Also, zetsu appears to grow from the mazou. If true then it might mean zetsu contains some of madara's energies as well, as it us believed at this point he is contributing them along with what he gained from hashirama. Obito's would theoretically not need a zetsu body as he already naturally has the uchiha ingredients found in madara, to what degree remains to be seen. Back to zetsu, though i believe zetsu as an entity must be defined as person, regardless if cloned zero times, 100,000 times, black or white, zetsu is person. Obito's body contains no person other than obito (at the point of flashback, i know some think he absorbs zetsu). His half body clearly is hashirama matter devoid of zetsu.
I can settle peacefully with "not enough info" but then claims of obito's mokuton can't be confidently attributed to spiral zetsu or the like.
If obito's hashirama body allows him to absorb zetsu ( cellular compatibility, zetsu can move freely through "wood" etc.) Then what are the chances obito can absorb any number of zetsus? Each absorption gaining him their knowledge, memory, experience in the way of shadow clone dispersal. Not only that, his hashirama components would power up significantly as he receives the chakra of each zetsu!
Zetsu has shown limited mokuton, obito has shown incredible mokuton.
Zetsu imitates chakra signatures, obito has never been confirmed to have this ability. He is not half zetsu, he is half hashirama.
The mazou behind old madara, the white zetzus, and the prothesis on Obito are all the same material. But...
The zetzus were given something extra, that the mazou and the prosthesis don't have: a consciousness.
There are at least 2 white zetzus with a consciousness: the two talking to each other about poo.
The spirale zetsu might be dead. Not talking anymore to the actual Tobi.
The second zetsu might be the one who is alive nowdays = the one having merged with black zetsu = the one with the 100.000 clones.
The origine of the consciousness of the 2 white zetsu is still to be determined. The origine of black zetsu too.
As for the power to use mokuton:
The material is not enough. You need a mind/chakra/skill in addition to the material, in order to use/control it.
White zetsu and Danzo don't have it.
Harashimara, actual edo madara with implant, Obito with implant, Yamato do have it.
On a side note, Naruto seems to have the mind/chakra/skill for it (ref: trees growing next to him), but he miss the cells/implant.
So how Obito with implant is using the mokuton?
He's obviously using his own mind/chakra/skill in combination with the Harashimara cells. He has those cells both in the prosthesis and in the spiral zetsu around him. Theorethically I would say he could use either of the two. Yet considering that the actual Tobi is not using mokuton anymore, still has the prosthesis, and doesn't seems to have the spiral zetsu anymore to talk to, it would seem that Obito was using the cells from the spiral zetsu and not from the prosthesis to make the mokuton.
Is it just black wood or is it the well known chakra rods used by the rinnegan's user? Obito had no rinnegan at the moment he suddently could use the mokuton and the rods appeared.
On the other hand Nagato used the rinnegan to summon the mazou, and then the mazou forcely pierced Nagato's body with the rods. But here we already have a Mazou. So no need of Rinnegan, I guess.
Madara is attached to the mazou, nagato has madara's rinnegan, obito appears to have black rods emerging from his mokuton. What's going on? I think obito might not be producing the black rods, might just be dirty clean up by the scanners. Dark wood perhaps?
Perhaps the black rods are hashirama's "black wood", in the vein of sasuke's "black flame/amaterasu" or darui's "black lightning". Either way, it's pretty elite.
Zetsus are made of Hashirama clone connected to Mazou, but their consciousness are birthed thanks to Madara sharing his mental/spiritual energies with them (he has 3 tubes, one for sending his energies on his head and the rest for sucking chakra ?). That's why, in difference to the Soulless Hashirama Clone, they have a mind of their own.
There are at least 2, or more Zetsus which were used to substitute for Obito's parts (at that point, they were more like Hashirama soulless clones, or so it seems). The Spiral one, whose internal parts were used to substitute for Obito's internal organs (that's why it's empty --->>>) and the Left Sided Zetsu, whose external parts were used to substitute for Obito's skin and muscles(?) around the right side of his body along with half of his arm... or not :P, because that Zetsu mentions that all other are HIS clones (--->>> top right panel), thus he must have been before them, so perhaps his parts are joined with Madara ? Thus it's possible that simply other clones were used to substitute for Obito's limbs.
Obito can use mokutoun without the Zetsu Suit, thanks to his Hashirama's artificial body parts (top panels):
It's probably just not on the level were he can make good enough damage compared to it's chakra cost. The Zetsu Suit most likely strengthens his Mokuton powers, as the Zetsu himself holds some chakra.
What's really strange, is the fact that the Spiral Zetsu was reconnected back to Mazou at some point:
yet they said that Obito, just like them, doesn't need to eat or drink anymore (--->>>). This might be because the Spiral Zetsu gave out too much parts of himself and thus probably had to be relinked with the statue from time to time and perhaps going out with Obito was an one way trip from the beginning... thus explaining why we don't see him anymore ? Or perhaps Madara was giving him special orders through the roots, who knows ?
The rods might have been used to patch up Obito's crushed bones. Plus later on it would allow him to control GM, without it sucking him dry, or so it seems.
The reason for connecting the spiral Zetsu to the Root of the Mazou is this:
Obito borrowed some power from the Mazou as an extra boost, to be able to smash the rock blocking his escape path.