Cloning is basically when a cell is extracted from an organisim, and injected into another so that organsim looks exactly the same as the first. Well if this is so, the cells of a plant would not...
Human cloning is very controversial in the world, some people think it is wrong. Animal cloning is less controversial, but like animal testing of shampoos etc., some people are against it.
Because plants have many more stem cells, not only at meristems, regions of growth where unspecialised cells are actively dividing, but all through the plant. Adult cells easily revert to stem cells...