Ethnobotanical study on medicinal plants used by Maonan people in China

Background This paper is based on an ethnobotanical investigation that focused on the traditional medicinal plants used by local Maonan people to treat human diseases in Maonan concentration regions. The Maonan people have relied on traditional medicine since ancient times, especially medicinal plants. The aim of this study is to document medicinal plants used by the Maonans and to report the status of medicinal plants and associated traditional knowledge. Methods Ethnobotanical data were collected from June 2012 to September 2014 in Huanjiang Maonan Autonomous County, northern Guangxi, southwest China. In total, 118 knowledgeable informants were interviewed. Following statistically sampling method, eighteen villages from 5 townships were selected to conduct field investigations. Information was collected through the approache of participatory observation, semi-structured interviews, ranking exercises, key informant interviews, focus group discussions, and participatory rural appraisals. Results A total of 368 medicinal plant species were investigated and documented together with their medicinal uses by the Maonans, most of which were obtained from the wild ecosystems. The plants were used to treat 95 human diseases. Grinding was a widely used method to prepare traditional herbal medicines. There were significant relationships between gender and age, and between gender and informants’ knowledge of medicinal plant use. Deforestation for agricultural purposes was identified as the most destructive factor of medicinal plants, followed by drought and over-harvest. Conclusions The species diversity of medicinal plants used by the Maonans in the study area was very rich. Medicinal plants played a significant role in healing various human disorders in the Maonan communities. However, the conflicts between traditional inheriting system and recent socio-economic changes (and other factors) resulted in the reduction or loss of both medicinal plants and associated indigenous knowledge. Thus, conservation efforts and policies, and innovation of inheriting system are necessary for protecting the medicinal plants and associated indigenous knowledge. Awareness is also needed to be raised among local Maonans focusing on sustainable utilization and management of both medicinal plants and traditional knowledge.


Background
Traditional medicine is used to maintain people's health, as well as to prevent, diagnose, improve or treat physical and mental illnesses all over the world [1,2]. Medicinal plants are believed to be with healing powers, and people have used them for many centuries. Aimed to modern drug discovery, traditional medicinal plants have been studied and developed which is followed the ethnobotanical lead of indigenous cures used by traditional medical systems [3][4][5]. Traditional medicinal knowledge, especially using medicinal plants in the developing countries, has been in existence and use, and has been a part of therapeutic practices [6]. Therefore, the investigation of plants and their uses (especially medicinal purposes) is one of the most primary human concerns and has been practiced in the world [7][8][9][10][11][12].
The traditional use of medicinal plants in China is widely accepted. The population of 55 minorities is 11.2 millions occupying 8% of China's population, and these minorities distribute in 65% of the country's territory. Each minority has its own medicinal characteristic, and has various experiences of medicinal knowledge [13]. Traditional medicinal plants play an important role of protecting people's lives and health in minority regions, especially in remote and poor area [14,15]. Because of unique natural conditions and customs in the ethnic minority areas, long-term practices of using medicinal plants have formed various systems of treating diseases [16][17][18]. For example, Tibetan medicine is famous for treating digestive disorders, rheumatic diseases and wounds [19,20]. The Mongolians have a long history of horse riding, and their medicine is effective to deal with bone fracture and brain concussion. Yao medicine has special advantages in cancers and skin problems [21].
North Guangxi has been recognized as a rich biodiversity and world-famous karst area. With the elevation between 700-1500 m, it is obviously affected by plateau terrain and subtropical monsoon climate. Thus, the temperature difference of four seasons is small but the vertical climate changes significantly. There are more than 10 ethnic groups living in north Guangxi and formed colorful ethnic characteristic. As one of the indigenous minorities, Maonan is mainly living in Huanjiang Maonan Autonomous County, Guangxi Zhuang Autonomous Region, southwest China. The exceptional altitudinal range, topography and climatic variability in this region have fostered a center of plant species endemism. Here the majority of Maonan people rely on medicinal plants for self-medication. The Maonan medicine has made a great contribution to protect the health of local people. This is due to free access to medicinal herbs, cultural traditions and high cost of hospital treatments in the town nearby. Local people widely utilize endemic species, and they have developed their own traditional medicinal knowledge. Without writing language, Maonan people pass on their indigenous knowledge from generation to generation orally. Nowadays, the Maonan children spend most of their time in schools, where they are taught in Han language. This decreases their chances to learn about the uses of the medicinal plants from the old people. Therefore, important information about medicinal plants is easily lost in the transfer process of indigenous knowledge. With the impact of increasing modern health facilities and modern civilization in Maonan area, indigenous knowledge is depleting rapidly. Although a number of ethnobotanical documentations about several ethnic groups have been published during the past decades in China, few field ethnobotanical studies have been conducted in Maonan society. It is therefore necessary to carry out a survey to document the medicinal plants and associated indigenous knowledge in Maonan region.
Thus, the purposes of the present work were as follows: (i) to document and analyze the knowledge and use of medicinal plants by Maonan people at the study area; (ii) to circulate the results within the scientific community in order to open a door for research in other disciplines; (iii) to document the medicinal plants that could be valuable in future's phytochemical and pharmacological discoveries, and (iv) to contribute to the knowledge and conservational possibilities of plant biodiversity, bearing in mind that biological diversity is also related to the use and applications of natural resources.

