This has been bothering me for awhile. Maokai has nothing but contempt for mortals, their reckless magic, and their meddling in the affairs of the forest. It stands to reason then that a creature born with complete disregard for mortal conventions wouldn't have had a name to begin with, and certainly wouldn't have named himself.

So... who did?

The League?

Maokai

I am Oak

mind = blown

exactly why couldnt he have named himself? clearly he's aware of all that he used to be, which means that at some level, he had a consciousness as a tree. anything with a consciousness has the ability to identify itself. now that he has the ability to talk, he turned that identity into a name summoners could use. seems simple enough