Dear all,
sorry that it took me ages once again to reply. I'm finding it very hard at the moment to find some time for the forum (and my tanks), what with work and all else.

Quote Originally Posted by timebomb
You're sure they are rhizoids, Francesco? It could be they are sex organs, you know. Take a look at these 2 pictures. The first one shows rhizoids while the second one shows the sex organs.
Thanks Kwek Leong, mine are definitely rhizoids. They are identical to the ones in the first picture.

Quote Originally Posted by stephan
One function of rhizoids is nutrient uptake.
This comes as a bit of a surprise to me. I thought their only function was to anchor the moss to whatever surface they grow upon.

Just theories, true, but it would be interesting to see if and how the mosses in Francesco's tanks would respond to additional CO2?
I added CO2 in my tank days after my last post and indeed it has responded wildly. It has now invaded the tank, leaving so little swimming space to the fish that soon I'll have to trim off most of it. However, only the Christmas Moss has continued growth in its 'regular' form. The Spiky and the 'Java' Moss are still growing elongated.

When I clear the tank of the excess moss, I'm going to tie the Spiky moss to the driftwood just like Kwek Leong did, and I'll also lower the pH (which should also benefit the Galaxy Rasboras and hopefully kick them into spawing mode). We'll see if the moss will revert to normal compact growth as it did in Kwek Leong's tank.

Thank you Stephan for all the interesting input you provided, and of course to KL for helping me identify the rhizoids and the insights into the KH/GH aspects.

Francesco