Medicinal Plants Home > Photos > Medicinal Plants Red flower of Bitterwood or Quassia is Thai herb. The properties of the root is to help fever and aid digestion. Stock Free Red flower of Bitterwood or Quassia is Thai herb. The properties of the root is to help fever and aid digestion. Stock Free Pink flowers of spotted nettle Lamium maculatum. Medicinal plants in the garden. Purple flowering plants gather on a summer day. Horizontal frame. Stock Free