There's one particular species of Hawaiian tree fern, Cibotium nealiae, that is only found on Kauai - nowhere else. And it doesn't exist in the garden trade either. It's much smaller than your other three Cibotium species - the trunk never exceeds a metre high - but in all other respects shares the general family characteristics: waxy, shiny looking fronds when viewed from above, but with a powdery-pale blush when seen from underneath. They occur in Kauai's dripping forest slopes and stream gulleys right up to cloud level. Separating this one out from the other Hawaiian Cibotium tree ferns would be hard, but the diminutive trunk height would be the thing to look for. Lots of tiny trunked Cibotiums all together - in a Kauai forest, of course - would almost certainly be thie right one.
Are there any Kauai correspondents here (or visitors) that can tell me if they know this dwarf tree fern? I'd especially like to hear from anybody with regular access to the places that this one grows. I'm pretty desperate to get my hands on a photo and hopefully a small frond sample.
Steve - Brighton, Sussex Coast, UK