Background

Traditional medical systems worldwide have a long history of preventing and treating diseases while supporting community health [1]. As such, traditional medicinal plants have been studied both for conserving ethnomedicinal knowledge [2] and for modern drug discovery [3]. Local communities throughout China have maintained and transmitted rich traditional medicinal systems over centuries, including traditional Chinese medicine, as well as a diverse range of ethnomedicinal practices of the numerous minority sociolinguistic groups of the country [4]. Guizhou Province is one of China’s four major medicinal production areas. It is known as “Western China’s Medicine Center” due to its rich ethnomedicinal resources, including those of the Shui communities [5].

The Shui people, a sociolinguistic group residing in Sandu Shui Autonomous County, are situated in the south of China’s Guizhou Province. The Shui population is around 410,000 [6]. With a long and storied history, the Shui people have amassed a wealth of folk medicinal knowledge, detailing numerous distinctive treatments for local common ailments such as traumatic injuries, bone fractures, and snake bites [7]. This repository of Shui folk medicine has been continually enriched and refined through generations of practical applications. For example, the Shui people's practical need for utilizing herbal medicine to prevent and treat diseases has fostered the development of their distinctive medicinal plants market customs during the Dragon Boat Festival.

According to previous studies, there are more than 300 common medicinal plant species combined in numerous medicinal formulations by the Shui people [8]. Some publications related to Shui medicine include “Shui Nationality’s Medicine” [9], “The Treasury of Knowledge of Medicine of Shui in China” [10], “Summary of Ethnomedicinal Plants in China” [11], and several papers [12,13,14]. The local traditional Shui medicinal knowledge and managing experiences which are practiced, accumulated, and passed down from generation to generation may play a significant role in the sustainable use and development of Sandu plants resources.

In previous publications about Shui medicinal resources [15,16,17,18,19], traditional Shui medicinal plants and ethnomedicinal knowledge have not been systematically reported. Normally, the practice of traditional medicine is handed down through generations, and the old generation who hold the traditional medicinal knowledge must impart it to the next generation of healers before they die. However, nowadays few younger Shui people elect to learn traditional medical practices. Thus, the traditional knowledge regarding herbal medicines in Sandu should be documented immediately to avoid becoming endangered in the near future.

This research focuses on understudied Shui medicinal plants and associated traditional knowledge in Sandu County, with the following three aims: (1) to record the current use of medicinal plants in Sandu County and associated traditional knowledge, including the medicinal plant species used and the types of diseases treated by local healers and any unique aspects of their preparations; (2) to analyze the most important medicinal plant species using relative frequency of citation (RFC); and (3) to provide useful information and data for possible future development and application of ethnomedicine and promote the conservation and preservation of Shui traditional medicinal knowledge.

Methods

Study area

The study area is situated in Sandu Shui Autonomous County, a part of the Qiannan Buyi and Miao Autonomous Prefecture in Guizhou Province, Southwest China (Fig. 1). Located between the Moon and Leigong Mountains, the study area spans 25° 30′–25° 10′ N and 107° 40′–108° 14′ E. Sandu County stretches 56 km from east to west and 78 km from north to south, encompassing a total area of 2380 square kilometers [20]. This region features a low mountainous landform type, with Gengding Mountain in the northwest as its highest point at 1665.5 m above sea level. The lowest point is positioned at the terminus of the Duliujiang River, with an altitude of 303 m, while the average altitude is 675 m. The area’s climate is classified as subtropical humid monsoon, characterized by extended summers and brief winters. The complex terrain, topography, and altitude variations have allowed the county to preserve a wealth of medicinal plant resources, which support the Shui people and their medicinal practices [21]. Preliminary botanical surveys indicate that there are 736 species of angiosperms in this area, and the main timber species include Cunninghamia lanceolata, Pinus massoniana, and Phoebe zhennan [22].

