Moxa - Facts of Mugwort Leaves

Nowadays moxibustion has been a popular nature therapy in Europe. The raw material of moxa is mugwort leaves. The knowledge of mugwort leaves may be helpful for you to choose moxa products. This article refers the research results from Professor Wan Dingrong and his team, detailedly telling the facts of mugwort leaves. Whether you are a moxibustion therapist, a moxibustion enthusiast, a seller of moxa products or a maker of moxa products, the article is worth reading.

Table of contents:

1) Moxa in East Asia

2) Mugwort in traditional Chinese culture

3) Qiai, mugwort of Qichun, represents high quality moxa

4) The best time to pick mugwort leaves

5) How to dry mugwort leaves in a traditional way

6) Three-year moxa for seven-year illness

Moxa in East Asia

In the sixth century AD, the Liang Dynasty of China showed its great cultural attraction to the Korean peninsula and Japan. Moxibustion is thought to be one of Chinese techniques introduced to Korea and Japan at that time. The old therapy plays an important role in traditional medicine of Korea and Japan. In Europe, there are moxa products from China, Japan and South Korea.

In South Korea, the standard sources of mugwort leaves include Artemisia argyi, Artemisia princeps and Artemisia montana. In Japan, the standard sources of mugwort leaves are Artemisia princeps and Artemisia montana. In mainland China, Hong Kong and Taiwan, the only standard source of mugwort leaves is Artemisia argyi. Artemisia indica is also used as a source of mugwort leaves in some provinces of China.

Mugwort in traditional Chinese culture

Mugwort is a widespread plant in China. It is not only a herb, but also is a cultural symbol.

Around the Qingming Festival, which is April 4th or 5th, southern Chinese people make a kind of food named “green balls”, which main ingredient is glutinous rice. The color of green balls is traditionally from green shoots of mugwort.

The fifth day of the fifth lunar month is the Duanwu Festival. The day means the coming of summer which is a season with various pathogenic factors including heat, dampness and insects. Around this day, a bunch of mugwort and sweet flag always appears on the entry of every Chinese residence. The pleasant herbal smell of the plants enhance people’s confidence in preventing diseases.

Qiai, mugwort of Qichun, represents high quality moxa

For festivals, people always use mugwort leaves picked in their hometown. But for medical use, raw material from a specific area is always preferred. Before the 13th century, mugwort leaves from Tangyin of Henan province or Ningbo of Zhejiang province once meant high quality. For recent hundreds of years, mugwort leaves from Qichun of Hubei province have been acknowledged to have the best quality. According to the investigation of Chinese researchers, the levels of volatile oil, flavonoids and tannin in mugwort leaves from Qichun are much more than those of mugwort leaves from other areas. Mugwort of Qichun, which is named Artemisia argyi cv. Qiai, is recognized as a cultivar.

Even in Qichun, different planting environments may influence the quality of mugwort leaves. Full sun and weak acidic damp soil increase the levels of flavonoids, tannin and organic acids, making mugwort leaves more suitable for medical use. Decrease of sunlight and water increases the level of volatile oil, benefiting the production of essential oil.

A big problem of modern TCM is the overuse of chemical fertilizer, which severely harms the quality of herbs. NPK compound fertilizer boosts the yield of mugwort leaves as well as increases the level of volatile oil, but the levels of flavonoids and tannin are greatly reduced. Organic fertilizer has similar but slightly smaller influence.

The best time to pick mugwort leaves

Traditionally people think that the days around the Duanwu Festival is the best time to pick mugwort leaves. The fifth day of the fifth lunar month is between the end of May and late June. According to the investigation of Chinese researchers, the best time to pick mugwort leaves is early June. At the time, mugwort leaves have the highest levels of volatile oil, flavonoids and tannin as well as the biggest yield.

In ancient times, herbs were always picked from wild plants. In late 19th century Chinese population was about 400 million. Nowadays Chinese population has been over 1.4 billion. The domestic consumption of herbs is greatly increased. Herbs are also exported to foreign countries. Therefore, in order to satisfy market demand for the amount of herbs, the frequency of picking herbs is more than the past.

Now the growers of herbs may pick mugwort leaves three times a year. The first time of picking is in early June, the second time of picking is in early autumn, and the third time of picking is in early winter. According to the investigation of Chinese researchers, mugwort leaves picked in early June have the highest levels of volatile oil, flavonoids and tannin. However, mugwort leaves picked in early autumn have the highest heat of combustion, allowing them to be a reliable source for satisfying market demand for moxa products.

How to dry mugwort leaves in a traditional way

Traditionally mugwort leaves are dried in the sun or in the shade. According to the investigation of Chinese researchers, the levels of volatile oil, flavonoids, tannin and organic acids of mugwort leaves dried in the shade are significantly higher than those of mugwort leaves dried in the sun. This means drying in the shade guarantees the medicinal quality of mugwort leaves used as a herb. The heat of combustion of mugwort leaves dried in the shade is slightly higher than those of mugwort leaves dried in the sun, which shows drying in the sun or in the shade doesn’t have much different influence for the moxibustion quality of mugwort leaves used as the raw material of moxa products.

According to the experience of some makers of moxa products, it is not practicable to dry a large number of mugwort leaves completely in the shade. In the south of China, the wet weather may make mugwort leaves become mildewed. So drying in the sun is a fast and safe way for the makers of moxa products.

Three-year moxa for seven-year illness

The most well-known word about moxibustion was from Mencius, a great thinker of ancient China. Mencius said, “Nowadays some monarchs want to be a great king, which is like seeking three-year moxa for seven-year illness. If there is no reserve, you will be unable to get it all along.”Mugwort leaves should be stored for a long time before they are made into moxa. In the theory of Traditional Chinese Medicine, the procedure is to weaken the dry and violent nature of mugwort leaves, so the burning of moxa will be gentle without harmful effects.

According to the investigation of Chinese researchers, the level of volatile oil declines by an average of 26.5% after storing in a closed environment for one year, declines by an average of 32.5% after two years, and declines by an average of 34.9% after three years. The levels of flavonoids and tannin decline by an average of 49.3% and 46.7% after four years. The composition of volatile oil also has significant changes after long-term storage.

When mugwort leaves are used as a herb, it is obvious that long-term storage damages its medicinal quality. For the use of moxibustion, in the opinion of Chinese researchers, “long-term storage may not always be right".

Reference:

WAN Dingrong, WU Juan, PU Rui, et al. A survey of identification, quality and international standard of Artemisia argyi leaf [J]. Journal of South-Central University for Nationalities (Natural Science Edition), 2020, 39 (4): 362-369.