are 1.7-3 in (4.3-7.6 cm) long, 0.09-0.14 in (0.2-0.3 cm) wide, often yellowish purple toward the base, and tend to be clustered toward the upper branches. The margins of the leaves are smooth and roll slightly toward the underside of the leaf. One to three apparently perfect (containing male and female parts) flowers, on stalks 0.04-0.17 in (0.1-0.4 cm) long, occur in clusters among the leaves. The greenish petals are inversely lance-shaped, about 0.09-0.1 in (0.2-0.25 cm) long, and also have margins fringed with hairs. At maturity, the fruits are black elliptic-shaped drupes about 0.2 in (0.5 cm) long. This species is distinguished from others of the genus by the shape, length, and width of the leaves; length of the petals; and number of flowers per cluster.
M. linearifolia typically grows in mesic to wet 'ohi'a forests that are sometimes co-dominant with 'olapa or uluhe from 1,920 to 4,200 ft (585 to 1,280 m) in elevation. Plants growing in association with this species include 'ahakea, 'aiea, alani, Eurya sandwicensis (anini), kopiko, Lysimachia sp., and native ferns.
M. linearifolia was known historically from nine scattered locations on Kauai: Olokele Valley, Kalualea, Kalalau Valley and Kahuamaa Flat, Limahuli-Hanakapiai Ridge, Koaie Stream, Pohakuao, Namolokama Summit Plateau, and Haupu.
The eight currently known populations, seven of which are historical locations, occur on state and private land at Kalalau Valley, Kahuamaa Flat, Limahuli Valley, Hanakapiai Ridge, Koaie Stream, Pohakuao, Namolokama Summit Plateau, and Wahiawa Drainage. The largest population, located in Kalalau Valley, contains several hundred individuals. The remaining seven populations total about 100 plants; hence, approximately 1,000-1,500 individuals are known for the entire species.
Competition with the alien plants daisy fleabane, lantana, prickly Florida blackberry, strawberry guava, thimbleberry, and air plant and habitat degradation by hoofed mammals such as pigs and goats are the chief threats to M. linearifolia. Although populations of this species are threatened by rat and goat predation, habitat modification by pigs and goats, and competition with alien plant species, the wider distribution of occurrences through a relatively large area and greater numbers of individual plants reduce the likelihood that M. linearifolia will become extinct in the near future.
The Wahiawa Mountains population of M. linearifolia is threatened by feral pigs. Pigs also constitute a potential threat to the Pohakuao and Kalalau cliffs populations. Habitat degradation reported to occur in areas near these populations, if not controlled, may become a problem for these occurrences. The Kalalau cliffs and Namolokama Summit plateau populations of this plant are threatened by goats. An invasion of daisy fleabane on the Kalalau cliffs threatens M. linearifolia ; air plant, an herb which occurs on all the main islands except Niihau and Kahoolawe, threatens the Pohakuao population; prickly Florida blackberry threatens the Koaie Stream and Pohakuao populations; and thimble-berry threatens the Limahuli Valley and Hanakapiai Ridge populations.
Conservation and Recovery
M. linearifolia has been successfully propagated from seeds and tissue culture, and two plants were in cultivation on the grounds of the National Tropical Botanical Garden; however, these plants have since died.
Maintenance of adequate cultivated genetic stock should be continued. Additional wild seeds should be collected periodically until the cryopreservation method of long-term storage is perfected. This will insure that viable seed stock is available for out-planting.
A long-range management plan to control alien plant species in the eight populations, with special emphasis on the largest population located in Kalalau Valley, which contains several hundred individuals, remains to be developed.
U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
U.S. Fish and Wildlife Service. 1988. "Kauai II: Addendum to the Recovery Plan for the Kauai Plant Cluster." U.S. Fish and Wildlife Service, Portland, Oregon. 84+ pp.