Fig. 1
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Sites for field surveys in Sandu County

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The Shui people

In Sandu County, the Shui people account for 65.93% of the total population, and the remaining consists of Han, Buyi, Miao, and Yao sociolinguistic groups [23, 24]. The historical origins of the Shui ethnic group date back to the period before the Qin and Han dynasties. They were once part of the “Luo Yue” group, which itself belonged to the larger “Bai Yue” collective of ethnic groups inhabiting the ancient Lingnan region. Due to conflicts and wars, they migrated from the Yongjiang River watershed area, traversed Hechi and Nandan, and ultimately settled near the Guizhou and Guangxi border [25]. Over time, they gradually diverged from the “Luo Yue” group and established their own distinct ethnic identity.

The traditional culture of the Shui people still retains many elements of the ancient “Luo Yue” culture. For example, they inhabit elevated wooden structures known as Ganlan-style buildings [26]. These buildings have a dual-purpose design: the lower section serves as an area for livestock and storage of farming tools, while the upper portion is dedicated to human habitation.

The Shui language belongs to the Kam-Shui language grouping within the Sino-Tibetan language family [27, 28]. The Shui people possess their own written language, using the “Shui characters.” However, with just over 400 characters, it is a limited medium for exchanging ideas and is mainly employed for ritualistic purposes, such as worship ceremonies [29]. As a result of their long-standing interactions with the Han Chinese, nearly all Shui individuals are now proficient in both the Shui and Mandarin Chinese languages. Consequently, Mandarin has become the predominant written language in their everyday lives.

In the Sandu Shui Ethnic Autonomous County, generations of Shui people have thrived amidst the high mountains, dense forests, and warm climate. However, due to historical transportation challenges, modern medical resources are often scarce [10]. Through long-term struggles with illnesses, the Shui people have gained extensive experience in using local herbs, which they call “hama,” to prevent and treat various diseases. Within the Shui community, it is common for individuals to be familiar with several medicinal plants, leading to the accumulation of numerous medicinal prescriptions for disease prevention and treatment.

Field surveys

Ten field surveys were carried out from July 2015 to August 2022 (Fig. 2), which lasted for up to 3 months in total, using participatory rural appraisal (PRA) and semistructured interviews, participatory observations, and focal group discussions in the investigation sites [30,31,32,33]. The species, habitats, and varied uses of Shui medicinal plants were collected and documented. The field surveys were carried out in six townships, including Jiuqian, Pu’an, Zhouqin, Dujiang, Dahe, and Zhonghe. The field sites were identified after researchers observed and talked with suppliers in the open markets where medicinal plants were sold.

Fig. 2
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Field surveys conducted from 2015 to 2022

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In the Shui region, most individuals have some familiarity with herbal medicine. However, only a select few individuals are recognized as dedicated Shui healers who exclusively practice this profession. The identified Shui healers were interviewed as key informants for this study. These key informants are renowned local healers with rich medical experience and effective treatment outcomes, serving as vital custodians and contributors to indigenous medicinal knowledge. In addition, other members of the Shui community, who possess only basic knowledge of herbal medicine and do not derive their livelihood from it, were regarded as additional informants. They contributed extensive ethnobotanical data to enrich the information gathered during this investigation.

A total of 15 Shui healers were interviewed as key informants, including 2 females and 13 males. Each of the Shui healers has practiced traditional medicine for more than 25 years. They have had rich medicinal experiences and positive clinical outcomes and are recognized in their communities as important custodians and practitioners in the knowledge of traditional medicine. Interviews with key informants included discussions regarding diseases, compatibility of medicinal materials, processing and treatment methods, taboos, and means of a succession of information. In this study, local Shui healers were followed during their collection of herbal medicines in the fields and recorded the names, medical uses, and parts of the medicinal plants used.

Snowball sampling was used to identify 132 other informants, 66 males and 66 females. The methods of semistructured interviews and guided field walks and focal group discussions were adopted to collect information. The questions included the name, gender, nationality, age, family address, contact information, and other information of the informants, as well as whether they knew and used medicinal plants and the diseases that can be treated effectively.

Fresh and dried plant materials identified during interviews were collected as voucher specimens and deposited in the herbarium at the Minzu University of China in Beijing, China, for future reference. The botanical identities of voucher specimens were confirmed by the authors and other botanists at the Minzu University of China. Plant names were cross-checked with Flora of China (http://flora.huh.harvard.edu/china/) and digital resources from the internet, including http://www.tropicos.org/ and http://www.worldfloraonline.org.