Study area and the people
The study area covered 18 villages of Huanjiang County (the only Maonan autonomous County in China) in the northern part of Guangxi Zhuang Autonomous Region, southwest China ( Figure 1). The villages are located in 5 townships, which were selected based on Maonan traditional settlements, namely: Chengnan, Chengbei, Luoyang, Shuiyuan, Shangnan, Youdong, Mulun, Xia'nan, Pochuan, Fengyi, Zhongnan, Tangba, Xiatang, Yuhuan, Caimen, Guzhou, Xiyuan, and Jingyang villages. Huanjiang County is situated in the subtropical zone, located between 24°83′ and 25°06′ east longitude and between 107°92′ and 108°2 6′ north latitude, with the annual average temperature of 20°C and annual rain fall of 1500 mm. The vegetation of the county belongs to the subtropical evergreen montane forest. It is humid in summer and relatively dry in winter. The most Maonan villages are seated on the small strips of flat land or slopes in the rocky mountainous area at 500-1000 meters above sea level. The sinkholes and underground caverns in the area have well developed because of karst landform. Despite abundant rainfall, there are no big rivers but only a small number of streams. Water shortage has been a major obstacle to economic and social development in the Maonan areas.
The Maonan minority, with a total population of about 107,200, is one of the 55 officially recognized ethnic groups in China. With no written language [22], the Maonans' stories and traditions are remembered and passed down orally from generation to generation, but these are becoming less and less. The Maonan language belongs to the Dong-Shui branch of the Zhuang-Dong language group in the Chinese-Tibetan language family. The Maonan language is widely spoken in Maonan communities. Almost all of the Maonans know both Han and Zhuang languages, because they need to communicate with the Zhuang and Han people, the majorities in Guangxi. About 60% of the Maonan people live in Huanjiang County, which is the only Maonan autonomous county in China. The Maonans are polytheistic, and they pay homage to dozens of deities or immortals on various occasions. These icons include figures from myths, legends, celebrities of historical events, divinities from Taoism or Buddhism, ancestors of the family and so on [22]. Due to remote mountainous regions and poor economic environment, traditional remedies of medicinal plants are the most important and sometimes the only source of therapeutics in the Maonan villages. The long utilization history and traditional knowledge of medicinal plants had supported their livelihoods. The Maonan healers and farmers have developed their own ethnomedicinal knowledge.

Field works and ethnobotanical data collection
A total of 118 (106 males and 12 females) informants were interviewed in the study area, in which 80 were selected using snowball technique and 38 key informants were selected purposively and systematically based on the recommendations of knowledgeable elders, local authorities and development agents. All of the informants were local inhabitants aged between 21 and 85 years. Local Maonan healers were surely identified as key informants, because they were important custodians and participants of indigenous knowledge of medicinal plants. Interestingly, all these traditional healers were males. A few women were also interviewed to examine their medicinal knowledge and opinions.
Ethnobotanical investigations were carried out to collect data on medicinal plants used to treat human ailments following standard methods in Maonan area. The methodological approaches were semi-structured interviews, field observations, group discussions and guided field walks. The data were collected from June 2012 to September 2014. Interviews and discussions were undertaken based on a checklist of questions prepared in Chinese and translated into Maonan language. Information was carefully recorded during interviews with each informant. Field observations were performed with traditional healers guided on the morphological features and habitats of each medicinal plant species. Voucher specimens of cited medicinal plants were collected and their local identity was reconfirmed by other informants. The information obtained was cross-checked with the other informants. The information such as the local name, habit, wild/ cultivated, availability of medicinal plants, need of conservation and efforts made by inhabitants, and traditional medicinal uses of plants were recorded. Group discussions were conducted on multipurpose, conservation, threats of the medicinal plants, and transferability of knowledge with the healers and local people in the villages. Also, the key informants were selected for preference ranking exercise.

