Well Senpou is usually a jutsu enhanced by Senjutsu, so even if he doesn´t say Mokuton it´s likely still being used. Those gates do look like they´re made of wood after all, just terribly durable wood.......
Though off-topic I´d wish Madara also conjured a couple of clones to wreak some havoc in the field, as he might have wished to hasten the defeat of the Alliance forces so he could have his favorite opponent all to himself heheheh. Though now that I think of it, I wonder if Hashirama would use those Myoujinmon gates to try and restrict Madara's huge Susano'o...
