Grain substitute tree crop for subtropics

Hi everyone, is there perennial substitute for annual grains in terms of flour making and carbohydrates. Are acorns and chestnuts only temperate climate crops?

Southeast Asia uses jackfruit as a starchy vegetable, I think. Not as flour though. it is a tree. I don't know if it would grow in subtropics / Punjab, or if it's more really only tropical.

There must be other types of nuts that can grow in your region, not just chestnuts and acorns.

I've seen taro growing in Himalayan foothills in India, including in nice polycultures. It is a starchy carbohydrate source, but not a tree at all.