I agree with other listers that the name is choumollier, referred to as chou.  The description is quite accurate, a tall plant with a sweet succulent core to the stem.  We used to steal a plant as we walked home from school and eat the core.  My memory is that it was very similar to the core of a green broccoli stem, which I still like to peel and eat raw (same brassica family).  It was grown a lot in Southland - in the North Island maize seems to fulfil a similar need for cattle fodder. Mary