According to the Harvard University Home Ecology of Flowers Study, upon viewing fresh flowers (particularly during early morning), one will have lower level of anxiety and depression... Further studies show that women who keep flowers at home are less anxious and feel happier besides having increased level of energy to get through the day... 

April 2005 Rutgers University study shows that flowers bring about positive, happy emotions and a general sense of well-being about life... Study participants reported feeling "excited" upon receiving a delivery of fresh flowers, and had displays of immense satisfaction... The study also reported that among study participants, flower recipients had an increased number of intimate connections with family members and friends... It concluded that flowers enhance an individual's emotional well-being and spurs an increase in happiness... 

*source: http://www.ehow.com/list_5904063_benefits-flowers.html