​Ethnobotany of Acorus in China
2020-01-01 13:08
Ethnobotany of Acorus in China
Acta Societatis Botanicorum Poloniae,2018;87(2):3585.
Hang Shu 1 , Shuang Zhang 1 , Qiyi Lei 1,2 , Jiangju Zhou 2 , Yuanyuan
Ji 1,3 , Binsheng Luo 1 , Liya Hong 1 , Feifei Li 1 , Bo Liu 1,3 , Chunlin
Long 1,3,4 *
1 College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China
2 College of Life and Environmental Sciences, Kaili University, Guizhou 556000, China
3 Key Laboratory for Ethnomedicine (Minzu University of China), Ministry of Education of China,
Beijing 100081, China
4 Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
* Corresponding author. Email: long.chunlin@muc.edu.cn


Abstract
        In China, species in the genus Acorus are used for many different purposes, viz., in traditional medicine, for rituals, and as ornamental plants. Acorus calamus (sweet flag) has been a symbolic plant in Chinese culture for many centuries and is used as a ceremonial object in festivals throughout the country. For other Acorus species in China, ethnobotanical records are few. During field investigations from 2006 to 2017, we interviewed 573 individuals representing ethnic groups such as the Miao, Yao, Buyi, Shui, Tujia, Dong, She, Maonan, Zhuang, Yi, and Han people. Various ethnobotanical approaches were adopted in the field surveys, including key informant interviews, semi-structured interviews, participatory observation, direct observation, etc.. The results have revealed a rich treasure trove of traditional knowledge on Acorus in China. Two species (A. macrospadiceus and A. gramineus) were used by ethnic groups as spices to add flavor to meat. Through the study found that all the species of Acorus had medicinal value, especially A. tatarinowii; deafness, blindness, and digestive disorders were among the conditions commonly treated using these plants. Traditional knowledge of the cultural, ethnomedicinal, and food values of Acorus, based on our recent literature surveys and field investigations in China is presented here. A better understanding of Acorus is vital for conserving the plants and the traditional knowledge associated with them.
Keywords: Acorus calamus; A. gramineus; A. macrospadiceus; A. tatarinowii; ethnomedicine; ethnobotany; Dragon Boat Festival; plant culture

