Plant Characteristics That Help Alleviate Human Stress

Depression is a serious human problem, and estimates by the World Health Organization (WHO) indicate that depression affects about 121 million people worldwide.  Fewer than 25% of those affected, however, receive appropriate care due differences in the level and duration of depression, lack of trained health providers, side effects of medications, costs of treatment, social stigmas associated with mental disease, and variation in gender, age, and symptoms among individuals.  Horticulture therapy, the process of utilizing plants and horticultural activities to improve social, educational, psychological, and physical adjustment of body, mind, and spirit, has a history in medicine for rehabilitating and healing.  Yet, the characteristics of plants and plant materials that counter disorders associated with mood changes, burnout, and increased heart rates have not been studied.  To determine plant traits that would exhibit positive effects on individuals, our laboratory recruited university students in a psychology class to view and touch plant materials, ascertaining favored physical characteristics of plants as a suggestion of plant traits that would have positive effects on stressed and depressed patients.  Large-sized, flowering, aromatic plants were more attractive to test subjects than smaller, non-flowering non-aromatic plants.  A follow-up study using computer generated pictures and students in a plant science class demonstrated a preference for colored flowers over white flowers and indecision over robust and simple flower shapes.  All studies had the approval of the University of Massachusetts Office of Human Research Protection.