Specimen collection and identification
The listed medicinal plants were collected from field and gardens, and the habits of these plants were recorded. The voucher specimens were made and deposited in the Herbarium, College of Life and Environmental Sciences, Minzu University of China, Beijing, China, for future references. The botanical identities of collected specimens were confirmed by the authors and other taxonomists at Minzu University of China. Plant names were checked with Flora of China and botanical websites (e.g. http://www.tropicos.org/).

Data analysis
The data were summarized using Microsoft Office Excel sheet. Descriptive statistical methods were applied to analyze and summarize the ethnobotanical data such as frequency and percentage.
Preference ranking exercise [23,24] was conducted by 8 key informants on 7 medicinal plants used to treat traumatic injury in the study area. The highest number of medicinal plants was prescribed by informants to fight traumatic injury. The plants in this exercise were shortlisted by the key informants, and then their importance to manage traumatic injury was discussed. The plants were given to the informants and were ranked based on their efficacy. Medicinal plant that was believed to be the most effective was given the highest value 7, and the one with the least effectiveness a value of 1. Rank was determined based on the total score of each species. A total rank of preference exercise was obtained by summing the number of informant given.
The reported ailments were grouped into 21 categories based on the information gathered from the interviewees. Factor of informant consensus (F IC ) was calculated for each category to test the agreements of the informants on the reported cures for the group of diseases. The F IC was calculated as follows: number of use citations in each category (N ur ) minus the number of species used (N t ), and divided by the numbers of use citations in each category minus one [25,26]. The formula was listed as below:

Medicinal plants reported
The study recorded 368 medicinal plant species (see Table 1).  Table 2). The distribution of informants in age, gender and education class was shown in Table 3. The majority of informants interviewed were above 40 years old in this investigation. The male informants were 89.8% and less educated. There was a significant correlation between the informant age and phytomedicinal knowledge.

Life forms, plant parts used, method of collection and administration
The result of life form analysis of medicinal plants showed that herbaceous plants constituted the highest proportion represented by 203 (55.16%) species, while there were 67 (18.21%) shrubs species, 43 (11.68%) lianas and 41 (11.14%) tree species ( Figure 2).
Informants of the study area used different plant parts for preparation of traditional drugs (e.g. leaves, roots, seeds, barks and fruits). The informants reported that more species (153) of medicinal plants were harvested for their whole plants, and these were followed by roots (83), leaves (45), stems (30), fruits (29), tubers (29), rhizomes (27) and 51 other parts (seed, bark, flower and so on) (Figure 3). The majority of remedies were prepared from fresh materials, and some were prepared from either dried or fresh materials while a few were only used from dried materials.

Ranking, informant consensus factor and multipurpose of medicinal plants
Among all ailments in the villages surveyed, traumatic injury was the most commonly disease against which a high number of medicinal plants (67 species) were prescribed. Seven medicinal plant species were used effectively for treating traumatic injury according to key informants. The results revealed Gaultheria leucocarpa was the most preferred medicinal plant, followed by Acanthopanax trifoliatus, and Sargentodoxa cuneata (Table 5). Table 4 gave an overview of the main illness categories. The diseases that were prevalent in the study area had relatively higher F IC values. Medicinal plants to treat certain disease effectively and with reputation in Maonan communities also have higher F IC : traumatic injury and sprain (0.74), fever and malaria (0.73) and infantile diseases (0.75). Moreover, informants indicated the effectiveness of traditional medicines to get relief from certain diseases including traumatic injury, bone fracture, health problems associated with the liver disorder, snake bite, and spider poisoning.
The Maonans naturally relied on plants for multipurpose. Table 6 showed the most frequently inventoried medicinal plants had more functions used by the Maonans in local societies. In addition to medicinal value, most of medicinal plants were also valued for their economic, edible and ornamental values which were considered to serve an  Most of the medicinal plant preparations involved the use of single plant species or a single plant part while those mixing different plants or plant parts were less encountered in the study area excluding those for treating bone fracture, rheumatism and other difficult diseases. Suffering from common diseases (common cold, indigestion, mosquito bite and so on), the Maonans usually picked up some medicinal plants for treatments by themselves. Otherwise, they should turn to the Maonan healers for help, and the local healers usually prepared remedies by mixing various plants or plant parts. Lack of consistency regarding amount of medicines was observed among informants. There was no concise standard in measurement or unit used among the informants.

