Great post. Thank you for this valuable info. I suspect that you are right on about being able to ID weeds, however, I also suspect that, when things get that bad, people will resort to cannibalism. So, meeting our neighbors & forming alliances ahead of time could be useful too.
I would hope better for mankind than cannibalism. There are about 10% of men that I could see resorting to this type of behavior but I tend to believe that most of us will do what they do in other countries have starving populations and just die. My option would be to grow a garden, pick weeds to eat, or even die before becoming a cannibal.