Been there,done that..All that happened was a lot of areas got mowed for the first time in history.
The local authorities were not impressed when the local courthouse and police station were over-run with pot.(There was actually a seedling that survived for a couple of weeks in the courthouse garden.It made it to about 18 inches high before it became too obvious and it disappeared.)The laughter of passer-byes in the know probably gave the game away..I know I giggled every time I looked at it...
They really made a mess of the local parks and gardens trying to get rid of my babies.
The only upside was that the cops were so busy pulling up seedlings everywhere around town that no-one got busted for about 3 weeks..
I've also heard that a lot of animals like to eat the cannibus plant. That doesn't strike me as a bad thing, however.
Of course, I wouldn't put it past the government to poison the plants, whether it kills animals or not, just to act like they're putting on a drug war. They did it with other plants...