Dan Shen. A most important herb in Chinese medicine. Traditionally used to stabilize the heart, calm the nerves and to lighten stagnant blood. The roots are effective against angina pectoris and phlebitis. Reduces blood pressure, improves circulation by dilating the blood vessels and reduces blood cholesterol. Useful for palpitations, irritability and insomnia. The plant forms a pretty rosette and sends up a spike of blue flowers. The roots are a distinctive bright red and are dug in the Fall. Perennial. Hardy to zone 9.