Data analysis

The data were cleaned and inputted into Microsoft Office Excel for statistical analysis. An ANOVA was used to compare the number of medicinal plants recognized by herbal doctors between age-groups and townships [34]. The relative frequency of citation (RFC) was used to evaluate the most common plant species used by local healers to treat various diseases, using the following formula:

$${\text{RFC}} = {\text{FC}}/{\text{N}}$$

where FC is the number of prescriptions mentioning the use of a plant species and N is the total number of prescriptions in this survey [35].

Results and discussion

Key and other informants

Information on a total of 15 local healers was collected through this study, which encompassed six townships. Healers started treating patients by setting up stalls at village fairs, inviting patients to their homes, and providing door-to-door medicinal services [36]. At the township level, Jiuqian township has five identified local healers, followed by Pu’an (3), Zhouqin (2), Dujiang (2), Dahe (2), and only one local healer in Zhonghe (Table 1). These local healers have little or no formal training or education. Their medicinal knowledge is mainly acquired through family inheritance, other healers, or self-study. The specialized Shui healers conduct their treatments in private clinics or township hospitals.

Table 1 Profiles of local Shui healers
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Like other ethnic minorities [37,38,39], Shui communities also face challenges brought by Western medicine to preserve traditional medicine. This is because of modernization and urbanization that have resulted in fewer young people wanting to learn and practice traditional medicine. Low salary is also a fundamental issue that deters younger generations from learning traditional ethnomedicinal knowledge. As a result, the healer demographics skew older, an average age of 54, with only two healers under 40 years old. Healers were grouped by age, and a significant difference in the number of plants recognized by herbal doctors in the three age-groups (F = 54.870, p = 0.002, ANOVA) was identified (Table 2). The results show that older Shui healers have accumulated a rich experience in medicinal plant collection, identification, and treatments. However, ANOVA of the relationships among the number of medicinal plant species recognized in each township, found there was no difference in this study. This suggests that the traditional healers from different townships have a similar knowledge base of medicinal plants, and patients would likely get comparable therapy no matter in what township they sought traditional treatment (F = 0.341, p = 0.566, ANOVA) (Table 3).

Table 2 ANOVA of medicinal plants
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Table 3 ANOVA of number of medicinal plants in townships
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As for the gender structure of the healers, the Shui traditional healers included 13 male and 2 female healers. Most Shui traditional healers pass on their medical skills and knowledge to their sons, and in some cases, their nephews. This male progenitor transmission of traditional knowledge is a common form of inheritance throughout southwest China, such as Miao [40], Yao [41], and Dong [42]. However, this male progenitor system limits the pool of potential healers to only men directly related to the practitioner, and not others in the community, including women or unrelated individuals with an interest in health. Shui men traditionally collect plants, often in remote mountainous areas, and therefore learn more about the diverse medicinal flora of the region, whereas women are more likely to remain closer to home to attend domestic duties. This cultural norm further reinforces the male progenitor custom of healer selection.

Thus, to break this male progenitor system of medical knowledge inheritance, the Shui community is encouraged to collaborate with medical colleges and universities in Guizhou to establish a department of Shui ethnic medicine. This will enable a more diverse demographic of Shui people to receive systematic education and training.

As shown in Table 2, the F statistic is 54.870, and the sig value is 0.002 < 0.01, so there is a significant difference in the number of medicinal plants recognized by healers in the three age-groups.

As shown in Table 3, the degree of freedom is 1, the F value is 0.341, and the sig value is 0.566 > 0.01, so there is no significant difference in the number of medicinal plants recognized in each township.

A total of 132 informants from different demographic groups were interviewed on the therapeutic properties of medicinal plants throughout the six townships under study. As indicated in Table 4, informants were equally divided between females and males. They constituted five age-groups falling in the range of 18–92 years, with the majority being 20–79 years. Nine young people under the age of 20 were reluctant to use herbs, and only two thought herb use was “great,” 21 people between the ages of 20 and 39 were reluctant to use herbs, and six thought herb use was “great,” while more people in their 40 s and older think of using herbal medicine first when they get sick. Moreover, people over 60 are the most satisfied with the efficacy of herbal medicine.

