Kim Knight meets the man who his way around New Zealand's forests.

The New Zealand bush is an acquired taste. Bitter, sweet, nutty - and turpentine.

"Very turpentine," says Robert Vennell, the softly spoken boy scout of a man who can make coffee from karamū and personally vouches for the diarrhoea-busting power of koromiko.

"Nothing tastes great, if I'm going to be totally honest ... but you can sort of acquire the taste if you persevere. I try to remind myself that a lot of plants are not necessarily nice if you just grab a handful and munch on them.