No Common Name
|Listed||September 20, 1991|
|Description||Unbranched shrub with narrowly elliptic leaves and a cluster of curved yellowish flowers.|
|Threats||Low numbers, alien plant species.|
Cyanea undulata, an unbranched or occasionally fork-stemmed shrub or subshrub of the bellflower family, is 1.5-15 ft (0.5-4.5 m) in height with narrowly elliptic leaves 11-17 in (28-43 cm) long and 1-2 in (2.5-5 cm) wide that have wavy margins, smooth upper surfaces, and fine rust-colored hairs covering the lower surfaces. The petiole (leaf stem) may be winged. The inflorescence is unbranched, 3-17 in (7.5-43 cm) long, and bears two to six flowers that are slightly curved, hairy, yellowish or greenish yellow and purplish at their base. Flowering material was collected from April to July. The fruit is an orange berry about 0.7 in (1.7 cm) long. The Hawaiian lobelioid species, including the genus Cyanea, are generally believed to have adapted to pollination by native nectarivorous passerine birds, such as the Hawaiian "honey-creepers". The long, tubular, slightly curved flowers of C. undulata fit this model, but field observations are lacking. The fleshy orange fruits of this species are adapted for bird dispersal like other species of Cyanea.
C. undulata is invariably found in the most pristine, undisturbed, and un-invaded sites, often on shady stream banks or steep to vertical slopes that are prone to erosion or landslides. Flowering occurs during the summer months, although adults do not seem to flower every year. C. undulata appears to grow slowly; consequently, it is likely to be damaged by any feral animal disturbance or alien plant invasion of its habitat. Microhabitat conditions for seed germination and growth also may be extremely specific.
C. undulata was described from two original collections made in the early 1900s. The type specimen was gathered in 1909 by Forbes in damp woods surrounding the Wahiawa swamp, and a now-lost collection was made in the same area by Lydgate in 1908. This species was collected in 1988 from a single population of three to four plants growing at about 2,300 ft (701 m) elevation along the bank of a tributary of the Wahiawa Stream.
Five adult and 23 juvenile plants are known from seven localities in the Wahiawa Drainage. Adults of C. undulata generally occur as scattered individuals, although several juveniles occasionally are found growing together. The high juvenile to adult ratio indicates that this species is reproducing, but the low total number suggests that regeneration is extremely slow.
The main threats to C. undulata are the species' extreme low numbers and competition from introduced alien plant species. With only three or four plants constituting the entire species population, C. undulata is highly vulnerable to extinction. An unpredictable human or natural event could easily destroy these plants. Although the Wahiawa drainage has been largely undisturbed, alien plant species are now spreading upstream. Strawberry guava (Psidium cattleianum ) and melastoma (Melastoma candidum ) are aggressive species that out-compete native species. They gained a foothold in the basin in 1982 when Typhoon Iwa opened sections of the forest canopy. This invasion is assisted by the actions of feral pigs which transport seed and open additional ground through their rooting. Although there are only slight indications of pig activity in the basin, any increase could quickly help spread invading plants.
Conservation and Recovery
No natural site or cultivated site conservation efforts have been attempted for C. undulata; however, certain other species of Hawaiian Cyanea have been successfully germinated and grown to seedling stage. The Fish and Wildlife Service published a Recovery Plan for the C. undulata in 1994.Only 28 individuals of this critically endangered plant are known to exist in the wild, all in the Wahlawa drainage. The critical habitat of the C. undulata must be protected from disturbances. The habitat must also be managed to reduce the damage caused by introduced mammalian herbivores, invasive alien plants, and other threats. The known individuals of the C. undulata must be monitored, and research undertaken into the biology of the species, habitat needs, and management practices to maintain and enhance its populations. The rare plant should be propagated in captivity, to provide stock for out-planting to enhance the tiny wild population.
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
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.
Stone, C. P., and J. M. Scott, eds. 1985. Hawai ' i's Terrestrial Ecosystems: Preservation and Management. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.
Lammers, T. G. 1990. "Campanlaceae." In Manual of the Flowering Plants of Hawai ' i, by W. L. Wagner, D. R. Herbst, and S. H. Sohmer. University of Hawaii Press and Bishop Museum 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.