Introduction
        The genus Acorus (Acoraceae) is believed to include several species [1-3]. Based on recent morphological, ecological, phytochemical, and molecular investigations, four species of this genus are currently recognized: Acorus calamus L. (sweet flag, including two varieties), A. tatarinowii Schott, A. gramineus Solander ex Aiton, and A. macrospadiceus (Yamamoto) F. N. Wei and Y. K. Li. Acorus calamus, in particular, has a long history of cultural, medicinal, and culinary uses around the world [4-6]. The sweet flags occur in the wild and are cultivated in many parts of Eurasia and North America, although the exact native range of the genus is still disputed [7]. In some Asian countries, such as Nepal, local people chew the rhizome of A. calamus to treat coughs [8]. In India, the rhizomes are widely used in the treatment of ailments such as epilepsy, mental illness, chronic diarrhea, dysentery, fever, abdominal tumors, kidney and liver troubles, and rheumatism [6]. In the state of Assam in northeastern India, the local people believe A. calamus to be a supernatural plant and that spirits and devils cannot enter it, owing to its odor. They put the rhizome at the four corners of the altar or the entrance to a ritual site [9]. In Japan, Korea, and India, people collect Acorus for use as medicine and wear the rhizome in their hair to maintain overall health [10]. In China, all species in the genus Acorus can be found, and each ethnic minority has accumulated and documented their particular ways of using the plants.
        In Poland, the inner parts of the young shoots of A. calamus have been commonly used as a snack for children, and the plant is widely used in many parts of lowland Poland to decorate houses during Pentecost. In the 18th century, sweets made from A. calamus were very popular in the Polish manor houses [5].
        There are three major traditional festivals in China, namely the Spring Festival, the Dragon Boat Festival, and the Mid-Autumn Festival. People celebrate the Dragon Boat Festival on the fifth day of the fifth month of the lunar calendar. It is also called “Duanwujie,” “Nü’erjie,” “Chang-pujie,” “Duanyangjie,” “Tianzhongjie,” and “Zongzijie” [11], or “Dyn’ng’jit” in Cantonese. During this festival, the Han Chinese and other ethnic groups eat “Zong-zi” (a special food with cultural significance made from sticky rice and other foodstuffs), compete in Dragon Boat racing, go hunting, collect herbal medicines, wear colorful ribbons, and hang “Chang-pu” (A. calamus) with “Ai” (Artemisia argyi) on the door. The Dragon Boat Festival has been celebrated for some 4,000-5,000 years. There are various explanations for its origin, but the most commonly accepted version is that it commemorates Qu Yuan. Qu was a great poet in the Chu Kingdom during the Warring States period (339-278 BC) and is well-known in China for his patriotic spirit [12]. However, Chinese scholars who recently investigated the initial purpose of the Dragon Boat Festival conclude that it was to pray for health and longevity [13], and this is consistent with the role of medicinal herbs during this festival. Unsurprisingly, in China and other Asian countries, Acorus has become an important symbol of the Dragon Boat Festival.
        Acorus was previously placed within the family Araceae, but now it is placed in its own family Acoraceae, under the order Acorales [14], and is regarded as a member of the oldest extant lineage of monocotyledons [15]. The name ‘acorus’ is derived from the Greek word ‘acoron,’ a name used by Dioscorides, which in turn was derived from ‘coreon,’ meaning ‘pupil,’ because it was used in herbal medicine to treat inflammation of the eyes [4,16].
        In China, A. calamus L., or sweet flag, is called “Chang-pu” or “Shui Chang-pu.” It is a semi-evergreen perennial hairless herb with aromatic leaves that can grow up to 2 m height. The plant has a creeping rhizome, which is extensively branched and up to 3 cm in diameter. Internally, the rhizomes are whitish pink in color and pleasantly aromatic, smelling of citrus, with a bitter taste [4]. Each leaf has an obvious midrib. Flowers of A. calamus are dioecious, having both male and female organs, and are pollinated by insects [17]. This species is found in the northern temperate and subtropical regions of Asia, North America, and Europe, and is widely distributed in most provinces of China. It lives in aquatic environments: wetlands, shallow water, pond edges, and islands below 2600 m above sea level [18].
A. tatarinowii Schott is called “Shi Chang-pu” in China. It is similar to A. calamus morphologically but is smaller, and the leaf lacks a midrib. The rhizomes are more branched than in A. calamus, and the rhizomes (0.2 – 1.0 cm) are smaller in diameter [19]. It has an epiphytic habit and is distributed to the south of the Yellow River watershed in China. It grows at elevations of 20 m−2000 m in wetlands, on banks or among stones of brooks with clear water, and thrives on vertical slopes exposed to torrents. The leaves and rhizomes are aromatic, and it is commonly used in traditional Chinese medicine. In addition, it is often cultivated as an ornamental plant in indoors and large gardens.
        A. gramineus Solander ex Aiton is known as “Jin Xian-pu” or “Jin Qian-pu.” Its leaves are short and slim, and the rhizomes are similar to those of A. tatarinowii, with even more nodes and branches. It is also aromatic and distributed in southern and southwestern China. A. gramineus is not an aquatic plant, but grows in wet and semi-shady environments below 1800 m. It is often cultivated as an ornamental and edible plant in rooms and gardens [20].
        Although A. macrospadiceus (Yamamoto) F. N. Wei is a terrestrial herb with rhizomes, it sometimes grows in wetlands. It is called “Shan-nai” or “Shannai Chang-pu” or “Gourou-xiang” by local ethnic groups including the Miao, Dong, Yao, Shui, and Han Chinese. The plant has a strong fennel-like smell, and indigenous people in southwest China use it as an aromatic herb in cooking. A. macrospadiceus occurs in the mountainous areas of Guizhou, Guangxi, Sichuan, Chongqing, Hunan, and Hainan provinces at an elevation of 400–1200 m above sea level, and is also grown in home gardens.
        Acorus species not only have multiple medicinal, nutritive, and aesthetic uses, they also have cultural, economic, and ecological value. China is unique in having all four Acorus species, but very little ethnobotanical information about Acorus has been systemically documented till date. The objective of this study is to record traditional knowledge about Acorus in China, especially among the communities of minority ethnic groups. 

