Board Thread:Wiki Discussions/@comment-25050491-20140611171717/@comment-24479616-20140612195157

well we could assume that plant DNA stems from Jubi which is essentially a living tree. Initial form of Chakra = having energy from Shinju-fruit inside oneself, Jubi = Natural energy, so the effect could originally be something like a sage transformation? (kaguyas and hagoromos horns, white skin, chakra cloak and dojutsu). in the next generation, the power split into two (yin and yang): asura = 'body' of jubi (wood release + senjutsu), indra = 'eyes' of Jubi (rinnegan/sharingan + maybe byakugan)

or hashirama was just a plant mutant from eating too much vegetables :P