So, this world I've got in my head is inhabited by plant-beings, all of whom are constantly connected to the Garden, a kind of physical heaven, through an all encompassing web of roots, tree brains, and access points akin to our own internet. Life can be sedentary and connected directly to the roots (like a PC connected by an Ethernet cable), mobile and connected remotely to access points (like a smartphone), or migratory and connected to both on and off (like a laptop). The tree brains are like routers and switches and send the network information where it needs to go. These are not sentient beings and cannot connect to the Garden themselves, but are still alive. Kind of like how people think animals don't have souls (which is dumb because my dogs definitely have souls y'all).
So, big natural worldwide internet. How would this happen? Why would the world evolve into this kind of ecosystem?
I was thinking that the God Tree was the first being to obtain a form of proto-sentience and got bored, so it started spawning new life to connect to like a toddler's brain making new neural pathways and getting ever more complex. I'll word that more elegantly later :P
I would prefer scientific and pseudo-realistic answers, but if you have a mythological answer (like "Legends tell of a...") or a magical one (like "Wizard dude goes bonkers") I'd appreciate that too.