 The dandelion is also one of several species which break up hardpan in overly cultivated fields, helping crops grow deeper root systems.Some garden flowers originated as weeds in cultivated fields and have been selectively bred for their garden-worthy flowers or foliage.An example of a crop weed that is grown in gardens is the corncockle, ("Agrostemma githago"), which was a common weed in European wheat fields, but is now sometimes grown as a garden plant.