Cibotium is a family of perhaps a dozen tropical tree fern species - subject to much confusion and revision - distributed fairly narrowly in Hawaii, Southeast Asia and the cloud forests of Central America. Some of the species currently listed in the literature seem to be synonyms or local-variant sub-species. Cibotium glaucum, from Hawaii, is the most frequently encountered Cibotium species in the garden trade, together with its sister species C. chamissoi and the potentially huge C. menziesii. The remaining Hawaiian Cibotium species, C. nealiae, is a one-metre dwarf variety, restricted to one island, and never seen in the horticultural trade. Precise identification of the Hawaiian Cibotiums is difficult, even for experts, however all have shiny and rather waxy fronds when viewed from above, with varying degrees of powdery-pale blush when seen from underneath. The dripping forests and stream gulleys of Hawaii's volcanic slopes are the Cibotiums' natural habitat.

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. Another less obvious threat comes, somewhat ironically, from an invasive introduced tree fern species _ Cyathea cooperi, the most popular garden tree fern in the US - which has escaped from the islands' suburban gardens and now out-competes the endemic flora. Wind-blown spore 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 ecology in Hawaii.

The other Cibotiums that often surface in botanical collections are C. schiedei and C. regale (Mexico), plus C. barometz (Asia). The latter species is best known for its role in ancient medicine, and even today its hairs are a staple ingredient in ointments used in natural Chinese remedies. The medieval world was beguiled by stories that claimed Cibotium barometz - the 'Scythian Lamb' - was in fact half-sheep, half vegetable!

There are no publically accessible Cibotium collections growing outdoors in the United Kingdom _ although they are sometimes glimpsed in Californian garden designs _ but there are two outstanding glasshouse collections at the Royal Botanical Gardens, Kew, and at RBG Edinburgh in Scotland.