Board Thread:Naruto Discussions/@comment-1411686-20140713052356/@comment-25065646-20140714120858

That is cause the plant-flesh/Zetsu mass works biologically different from humans: It doesn't need organs, bones, muscles, skin and stuff, all the cells just fulfill the same vital functions (they just 'live' for the sake of it) without cell specialization - thats why all body parts look exactly the same (white stuff), and the actual shape of the zetsu is irrelevant, the white thing can form anything from venus flytraps to underground roots or even merging many zetsu bodies...