As I mentioned last week, when I recently harvested the Yacon, I also dug up a Queensland arrowroot (Canna edulis) tuber to try.
I bought and planted the edible canna last year, and growth-wise it has behaved exactly like my ornamental cannas. It has the typical fleshy leaves, has grown to around 2 metres tall and is slowing spreading sideways via new rhizomes.
It is eaten cooked, and is supposed to taste a little like baked potato. I peeled and baked the rhizome I dug up, along with other some other root vegies, with salt and pepper and a little oil.
We did think it was reminiscent of potatoes, although I found it too starchy for my liking - I have since read that Jerry Coleby-Williams slices and soaks his for fours hours before cooking to remove some of that starch, so that's what I'll be doing next time. I wouldn't rave about it first time around, so I'll reserve judgement for my next go.
The advantage of QLD arrowroot over potatoes is that like ornamental cannas, they tolerate both very damp (even wet) soils and hot, dry soils once established. They are relatively pest-free (certainly, mine don't get the pests that my potatoes do!) and as they are perennials, there's no need to plant, harvest, store and replant - you just leave them alone until you need a rhizome when you dig up some of the fresh (old ones can be fibrous) side shoots and cook them.
My ornamentals are as tough as old boots; I wrench them out of the ground, whack them back in somewhere else in the garden and they grow faithfully every time. Survival foods expert Isabel Shipard, talks about them on her website here, where she also describes how to make Arrowroot flour from the high-carbohydrate tubers.
Quite a valuable plant.