All plants and stones impart vibrations to their environment. A clever decorator's eye will envision how to create an aesthetically pleasing ambiance, while incorporating the elements, symbols, colors etc. whose function are purposeful. Doing just a little investigation, you'll find that the vibratory properties of most things make common sense. Often we read these vibrations automatically, innately. All of the above have symbolic meaning.
Symbols are language, so think twice when using one.
There are no tokens of Wisdom that are designed to incite fear or terror. In and of themselves, they possess no power. We empower them, and because of that they are useful. You would feel ever so secure with one in the front yard. Alas, there is none.