Materials and Methods
Literature study
        Acorus is an important plant group in Chinese history and a large number of records are found in ancient writings. Collections at the National Library of China, were frequently accessed and books from ancient to recent times were examined. Information on the flora from every province of China, together with Flora Republicae Popularis Sinicae (Chinese version) and Flora of China (English version) have been intensively studied.
        Information in the databases PubMed, Scopus, Web of Science (WoS), and Google Scholar, as well as in that generated by a combined search of available literature in Scopus and WoS have been studied. We have also accessed Chinese databases including WP (China Science and Technology Journal Database) and CNKI (China National Knowledge Infrastructure).
Field surveys
        Ethnobotanical investigations were carried out 24 times from March 2006 to June 2017, covering all four seasons. The areas selected for study were places where the local people frequently use Acorus species, and included several provinces of southwestern China. Guizhou Province, Hubei Province, the Municipality of Chongqing, Guangxi Zhuang Autonomous Region, Yunnan Province, and Hunan Province were visited during extensive investigations into the uses of Acorus. Other provinces surveyed in detail included Sichuan, Tibet, Zhejiang, Anhui, Jiangsu, Fujian, and Taiwan (Fig. 1).
  Fig. 1 Provinces where the ethnobotanical uses of Acorus were investigated

        In every study area, we randomly selected two to five villages or local markets and interviewed five to 12 people who had traditional knowledge about Acorus. A total of 573 informants, including 262 males and 311 females between 14 and 96 years old, were interviewed. Informants were drawn from the following ethnic groups: Miao, Yao, Buyi, Shui, Tujia, Dong, She, Maonan, Zhuang, and Yi, as well as the Han people, who form the ethnic majority in China. Information about the study areas is given in Tab. 1. Ethnobotanical data were collected by employing different interview methods (participatory rural appraisal (PRA), direct observation, semi-structured interviews, key informant interviews, individual discussions, and focus group discussions) [21-25]. During our surveys, we recorded the local names, uses, parts used, preparation methods, and other information. Voucher specimens were collected from the various habitats, and examined and identified by the authors. They were deposited in the Herbarium of the Minzu University of China (Beijing).

Results
Cultural value
        The local people we interviewed often regarded Acorus as a sacred and symbolic plant. A few stories recounted that, in ancient times, people considered the fifth day of the fifth month of the lunar calendar (the day of the Dragon Boat Festival) to be the most inauspicious day of the whole year. It was considered to be a day on which evil posed a severe threat to human beings. A baby born on this day would be threatened by evil or illness. Officials would never be promoted if they began their new positions on May 5th. People would be weak if they lived in houses built on this day [23, 24]. Because the leaf of A. calamus is similar in shape to a sword, people believe that the leaves can kill the evil spirits and keep people healthy (Fig. 2).
        “Chang-pu” (A. calamus) is the most frequently used species at the Dragon Boat Festival. Different names for A. calamus, related to the festival, are used by local communities. Apart from “Chang-pu,” other names include: “Shi Chang-pu,” “Puzi,” “Bai-Chang,” or “Da Chang-pu.” People hang the whole plant on the top of their front doors or main gates together with “Ai” (Artemisia argyi) to keep evil away from the house and family, and they pray for safety for anyone taking trips outside the house. Because A. calamus rhizomes are pleasantly aromatic, people put them in small cloth bags, sometimes together with other plants and sometimes alone. It is said that children who wear these cloth bags tied with red string around the neck will not get sick. This custom has been handed down from generation to generation over centuries.
        In China, essential foods for a number of festivals include dumplings, moon cakes, “Tangyuan” (glutinous rice balls), “Zongzi” (a special food with cultural significance made from sticky rice and other ingredients), and “Xionghuang” (realgar) wine. The local people drink “Chang-pu” (Acorus) wine (liquor containing sliced Acorus rhizomes) during the Dragon Boat Festival in southern China. People believe that those who drink the “Chang-pu” wine will be stronger and healthier. Women wash their hair with hot water infused with Acorus leaves to maintain the hair and enjoy good health for a whole year.

