Holokea (Cyanea horrida)
|Also known as:||prickly cyanea|
|Size||Height: 1 – 4 m (2)|
Holokea is classified as Critically Endangered (CR) on the IUCN Red List (1).
As of 2003, less than 20 individuals of this incredibly rare plant were believed to remain (2). Holokea is a palm-like tree, with leaves composed of leaflets arranged each side of a central stalk. Each leaf measures 20 to 37 centimetres long, and 10 to 19 centimetres wide, and has a green upper surface that bears small, sharp projections. The underside is a paler shade of green, and is covered with hairs as well as small, sharp projections (2). The flowers of holokea are borne in clusters of five to eight, and whilst each flower is just one centimetre wide and eight centimetres long, their attractive colouring (blackish-purple or greenish-white tinged with purple), makes them clearly evident amongst the green leaves. At certain times of the year, holokea also bears yellow berries, each one measuring up to 2.5 centimetres long (2).
Holokea inhabits rainforest and the edges of subalpine forest, at altitudes between 1,520 and 2,000 metres (2).
The prickles borne on the leaves of holokea are believed to have evolved as a defence against flightless geese and geese-like ducks that used to inhabit the Hawaiian Islands, but which became extinct well over 1,000 years ago (3).
This Critically Endangered species is thought to be threatened by the impact of feral pigs, weeds, as well as possibly rats and invertebrates (1) (4). Holokea's tiny population also makes it incredibly vulnerable to natural events such as disease, extreme weather, and fire, which could have a catastrophic impact on the species.
There appear to be no specific conservation measures currently in place for this extremely rare species.
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Invertebrates: animals with no backbone.
IUCN Red List (January, 2008)
- Wagner, W.L., Herbst, D.R. and Sohmer, S.H. (1999) Manual of the Flowering Plants of Hawai’i. Bishop Museum Press, Honolulu.
- Givnish, T.J., Sytsma, K.J., Smith, J.F. and Hahn, W.J. (1994) Thorn-like prickles and heterophylly in Cyanea: adaptations to extinct avian browsers on Hawaii?. Proceedings of the National Academy of Sciences of the United States of America, 91(7): 2810 - 2814.
NatureServe (August, 2008)