Threats to medicinal plants and conservation practices
Various factors that were considered as main threats for medicinal plants were recorded by discussion with the informants in the study area. The principal threats of medicinal plants were reported to include drought, deforestation, medicinal purpose, and firewood collection in this area. Informants ranked that the major factors were deforestation for the purpose of agricultural expansion (75%), drought (10%), collection of medicinal plant material (10%) and fire wood (5%). The Maonan people knew the benefits of conserving medicinal plants. However, the effort of conserving medicinal plants was very limited, because most medicinal plants were collected from wild. Even the local healers who frequently made use of medicinal plants for livelihood did not conserve medicinal plants very well, and they preferred to collect them from wild when using for patients.

Medicinal plants and associated traditional knowledge
On the basis of field investigation and literature studies, 368 species of medicinal plants belonged to 295 genera and 115 families were cataloged. Chinese name, scientific name, local name, family name, used parts and the treatment of diseases were listed. Asteraceae (with 24 species) occupied the highest proportion (6.52%), followed by  Fabaceae, Rosaceae and Euphorbiaceae. Moerman also found that species of plants in the sunflower family (Asteraceae) tended to be represented in ethnobotanical usage in excess of what would be expected by their occurrence in local environments [27][28][29]. In contrast, Moerman identified the greater number of families across North America in general. The most widely used plant remedies by the Maonans were obtained from herbaceous species which constituted the highest category of 203 species (55.16%). Similar findings were reported by other studies throughout the world, and the authors reported that people derived their medicine from herbs partly because of the fact that forests had been degraded, and it took less time and effort to harvest plant material from medicinal herbs [6,[30][31][32].
The special geographical environment results in the rich biodiversity of medicinal plants in the study area.   The Maonans have the traditional customs of disease prevention and emphasize on the function of medicinal food in ordinary life. They usually add medicinal plants into food for the purpose of enhancing the body's immunity and disease resistance, such as Talinum paniculatum, Gymnotheca chinensis, Osbeckia opipara and so on. The Maonans have the custom of collecting the medicinal plants for cooking and bathing in dragon-boat festival, such as Acorus calamus, Curcuma longa, Paederia scandens and Leonurus artemisia. They believe that it would be beneficial for their health. This is because many plants matured in the season of dragonboat festival [33].

