Cassava root / Tapioca for survival food?

Interesting my wife and I enjoyed bubble green tea tonight and it made me wonder how you make tapioca so I looked it up and it looks like it could be a good survival food to grow although I don't know what environment is needs, sounds like it is native to south America but spread to many places in the world.

It can be used for a lot of things including breads and gelatins.

Tapioca - Wikipedia, the free encyclopedia
"World War II[edit]
During World War II, due to the shortage of food in Southeast Asia, many refugees survived on tapioca. The cassava plant is easily propagated by stem-cutting, grows well in low-nutrient soils, and can be harvested every two months, although it takes ten months to grow to full maturity. The plant provided much needed carbohydrates and other nutrients during wartime.[8]"

 

I remember reading a story many years ago about a Phillipino farmer who was forced to work for the Japanese soldiers and watch them abuse the women etc. After a couple of weeks of this, he made them a special stew of cassava just for the soldiers of unprocessed roots. A few minutes later they were paralized and a couple hours later they were dead. He then put some empty whisky bottles near them and went and told the other soldiers they were dead. They thought that they had died of bad booze, not food. Some varities of cassava are very toxic and need to be processed and you need to know how to do it and to which plants. If you are going to forage in the woods, know your plants as a lot more then mushrooms can kill you.