A weed is just a plant that is growing in the wrong place! Almost everything I can think of has a use and is necessary in terms of habitat, food or healing properties. We choose not to have certain things in our gardens and if they insist on growing anyway we call them weeds. Primroses look wonderful growing wild, they are like a carpet of pale lemon in spring. They grow wild across UK but I have seen loads in Cornwall. The ones we grow in our gardens are a different cultivated type with stronger colours and less delicate flowers.