Preparation, dosage and route of administration of medicinal plants
The most widely harvested part was the whole plant, followed by the roots, leaves, stems and others. The Maonan people used a lot of roots, stems, rhizomes and bark for medicinal purpose. They believed these parts were the most effective. However, such collection of the medicinal plants might kill or damage plants when harvesting. Utilization of leaves might not cause detrimental effect on the plants compared with plant species that root was utilized. Most of medicinal plants were claimed to be prepared from a single species or plant part in the present study, and the different parts of medicinal plant were used to treat disparate diseases. Although Maonan people preferred to treat illnesses with single species, it was observed that the healers mostly used multiple species or plant parts in order to increase the function and efficacy of the drug as they reported during the interviews. Representatively, the Maonan healers mostly used more than one plant species to prepare remedy for treating bone fracture and traumatic injury.
Grinding was the most widely used method of preparation for remedy in the study area. Pounding and powdering fresh plant materials were the other methods of preparation in the study area. Due to the efficiency and richness of the fresh medicinal plants in the study area, preference of application of fresh plant parts was observed. Moreover, internal and skin diseases were more prevalent in the study area. The fresh material use might be an attempt not to lose volatile oils, the concentration of which could decrease on drying. Moa et al. reported that the disadvantage was that utilization of fresh plant parts may threaten the plants through frequent collection including in dry seasons since local people made minimal efforts in storing dried plant material for later use [6].
The Maonans usually use the processing methods such as decoction, medicinal liquor, external application and medicated bath. The way of using herbs was benefit for the popularity in a simple and easy method. They used different additives like alcohol, oil, honey, salt, sugar, eggs, chicken, duck and meat in order to increase the flavor, taste and general acceptability of certain orally administered remedies. Because of poverty, eating animal meat and eggs could increase proteins and might be helpful for body recovery when the Maonans were ill. The Maonan healers considered that alcohol could promote the blood circulation and accelerate the absorption of exudates. In addition, the Maonan healers used different procedures to administer the medicinal plants and alcohol combinations. The medicinal plants were soaked in alcohol for nearly one month and then the patients could drink or applied externally on the affected parts. For example, Acanthopanax gracilistylus, Achyranthes bidentata, Ardisia gigantifolia, Ardisia japonica, Arisaema heterophyllum, Davallia mariesii, Dipsacus asperoides, Drynaria propinqua, Homalomena occulta, Sambucus williamsii, Bauhinia championii, Murraya exotica, and Paris polyphylla were usually soaked in alcohol for treating traumatic injury and bone fracture.

Effectiveness and popularity of medicinal plants
Due to the influence of geography, climate and food culture in Maonan areas, the Maonan healers understood the varieties of diseases, such as traumatic injury, snake bite, hepatitis, respiratory disease, digestive system disease, rheumatoid arthritis, and skin problems. The local people expressed they preferred to use traditional medicines rather than western drugs to get relief from some diseases including bone fracture, health problems associated with the liver, snake bite and those caused by hepatitis. The Maonan healers treated ailments based on the patients' physical conditions, lack of consistency regarding amount of medicines to be used was observed among informants during the interviews. The healers usually did not know which ingredients were important for the therapeutic effect in the multiple prescriptions. The lack of precise dosage was one shortage of traditional medicinal plant uses. Most of Maonan people knew how to use several medicinal plants for treating ailments and health protection. Traditional medicine knowledge was not only in the hands of the Maonan healers and herbalists in the study area. Moreover, Maonan people grew medicinal plants in their home gardens. Plant species maintained by Maonan healers was found to be significantly distinct from plant species managed by farmers. The Maonan healers knew more than 30 medicinal plant species, while most of the non-healers reported less than 15 species. Ethnomedicinal usage of plants managed by healers was remarkably distinct from usage categories managed by farmers. The Maonan healers were reported to use a combination of multiple medicinal plants to treat an illness, but the farmers always used single plant species or a single plant part.

Medicinal plant cultivation and trade
The Maonan people in the study area knew the benefits of conserving medicinal plants. However, the effort of conserving medicinal plants was very limited. For example, only 20.75% of medicinal plants were collected from home gardens, and most of the plants from home gardens were used for foods, spices and substitutes for tea. The majority of medicinal plants were harvested from wild habitats. Even Maonan healers who made use of medicinal plants for a livelihood did not conserve the important medicinal plants in their home gardens, and they preferred to collect them from wild or hidden places when patients visited them. It was explained by informants that local healers did not let the other villagers know the identity of the medicinal plants they were using. Informants further explained that if healers planted the species in their home gardens, they worried that somebody else might recognize them when they were preparing the medicine from the plants. Thus the healers' income would be decreased.
Because of complex terrain and language barrier, the Maonans have been in the traditional self-sufficient agricultural economy in the karst areas. There is a seasonal medicinal market which opens 3 times each month. The sites of purchase and sale of local medicinal plants are located in the town. The medicinal plants grown by farmers were used for household healthcare and little was sold in herbal markets, while medicinal plants were cultivated by healers rarely for trading, either. Not many medicinal plants were solely cultivated for their medicinal purpose, except that the plants were multipurpose ( Table 6). Lack of water and land, most Maonan people would prefer to cultivate foods or cash crops rather than medicinal plants. The other reason was that most medicinal plants were not sold at reasonable prices and therefore not profitable, providing very little incentives for their cultivation. The local medicinal markets were small-scaled and were not paid enough attention. The markets provided convenience for the exchange of local medicinal plants, but not providing a good place for indigenous knowledge. This trend might not be beneficial for maintaining traditional practices and giving traditional knowledge the respect it deserves.