Food value
        During our investigations in Guizhou, Chongqing, and Guangxi provinces, people told us that “Shannai” (or “Shannai Chang-pu”) (Acorus macrospadiceus) is quite popular as a flavoring agent in the preparation of meat and fish. Leaves and rhizomes are both used in cooking. “Shannai” is very similar to “Shi Chang-pu” (A. tatarinowii) morphologically. Indeed, taxonomists often treat it as the same species. However, the local people insist that the two species are not the same. They distinguish them by the smell of the leaves and the habitat in which they are found. “Shi Chang-pu” is epiphytic but “Shannai” is terrestrial (Fig. 3 and Fig. 4). People cultivate “Shannai” in flowerpots or home gardens, depending on their living environment (urban or rural). Our interviews revealed that “Shannai” is most commonly used in Guizhou Province and Guangxi Region. In the Municipality of Chongqing, nearly half the local people knew how to use it as a spice; however, in Hubei, Yunnan, and Jiangxi provinces, only a few people mentioned that it was used as a flavoring.
        A. gramineus is also used as a spice in Guizhou, although it is not popular. Nevertheless, some local people said that, when used in cooking, it gave a better flavor than “Shannai” (A. macrospadiceus) (Fig. 5).
                           
 Fig. 2 Acorus calamus in E’shan Yi Autonomous County, Yunnan (Chunlin Long, Nov. 2012) 
Fig. 3 Acorus tatarinowii in Majiang County, Guizhou (Chunlin Long, July 2016)
                        
Fig. 4 Acorus macrospadiceus in a farmer's vegetable garden in Xiushan, Chongqing (Shuang Zhang, Sept. 2014) 
Fig. 5 Acorus gramineus in Qiannan Autonomous Prefecture, Guizhou (Hang Shu, July 2016)
Medicinal value
        The genus Acorus was first recorded as a medicinal plant in the book entitled Shennong’s Classic of Materia Medica, compiled between 200 BC and 200 AD, where it says that Acorus was used to treat deafness, blindness, cramps, and digestive disorders [26]. According to the Compendium of Materia Medica (Chinese Medicinal Herbs), published in 1552 by Shizhen Li (also known as Li Shih-Chen, founder of theory of traditional Chinese medicine), Acorus could prolong life and treat diarrhea. Both A. calamus and A. tatarinowii could be used for medicinal purposes, but the rhizomes with several nodes were reported to be the most effective. This description matches that of A. tatarinowii, which is the species most often used as medicine [27].
        There are 56 ethnic groups in China, including the dominant Han people. Many ethnic groups have their own traditional medicine systems, although some medicinal plants are widely used by different groups. The Miao people, for example, have a rich repertoire of medicinal plant knowledge dating back some 4000−5000 years. Records state that the Miao people used the rhizomes of A. tatarinowii to treat heart disease 900 years ago [28]. A. tatarinowii is also used to treat dysentery, flatulence, and epilepsy now, as it was in the past.
        Acorus has traditionally been used as an herbal medicine by 28 ethnic groups in China (Tab. 2), according to the literature [29-32] and our field surveys. Many ethnic minorities in China have a language that is unique to them. Different names for Acorus used by ethnic peoples are recorded here in Chinese pinyin (phonetic spelling), as shown in Tab. 2.
        All the 29 linguistic groups studied (including Han Chinese) use A. calamus as traditional medicine; 16 use A. tatarinowii; another 16 use A. gramineus; and seven use A. macrospadiceus (Fig.6). Twelve groups use at least three Acorus species, namely Miao, Jingpo, A-Chang, Lisu, Zang (Tibetan), De-Ang, Dai, Hani, Yi, Jinuo, Buyi, and Wa.


