Herbs are very powerful medicines and it is good to see so much research being done on the efficacy of plants as medicine.  Of course herbs used for  medicinal purposes have been used for thousands of years so there has been much case study data collected regarding their varied applications.  The wonderful thing about plants are their many uses.  Take St Johns Wort for example.  It is commonly used for anxiety and depression. However it is also a powerful anti-viral and it is also excellent for viral diseases like chicken pox.   The fresh or dried herb can be used as a poultice or tea.  The same herb can be concentrated in a liquid tincture or a tablet form.