Nice game, addictive, I kept playing and reading the journal. Game gets extra points for being based on actual mushrooms and facts in the journal.
And this caught me by surprise - the final upgrade is a playable retro mini-game version of the game!
Also the ant based fungus has elaborate and unique animation which goes above and beyond considering how deep it is into the game.
Only suggestion for improvement I would make, and I don't know exactly how to do this, is to give the player something to do while waiting for mushrooms to grow.