Fig. 6 Number of linguistic groups that use different species of Acorus as medicine

        While the rhizome of Acorus is the part most often utilized in treatments, the whole plant, leaves, and inflorescences are also used as medicines. Twenty-one linguistic groups use only the rhizome of A. calamus; two groups use the rhizome and leaves (Bulang and Lahu groups); two groups use the rhizome and the whole plant (Zhuang and Chaoxian groups); the Tujia use only the whole plant, and the Mulao use only the inflorescence. The most frequently used part of A. tatarinowii is again the rhizome. Seven linguistic groups use the rhizome of A. tatarinowii; three groups use the whole plant; five groups use the rhizome and the whole plant, and the Jinuo use the rhizome and leaves. With respect to A. gramineus, 11 linguistic groups use the rhizome, three groups use the whole plant, and the Dai and Yi people use the rhizome and the whole plant in treatments. Only four linguistic groups use the rhizome or whole plant of A. macrospadiceus as ethnomedicine (Fig. 7).

Non-medicinal uses in China
        According to our field investigations, ethnomedicine is not the only use for Acorus in China. Some ethnic groups, such as the Atayal in Taiwan and the Yao in Hunan, wear Acorus bracelets or necklaces. They cut the thick rhizomes of A. calamus into sections of 1–1.5 cm long, and air-dry them. Around 15 sections of sweet flag rhizome are strung together with a red thread to make a bracelet or 30 sections for a necklace. The local people wear Acorus bracelets or necklaces not only for decoration but also for keeping away insects or evil forces.
        It is common for people to grow Acorus plants as ornamentals [20]. The local people in southern China like to cultivate A. tatarinowii in their villages and home gardens, and on roadsides, for aesthetic purposes. In eastern Guizhou and western Hunan, for example, the Miao people collect A. tatarinowii to decorate urban landscapes and gardens. Since ancient times, Chinese intellectuals and poets have made bonsais out of A. gramineus and kept them in their studies. The tiny, elegant A. gramineus bonsais are still fashionable in urban and some rural areas as indoor ornamentals (Fig. 8).
        In some villages we studied, the local people cultivated A. calamus or A. tatarinowii to clean up water in ponds or drainage channels. Some ethnic groups (such as Yao and Miao) used A. calamus as an insect repellent, especially for mosquitoes. The fiber from dry leaves of A. calamus had been used for different purposes. For example, the “Zong-zi” can be tied with sweet flag leaves.



Fig. 7 Number of linguistic groups who use different parts of Acorus as ethnomedicine

Fig. 8 Bonsai with Acorus gramineus used as decoration
(Chunlin Long, Beijing, March 2017)
Discussion
        The diverse climate and geography, varied terrain, and range of soil types of China harbor an enormous diversity of plants, with 31,142 species of higher plants alone. Over thousands of years, the Chinese have accumulated a rich and valuable trove of traditional knowledge about the use of plants [33]. In China, according to our field surveys and information in the historical records and available literature, plants in the Acorus genus have important cultural, medicinal, and nutritive value, and deserve more attention, as such.
        In the Compendium of Materia Medica, Shizhen Li recorded five species of Acorus and Chinese scholars have described some new species in recent decades. Currently, seven species and two varieties of Acorus are recognized. While Flora Republicae Popularis Sinicae recognizes four species (A. calamus, A. tatarinowii, A. gramineus and A. rumphianus), the Flora of China and the Plant List recognizes two species only (namely A. calamus and A. gramineus). In the Plant List (http://www.theplantlist.org/), A. tatarinowii is regarded as a variety of A. calamus, (A. calamus var. angustatus Besser), and A. spadiceus as a variety of A. gramineus (A. spadiceus var. angustatus Besser). However, many scientific publications still make the distinction between the four taxa discussed in this paper, and we have followed this classification.  In some Chinese historical sources, “Shi Chang-pu” was regarded as the most effective medicinal Acorus. From our investigations, we concluded that it was probably a general name for all medicinal Acorus. A taxonomic revision of Acorus will be required to ensure that the Acorus obtained for medicinal purposes comes from the right sources and institute quality control for Acorus medicine.
        According to our field surveys and literature records (Tab. 2), A. calamus, A. tatarinowii, and A. gramineus are referred to most often as the species with medicinal value. However, modern pharmacological research has mainly focused on two species, namely A. calamus and A. tatarinowii. Few researchers have studied A. gramineus or A. macrospadiceus.
        In this study, we found that only the Mulao people collected inflorescences to treat wound. But, up till now, there has been no research on the chemical components or pharmacological activities of the Acorus inflorescence. Further studies may help elucidate the process by which the Acorus inflorescence can assist with wound-healing.
        Our field surveys in China revealed a rich trove of traditional knowledge about Acorus across the nation, and A. calamus certainly plays a significant cultural role during the Dragon Boat Festival. Unfortunately, only a few young people in our field sites knew about the use of Acorus in traditional medicine. Indeed, the traditional knowledge about the medicinal properties of Acorus that is described in the literature and historical sources seems to be disappearing. Most of the folk healers are aged, and cannot transfer their knowledge to the next generation because of emigration of young work force to urban areas. There is a need to conserve and pass down traditional lore in local communities.
        “Shannai” (A. macrospadiceus) is a popular spice in Guizhou, Guangxi, and surrounding areas, where it is added to meat and fish dishes. It is a widely used every-day ingredient because of the way it enhances the flavor of food. During our field surveys, at least seven ethnic groups and some Han Chinese said they frequently collected A. macrospadiceus to use for cooking. The chemical and pharmacological properties of this species should be studied to increase understanding of its traditional applications.

