The most widely used & researched herb for depression
John's wort. The cochrane review of 29 research studies found it to work as well as pharmaceuticals with less side effects. It may be less effective in severe depression, but so are pharmaceuticals. See www.Sciencedaily.Com/releases/2008/10/081007192435.Htm.
Another herb that often helps is rhodiola rosea. Please see comment for more:.