Native to tropical and subtropical regions of the Americas, passionflower is recognized in particular to help relieve anxiety [Study. Akhondzadeh S Naghavi RH, et al. Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam. J Clin Pharm Ther 2001 October; 26 (5): 363-7. ] .