if you mean the the knobby brown thing in the pot on the left, im goin with a new tuber,if they r really cramped, and theres no room for fresh tubers they do that

the one on the right is similar to the one on the left, with bumps(root nodes?), but not as thick and it has a stem growing. the one on the left is really round. they are both quite above the other, smooth tubers. they are too high up to cover them up with soil. so what should i do? cut them off and then replant into a sep pot, slightly above ground? i couldn't find any similar images anywhere or info to confirm. suppose i can leave them be until spring?

I dont think you have to do anything, I really like it! You could pop them off and and im sure they would grow, 99% sure. To be honest I havent seen any that look exactly like that, but I cant imagine it being anything else. If you do remove it spring would be better. A bigger pot would likely fix it too, but i wouldnt, you said they are happy, from that small pic they look it, I would just keep doin what you are doing for now, once they get that established, and you repot them, they can really go crazy, and get big if you want bigger then bump them up a pot size, but no more, they dont like lots of room. You will eventually have to repot at some point tho.

i tried to get a better pic for the one on the right - there are 5 stems (2 just giant) growing out of this thick nubby 'stem'. i think it's pretty established. so when i want to pop it out, i'll cut off a piece of tuber that this stalk is attached too. but since the stems are so big i am afraid even with tuber but without more roots it'll suffer. i could wrap some deer lichen (sold as moss) - very spongy thing - and mist it slightly and see if roots start developing and THEN cut it off? i rooted xmas cactus in deer lichen very well without any rot and very quickly too.

here's a pic of it against 2 doors for scale: the largest frond is 42", the other 38" and it's basically 3 feet wide . i removed a tie for the pic, but normally there a tie to support the stems since the 2 large ones are very heavy. and all in 7" by 6"H pot :). if i remember it sends out shoots in spring, so i'll wait for the buds to form to start working on it?

so there's news :one of the thick nubbly things produced a shoot. i also found an old post with a link very informative about zz's from exoticrainforest . but i don't see any recent posts from him/her. according to that link 'the nubby part' is the real stem. and is usually underground or on the surface. i guess in my case there's no room, so it's going vertical. but it seems that zz's are not propagated by tubers (he calles them rhizomes, he says they're not tubers) or tuber divisions. only by leaflets and seeds. so now i am confused: should i just cut off the nubbly stem right at the 'tuber' or should i cut a piece of tuber with it? or may be see, if i can separate whatever 'stems' are attached to one tuber and pop them off together? i don't want to do it now, when it's leafing out: it got like 4 strong shoots going. i want to wait until they fully grow.
here's the old post:see last one for a link. am not sure how to post the link to old thread.
http://forums.gardenweb.com/forums/load/aroid/msg050006561235.html

A rhizome is basically an underground stem of a plant. Once there's some growth on it you can probably cut it off and plant it on it's own and given proper growing conditions, it should be fine.

Steve Lucas, who wrote the exoticrainforest.com website, passed away about two years ago. That's why there has been no updates to the site or posts here by him.

i am sorry to hear that - loved reading his posts, very informative.
so it's not necessary to divide so that a tuber (those round potatoye things in the soil) is attached to the cut rhizome with growing leaves? obviously since my growing rhizome is above the soil level, it won't have any roots. will that be a problem? sorry for repeating - just can't find similar case discussed anywhere else.

If it was mine I would pack damp sphagnum moss around it and wait until it grew roots of it's own. When it does you can cut it off and plant it. You could just chop it off but they can be very slow growing at times, it may work out better if it still has a nutrient supply coming from the rest of the plant.

that's a great idea! i'll do that and maybe wrap a little plastic around loosely -sort of like for air-layering. and watch for roots. i moved both plants closer to the window while they are leafing out - hoping for denser leaves too. they'll be warmer now too in the western window with diffused light.

so about a month ago I repotted my 2 zz's. washed the tubers and roots: and separated into 4 pots. the roots were like orchid roots very healthy, but I cut off bottom half since they weren't fitting in the pots.
used new jungle mix soil recommended by exotic rainforest, free draining, mostly orchid bark, perlite and a little AV mix. I just moistened the perlite before mixing , so it was barely damp. and I did not water for 2 weeks, but the yellowing started and won't stop. after 3 weeks I pulled out the stalks to see that most roots have rotted and some tubers rotted too.
I trimmed tubers and most roots and put them in fresh orchid bark mix with about 40% perlite added. with may be a few tb of water with perlite. will wait 2 weeks to even dribble any water.
i am misting the leaves daily. after 1 week checked around tubers: pulled a few small rotting ones again, retrimmed, potted back.
it's been a total disaster - I have never seen such a collapse before. and I am pretty good with repotting and plants. it's a mystery. could it be I should not have bare rooted? no washing off of tubers?
will the clusters with 2-3 stalks survive without tubers and 2-3 inches of roots? i dusted everything with cinnamon heavily prior to potting.
I noticed some new root growth here n there, may 1/2".
they were such care free and healthy plants, i just can't believe what happened.
any ideas to help them survive?
they are near the western window with 2-3 hours of sunlight thru the sheers: which is where they've been growing like crazy with 4-6 new stalks before the repot.

Well this is a bummer! Wish I had some experience with this plant to babble about. Sending good vibes!