Conclusions
        During a long-term study of Acorus over the past 12 years, we have collected a body of ethnobotanical information on Acorus in China. We found that Chinese people from 29 linguistic groups have a long tradition of using four Acorus species, namely A. calamus, A. tatarinowii, A. gramineus, and A. macrospadiceus. They have utilized Acorus for medicinal, nutritive, cultural, ornamental, and ecological purposes. This study reveals that southwestern China, where different linguistic groups have a rich trove of knowledge about all Acorus species, is the knowledge center for Acorus. Recognition, cultivation, trading, and application of Acorus macrospadiceus in Guizhou and its surrounding areas indicates the local people’s wisdom. Further phytochemical and pharmacological studies on A. macrospadiceus will be essential for resource management and sustainable use. Results from our study also show that transmission of knowledge about Acorus between generations is now much reduced, although all linguistic groups are still treating A. calamus as a culturally symbolic plant during the Dragon Boat Festival. The young people in local communities know little about the medicinal uses of Acorus, which had been common knowledge for traditional healers and villagers for many centuries. Given China’s accelerating economic development, the documentation and conservation of the traditional knowledge of plants such as Acorus are now urgent, especially in remote areas such as in southwest China's ethnic villages.

Acknowledgments
        Dr. Peter Matthews, an ethnobotanist and anthropologist at the National Museum of Ethnology, Japan, edited the English and provided useful comments. We are thankful to the local people for their assistance in the field investigations and for sharing their valuable knowledge. Friends nationwide helped to collect information, voucher specimens, and samples of Acorus. Special thanks go to Keming Liu and Xiuzhen Cai from Hunan Normal University, Dongping Li from Kaili University, Limin Cao from Gannan Normal University, Limin Cao from Hengyang Normal University, and Jiangqun Jin from Chongqing Institute of Medicinal Plant Cultivation. This work was supported by the National Natural Science Foundation of China (31761143001 and 31161140345), the Ministry of Science and Technology of China (2012FY110300), Minzu University of China (Collaborative Innovation Center for Ethnic Minority Development, YLDXXK201819), Ministry of Education of China, and State Administration of Foreign Experts Affairs of China (B08044).

Authors’ contributions
        CLL designed the study. CLL, SZ, HS, YYJ, QYL, JJZ, LYH, FFL, and BL performed the field investigations. SZ and HS drafted the manuscript and contributed equally to this work. CLL revised and finalized the manuscript. All authors read and approved the final manuscript.

Conflicts of interest
        The authors declare no conflicts of interest.

 
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