Reminds me of the first few seasons of the CBS show "Survivor". Intially the show provided a meager anmount of rice, and the contestants were supposed for live off the land. I read they were given instructions on what food sources were naturally availble in the area. Those people were starving so bad at the end of only 3 weeks they were loosing hair in clumps, could barely walk, and were getting ill. After the first few seasons, the show increased the food amounts to keep their contestants alive.
I read a book called "A Land Remembered", and although fictional, it presented a bleak picture for early Florida settlers trying to live off the land, even with a garden and hunting.
I consider native food sources a great supplment, and if worse came to worse would try my hardest to make it work, but I hope I never have to.