No water!
If its progressing or the soil won't dry, yank em out of the pot and get them dry!

I typed that and hit submit as soon as I could!
Ill be a bit more detailed

ZZ are true succulents, semitropical succulents maybe, but they are not big fans of water, I root cutting is dry medium, watered rarely, the cutting often yellow up bad.
Water in the presence if open wounds is bad, if its under the ground then u can count on numerous pathogens in there too! Bad news for and open wound on a plant that's not rapidly growing!
I'm going to guess that it was the root prune that caused this, I've noticed damaged zz roots often(always?) die off when severely damaged, such as being whacked in half... They may lose all the old roots, wet or dry, but if kept moist, and the tuber is below soil, which it almost certainly is, then rot may progress into the tuber, as you've seen!
Best case... You lose lots of leaflets. And several full fronds, the plants will never be the same, but given time can fully recover!
The worst case is grim, ur clearly a good gardener, no need to discuss worst case!
I have this same issue with zz, they just want to be left alone! I can't do that very well...

Don't give up hope tho, get em dry, then clean em up good, as u have been, I'd let em sit a day, maybe 2 out of the soil... And then once satisfied I had stopped the rot, I would prop them up in dry medium, not so super dry as perlite straight outta the bag, that will desiccate them, but very dry mix, as if they r planted, but they really won't be! And at that point I'd let them sit for a good long while, no direct sun, no pouring water, occasionally mist, and occasionally lift them from the medium and check for more rot, then reprop them up in the pot of dry mix.
This will keep their shape uptight and not twisted, and eventually u will start to see root progress, at the point I see even, ample root nubs distributed all around I'd then repot them in a more stable soil, basically, without roots the plants are cutting and need the same treatment...

I'm so sorry, they were marvelous plants! It's awful killing off plants u love, but u can save them, and restore them to their former glory!

thanks, grab! this gives me hope. now i am going to bore you to death with detail :).
do you think washing tubers and roots was bad idea?
i reviewed everything that you said. i dried only for 2 hours on initial repot. and the medium was only barely damp: guess even that was too much. should've dried for a day at least!
the 2nd repot was like you described (dry-pot). that was 1 week ago.
i had 2 completely 'naked' stems' after 2nd check-n-clean, and 1 with an inch of cut fat rhizome. so i stuck them in water with some rooting powder added and peroxide. i read that some people rooted the rachis in water within 1-2 weeks. so i tried - and they both have beginnings of roots after 1 week : 1/4" and sev nubs on the rizhome, which is not rotting ...yet..:). so that's encouraging.
i want to let them grow to 1/2" and then dust again with rooting powder and wrap the base with very slightly dampened almost dry sphagnum fibers, wrapped with dry coir matting and the whole plant bagged.
which is what i am doing with 2 other clusters that have only a few very short roots(2-3"), no tubers.
after a week they are showing white root nubs and there's no rot.
checked one 'dry-pot' after a week- had to trim 1/4" of the tuber. so as an experiment i decided to stick this one cluster with decent 3"x1" tuber into 'sphag-pad-and-bag'.
the tuber worries me, it's cut now.
should i pull it out and dry it for 24 hours?
i mist inside the bags on leaves only daily.
shag is not tight, just loosely piled - lots of air in between. do you think that's risky? i just did it today.
oh, my plants were all planted in such a way that tubers were just clearing the surface, not buried. i looked all over at images and they all show buried tubers. so when i replanted i buried mine shallow. in dry-pot for now that should be ok. but what about the final potting, when they have roots? should i raise the tubers to the surface like they were?

I yanked the cut tuber out to dry for 24 hours, just in case.

Good idea, always better safe(dry) that sorry...

I'd not add root hormone to rooted plants, I've had bad luck with that!

I'd not root them in water either but u have nothing to lose, maybe it'll work good for you, I've never tryied, so what do I know on that one...

Careful with the mist too, they rarely get dew mist or rain in situ...
I'd do more like 2x a week if that, I don't think they use much of it anyway, that glossy leaf keeps water in like its plastic, I think it's actually wax, but it can't let much water in either...

Also, as long as the dry pots stay real dry, that rot will stop advancing, I usually do one round of cutting rot off, after that it will help make a tougher scab, so don't cut anymore off fir a few days or a week, if there's new mushy spots, I'd only wipe them out, maybe scrap it of with my thumbnail if it was bad, but it usually just stops and drys up.

Glad I could be of some help, hopefully they will be shining stars again in a year or 2, the grow too slow to have very high expectations this year.

did just like you said, scraped the soft spot off.
I noticed that tubers sort of 'self-heal': on some spots when you pop the soft spot off it's nice clean surface underneath. and some tubers have many pock-marks like that. wonder if that's how they cope with rot?
what about keeping tubers on the surface, like they were planted before? should I do the same?
all pics that I see have them buried. but I think keeping them on the surface is probably safer.

I usually pull the tuber to the surface, in time they can pull themselves down, or fill in on the lower portion of the tuber, I'm not sure... Other times the soil will wash away from underneath and give the plant a stilted look, I don't think they like that alot but it doesn't stop them...

I would try to keep the tuber atleast somewhat exposed... For now anyway, if u want to fill it in later leave room in the pot for that, I think the tuber is the main attraction point!