Who determines whether a plant is a weed or a real plant?

Answer

Dear Ingrid,

I think this is determined by the utility function that the plant fulfills for a particular person. If it is unwanted, it is considered a weed. For example, the blackberry that you grow for the fruit has a useful function for you. However, if it extends into your neighbor’s garden, it will probably be unwanted there and will be controlled. A large part of our native wild plants also occur spontaneously in our gardens, but most gardeners consider them to be weeds. Other species that are planted as garden plants, such as Japanese Knotweed, escape from gardens and are regarded by nature lovers as weeds (exotics).