Cibotium | |
---|---|
Hāpuʻu ʻiʻi (Cibotium menziesii) | |
Scientific classification | |
Kingdom: | Plantae |
Division: | Pteridophyta |
Class: | Polypodiopsida/Pteridopsida (disputed) |
Order: | Cyatheales |
Family: |
Cibotiaceae sensu Smith et al. (2006) |
Genus: |
Cibotium Kaulf. (1820) |
Species | |
See text. |
See text.
Cibotium (from the Greek kibootion, meaning chest or box) is a genus of 11 species of tropical tree fern—subject to much confusion and revision—distributed fairly narrowly in Hawaiʻi (four species, plus a hybrid, collectively known as hāpuʻu), Southeast Asia (five species), and the cloud forests of Central America and Mexico (two species). Some of the species currently listed in the literature seem to be synonyms or local-variant subspecies. Cibotium glaucum, from Hawaiʻi, is the most frequently encountered Cibotium species in the horticultural trade, together with its sibling species Cibotium chamissoi and the potentially huge Cibotium menziesii. The remaining Hawaiian Cibotium, C. nealiae, is a 1-metre (3.3 ft) dwarf variety, restricted to the island of Kauaʻi that is never seen in the horticultural trade. Precise identification of Cibotium species is difficult, although all have shiny and rather waxy fronds when viewed from above, with varying degrees of powdery-pale blush when seen from underneath. The natural habitat of Cibotium is among the dripping trees and stream gulleys of the rainforests on Hawaiʻi's windward volcanic slopes.
Pressure on Hawaiian Cibotium habitats comes from development encroaching on the forested areas, especially the more accessible, lower-lying areas which are commercially attractive for land clearance. A less obvious threat comes from an invasive introduced tree fern species: Cyathea cooperi (the most popular garden tree fern in the United States), which has escaped from the islands' suburban gardens and now outcompetes the endemic flora. Wind-blown spores from this rapidly growing Australian import can migrate many miles into pristine Cibotium forests. This is a fairly recent phenomenon, but one which may eventually have grave consequences for the tree fern ecosystem in Hawaiʻi.