Cyathea is the largest (or one of the very largest) genus of ferns. I seem to recall that plant taxonomists remain in disagreement about whether all tree ferns are members of the same genus. At any rate, Cyathea (Sphaeropteris ?) cooperii might do well as a house plant if you can keep the humidity high and if you can accommodate its eventual size.

As for forcing Asplenium nidus to form a trunk: Is the birdsnest fern capable of forming a trunk? If so (and I doubt that it is), I'm wondering if I would want to do that. Its a beautful fern as is, and capable of growing to quite huge (trunkless) proportions even indoors.

I heard cyatheas need standing water and the trunks need to be watered, too.

As for the bird's nest ferns, these are some pictures I found:

http://lh6.ggpht.com/_5PQc7akQDCs/RhQlUrsbuCI/AAAAAAAAALQ/uweEtD3_ap0/100_2310.jpg

And http://foroantiguo.infojardin.com/showthread.php?t=172781 is in spanish, if anyone can read it. But it has this picture: http://www.infojardin.com/fotos/albums/userpics/tronco-asplenium-for-web.jpg

So, wondering if anyone can tell if that's actually a raised node/trunk/something similar, or just a weird potting arrangemenct.

We've got a couple Aspleniums at work that have trunks, though I'm not sure why them and not others: they all get more or less the same treatment. Could be something that just happens with age: some of our ferns have probably been in the greenhouse for a couple years or better.

My co-worker has advised me not to bring in any tree ferns, regardless of the genus, on the grounds that they've never done well for long in the greenhouse. Which, granted, the greenhouse does get pretty hot sometimes, and maybe that's all it is, but the way she says it gives me the feeling that keeping a tree fern indoors is possible in the same way that living in a permanent base on Mars is possible: no laws of physics would have to be broken in order for it to happen, but one would basically have to have complete control of all aspects of the environment at all times to make it work. It's only thirdhand experience, granted, and not very specific at that, but the way she said it got me over any interest in owning a tree fern I might ever have had.

Dicksonias are a less temperamental when it comes to humidity and constant moisture (but are are MUCH slower in growth). If you have a very cool room, they are not hard to overwinter (Cyatheas can be a pain though and go into sudden, inexplicable decline). Also, Blechnum brasiliense (red Brazilian tree fern) is surprisingly easy and beautiful! Just have to have my tree ferns!

Blechnums in general sound a lot easier. I'll have to keep an eye out for theme.

In regards to a. nidus, I get the impression that the rate at which the plant puts out new fronds has the most to do with it, which means it mostly would be a factor of age, although I'm wondering what sort of conditions would be favorable to it producing new fronds more quickly. I was guessing light. Some other post I read on gardenweb, which I can't find anymore, seems to imply that they like fairly constant, diluted fertilizer.