More and more research is being done which proves that growing plants may be the best medicine in the world for improving your mental (as well as physical) well being. They not only add beauty but they've been proven to have calming, stress-reducing, muscle relaxing and spiritual effects upon people. Can't say that for about lot of thing in this world - except perhaps drugs. Plants are healthier.
Dr. Robert Ulrich of Texas A&M University conducted research in which the brain waves of people shown vegetation scenes, water scenes ad urban scenes were measured. Alpha waves were used as a physiological measure of a person's degree of wakeful relaxation. He found that people shown vegetation scenes emitted more alpha waves than people shown either of the other scenes.
This evidence of the relaxing effects of plants was proved as well in a University of Delaware study that measured people's muscular tension. Ulrich concludes that "Aesthetically pleasing interior environments (plants in your home/office) elicited a positive affective state (happiness, for those who can't handle medical-speak) that served as a buffer to stressful tasks and surroundings" (i.e., your work, your boss, your co-workers).
Additional research has shown that plant help to reduce mental fatigue. Stephen Kaplan of the University of Michigan says that mental fatigue comes from straining one's directed attention, this is the ability to force oneself to pay attention to something that is not particularly interesting (like that company meeting about memo structure). This fatigue can cause errors, irritability and/or rash, uncooperative behavior (you see, you're not to blame for being a creep).
Plants to the rescue!! They help people to "get away" and restore oneself from normal surroundings and they fascinate and attract people, breaking up the monotony and boredom created by forced attention. And the extra plus is that the excess oxygen helps perk you up too.