By Charley
United Kingdom 
a plant that grows to 6ft high and has a tuber just under the soil .the tuber is a creamy colour like a new potato but is more nobley . what is it please .
8 Mar, 2014
Answers
could be Jerusalem artichoke though 6ft seems a bit tall.
with out more of a description it could be a few things.
Thought of one of the hogweed types that have a carrot/parsnip type root.
8 Mar, 2014
Canna can grow to 6ft and the rhizome looks rather like a potato-ish, if you squint your eyes.
8 Mar, 2014
Could be an iris, hedychium (ornamental ginger) is another. What are the leaves like, does it flower, are the leaves aromatic when crushed ?
8 Mar, 2014