If the bad influencer has succeeded in persuading the group to 'sack off' their responsibilities, i.e. lectures, deadlines, group meetings, one may exclaim 'The seed has grown into a tree'
Anna: So, tomorrow we reconvene at my house for an all-day no distraction group meeting!
Laura: I want to go to Oceana to seek out some Spice Boys
Mel: DON'T PLANT THE SEED!
Tash: It's already grown into a tree, don't fight it.