Threats to medicinal plants and conservation practices in the study area
According to informants, nowadays it would take a lot of time and travel long distances to search for some medicinal plants, especially trees and some shrubs. The principal threats of medicinal plants were reported in the study area, including deforestation for agricultural purposes, urbanization, drought, over-harvesting of known medicinal species and firewood collection. Also, informants ranked deforestation for agricultural purposes as the most serious threat to medicinal plants followed by drought, collection of other different factors and firewood. The conservation of medicinal plants was less realized in the study area.
Medicinal plants knowledge secrecy, mode of transfer, gender issue and threats between different social groups within the Maonan area This study highlighted the rich biodiversity of medicinal plants and ethnomedicinal practice in Maonan area to maintain wellbeing and support livelihoods. This study revealed that, most of the knowledge on herbal remedies was handled down to the younger members of the community by elders orally, who were over 40 years old and lesseducated. The Maonan herbalists and healers were male, and only men had the opportunities to study knowledge of traditional medicinal plants in the family. The conservative concept of Maonan healers made a systematic indigenous knowledge of Maonan traditional medicine, which had always been in the hands of a few people. The age structure and knowledge transmission system had the negative influence on the inheritance and development of indigenous knowledge. It dramatically exposed the vulnerability of traditional medicinal knowledge if its transmission was limited by acculturation or inter-ethnic exchange from generation to generation [15,34,35].
Nowadays, the fact is that inheritance of indigenous knowledge is difficulty from the elders to the young generation. Most young people do not believe that studying indigenous knowledge is beneficial for their life because it is less profited compared to working in the urban area. Furthermore, some young people think traditional medicine is anti-science. While male Maonan people work outside, women take responsibility to take care of their families and educate children. If women know how to use medicinal plants, it will be beneficial for training children. According to our interviews, the Maonan women are eager to learn the traditional herbal medicinal knowledge. They may become potential and effective inheritors in the Maonan area, if customary inheriting system allows them.

Conclusions
The paper is an ethnobotanical study on medicinal plants used by Maonan people. We documented 368 species (belonging to 295 genera and 115 families) of medicinal plants used by the Maonans in Huanjiang Maonan Autonomous County, northern Guangxi, southwest China. These plants were used to treat 95 human diseases, such as traumatic injury, bone fracture, health problems associated with the liver disorder, snake bite, and spider poisoning etc. Traditional knowledge about the use, preparation, and application of these medicinal plants is usually passed verbally from generation to generation. The valuable information about medicinal plants could be preserved while recording in the written form. Moreover, the documentation of medicinal plants can serve as a basis for future investigation of new medicinal resources.
Among the medicinal plant species, the whole plants of herbaceous species are harvested from field and constituted the highest proportion of medicinal plants to be utilized. More roots and barks are used than other plant parts, which imply that traditional medical culture in the Maonan area does threaten some species. Although high numbers of medicinal plant species have been reported to be used for human health problems, many wild species are being threatened by various anthropogenic factors while conservation efforts are less practiced in the study area. Deforestation for agricultural purposes is the major threat factor. To save and protect medicinal plants, the external help is necessary, by providing the Maonan people with both seedlings or seeds and cultivation techniques of medicinal plants.
The Maonan men are the only inheritors to transmit traditional medicinal knowledge to the next generations. Unfortunately, the knowledge on herbal remedies is held by elders, who are less educated and above 40 years old. Most young men prefer to look for jobs in urban areas instead of studying the Maonan's medicinal knowledge. It is urgent to find solution of conserving and transmitting the traditional medicinal knowledge in the study area.
Thus, government agencies should encourage the Maonan people to maintain the biodiversity and the ethnomedicinal knowledge by providing the local people with planting materials of the most threatened and preferred medicinal and multipurpose species so that they can grow these plants in their home gardens or farmlands. Public awareness is needed to encourage the local Maonan people to sustainably utilize and manage the medicinal plant resources. Ex situ and in situ conservation measures should be taken to protect the medicinal plants in the study areas from further loss.

Consent
Permissions were provided by all participants in this study, including the local Maonan people. Consent was obtained from the local communities prior to the field investigations. The authors have all copyrights.