Posted: 07/03/2015 at 18:40
I have no problems in taking seeds from gardens, restaurants, garden centres, parks etc. Taking seeds off of plants is normally benign and the odd one that ends up in your pocket is not going to make a difference.
Going out with a shovel and taking a whole plant is clearly different as you are depriving someone of something.
Cuttings are a gray area for me - an overgrown plant and no one will notice but I know some people steal from rare plants and they are literally picked to death, so difficult to give a generic answer.