If people find Marijuana seeds in their bag of green, what are the benefits of planting around the city?

Question

supposing it were legal in that city

Answer 1

one lot of happy hobos!

Answer 2

If we planted the Cannabis plant around all the cities of the earth, it could significatly help in the fight against excess Carbon Dioxide.  Marijuana plants grow very fast and their leaves have a very large surface area.  This enables the plant to have a very large intake of carbon and also output of oxygen.  Aside from the pollution levels dropping, cities would look and smell nicer.