@Riot: I think these plants could work, but not in the way that was suggested
As a built in mechanic for the jungle the plants seem pretty boring and like they wouldn't really be something you could reliable form strategies around, not sure if that's the point, though forcing junglers into a reactionary position doesn't seem like the best thing for the experience of those players.
In any case I don't really like the idea of them being built into summoners rift, but I think it could be absolutely amazing as a passive ability for a supportive type jungler. Here's how I see it working, after killing a certain amount of large monsters(maybe also siege minions to allow them more viability in lane) this champion could be rewarded with a seed, which could be planted at certain locations around the map for varying effects, plants in the river could offer the heal/slow, or to create the satchel charges or vision plants near brush or objectives(could have coloured areas on the ground to denote which plant would grow if a seed was planted there). More plant types could be added but each would take a certain amount of time to grow after being planted, and would be visible on the mini map to both teams, giving the same potential benefits to members of either team, meaning the player planting them would need to be careful where they placed each plant or could potentially use them to even bait in enemy players.
By giving control over the plants spawn locations to a specific player and removing the random elements this could feel a lot more rewarding to play with or against. Alternatively, rather than have this tied to a specific champion it could also work as a passive to a new utility focused item for junglers.