A Reintroduction Success Story
Currently there are just two naturally occurring Cyanea truncata individuals remaining in the wild. The O‘ahu Plant Extinction Prevention Program (OPEP) has been working with this species since 2003 to insure its survival. Despite the extreme difficulty of reintroduced plants surviving successfully in the wild, Cyanea truncata is one of the few species for which reintroductions have been maturing and even fruiting. This is a direct result of intensive management by the OPEP program.
Cyanea truncata (Hawaiian name: hāhā) is a member of the Bellflower family (Campanulaceae) and is a palm-like shrub known from the wet, windward gulches of the Northern Ko`olau Mountains on O`ahu. This species has only ever been known from a handful of individuals scattered from Waiāhole to Kaipapa`u valleys where it is often found with native riparian/stream bank vegetation including Māmaki (Pipturus albidus), Ha`iwale (Cyrtandra sp.), Koki`o ke`oke`o (Hibiscus arnottianus), and many ferns and mosses.
The historically low numbers of individuals may be due to the environment this species inhabits - plants growing along stream banks may be washed away in large flood events. The low numbers of known plants may also be due to the lack of exploration in the wet gulches of the windward Ko`
C. truncata grows up to 2 meters (6.6 feet) tall and can be branched near the base. The leaves are stiff, up to 60 cm (23.6 inches) long, and are bunched near the top of the plant. This species can have up to 40 tubular flowers in a single inflorescence (stem). Individual flowers are 30-40 cm (11.8-15.7 inches) long and lavender to magenta and white striped. Ripe fruit are orange berries with brown shiny seeds embedded in the flesh.
This species, and other hāhā species, are assumed to have been pollinated by native Hawaiian honeycreeper birds (Lammers and Freeman, 1986). The tubular flowers of Cyanea species are decurved in the same shape and angle as presumed bird pollinators such as the `i’iwi (Vestiaria coccinea), a native honeycreeper bird. It is also assumed that the fruit of this species would have been eaten and spread by native birds, which are now extinct or much reduced in numbers. However, even with the decline of `i`iwi and other native nectivorous birds (Pratt, 1994) on O`ahu, C. truncata is still able to produce viable seeds.
OPEP is currently working with Kualoa Ranch to protect the remaining wild plants with ungulate fencing and weed control. Rat control occurs if insufficient fruit is able to be collected for propagation. There are no chemical slug control methods currently approved for forest use in Hawai`i and copper barriers are very labor intensive and have proven to be only minimally effective (Joe and Daehler, 2008). OPEP is also working to increase the population of Cyanea truncata through reintroducing plants that are large enough to withstand the pressure from slugs.
Today there are 16 reintroduced plants grown from the seed of three wild individuals that are within 3 ungulate-proof fences at both current and historic locations of this species.
References
Joe, S.M., and C.C. Daehler. 2008. Invasive slugs as under-appreciated obstacles to rare plant restoration: evidence from the
Lammers, T.G., and C.E. Freeman. 1986. Ornithophily among the Hawaiian Lobelioideae (Campanulaceae).: evidence from nectar sugar compositions. American Journal of Botany 73:1612-1619.
Pratt, H. D. 1994. Avifaunal change in the Hawaiian islands, 1893–1993. Pages 103–118 in A Century of Avifaunal Change in