Man is the only critter who feels the need to label things as flowers or weeds. – Author Unknown

Plant and your spouse plants with you; weed and you weed alone. – Author Unknown

We can in fact only define a weed, mutatis mutandis, in terms of the well-known definition of dirt – as matter out of place. What we call a weed is in fact merely a plant growing where we do not want it. – E.J. Salisbury, The Living Garden, 1935

What is a weed? I have heard it said that there are sixty definitions. For me, a weed is a plant out of place. – Donald Culross Peattie