Z Weed is a new type of marijuana that first appeared in Season 2 episode 3.
It is rumored to have it's origin from a lab in Minneapolis.
Z Weed is grown using zombie corpses as compost.
A gang called Zeros seems to be the leaders of those willing to selling it to the people of the apocalypse.
A batch of it is rumored to have anti-zombie properties.
Russell Hodgkinson "Doc" came up with the idea and name of Z-weed before season 2 started filming.