Table 4 Informant demographic data and ethnobotanical data
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The results presented in Table 4 suggest that the demographic variables of informants influence the traditional medicinal plant knowledge of use and efficacy. Data on age-groups clearly show that older people rely more on medicinal plants. Many older people have gained in-depth knowledge of traditional medicine not only from their ancestors, but from their own observations over many years of utilization. Nevertheless, the lack of knowledge among younger generations may be due to changing lifestyles and waning interest in traditional medicine. These changes indicate a high risk of losing such important cultural heritage, and ways to prevent this loss are urgently needed.

Diversity of medicinal plants within the study area

A total of 505 species in 405 genera and 156 families of medicinal plants were documented in the Shui communities (Table 5). Among these 505 species, 130 species were identified for the first time as having medicinal usage, which is indicated by an asterisk in Table 5. The results also provided information on each species, including scientific name, family, Chinese name, local name, distribution, part used, use and value, preparation method, and voucher specimen number (Table 5). Compared with ethnomedicinal documentation in other communities, such as Yao people in Gongcheng County [41], Li people in Wanning [43], Bulang people in Menghai County [44], Tujia and Miao people in Jianshi County [45], Dong people in Tongdao [46] and Yi people in Shilin [47], the Shui medicinal species are especially diverse (Fig. 3). Many of the Shui medicinal plants have the typical characteristics of subtropical species. For example, herbs are mostly annual, and shrubs have strong adaptability and fast growth.

Table 5 Inventory of 505 medicinal plants used by Shui people in Sandu County
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Fig. 3
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Comparison of species number of medicinal plants used in Sandu and other counties in China

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The botanical families with the most medicinal plant species documented in this study are listed in Fig. 4. Fabaceae (27 species) and Asteraceae (24) families occupy the largest proportion of medicinal plants at this study site and are consistent with the wet monsoon climate. This is conducive to the survival of plants with more substantial regenerative and asexual reproduction [48]. Additional popular medicinal plant families include Rosaceae (22), Polygonaceae (13), Lamiaceae (12), Caprifoliaceae (11), Orchidaceae (10), Apiaceae (9), Moraceae (9), Amaranthaceae (8), Rubiaceae (8), Araliaceae (8), Pteridaceae (8), Asparagaceae (7), Ranunculaceae (7), Euphorbiaceae (7), Rutaceae (7), Primulaceae (7), and Campanulaceae (7). Similar results have been shown in Qiandongnan Miao and Dong Autonomous Prefecture, where many medicinal species belong to these families [40]. Although these 19 families accounted for 12.2% of the total number of families used by Shui healers, the number of species included accounted for 42.8% of the total number of medicinal species used, and of the remaining families, each contained only a few species.

Fig. 4
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Nineteen prevalent botanical families with most species numbers used in Shui traditional medicine

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Generally, the medicinal plant resources of the Shui ethnic group in Sandu County have three distinct characteristics:

  1. (1)

    Rich diversity: The findings highlight that the diverse natural environment of Sandu Shui Autonomous County provides local inhabitants with abundant natural resources. These medicinal plants not only help with disease prevention and treatment, but they provide a source of economic livelihood for locals. The rich biodiversity of this region can be credited to the forest protection and environmental traditions that the Shui people have developed and passed down through generations. While preserving forests and ecological environments, the Shui have fostered a symbiotic and mutually supportive relationship. For example, the Shui people frequently designate their revered mountains near their villages as “Dragon Mountains,” believing these mountains to be the foundation of their communities. The prosperity of the village is believed to be significantly impacted by the state of the Dragon Mountain, necessitating special protection measures, such as the prohibition of plant poaching and deforestation. Numerous forest protection and appreciation practices are also integrated into the Shui people's significant life-cycle ceremonies. When a baby boy is born in a Shui family, his father is obliged to plant a tree for the newborn and carefully tend to it, thereby symbolizing the child's growth and development. After a person passes away, Liquidambar formosana saplings are planted in their burial ground, and they are considered “divine trees.” Consequently, these Liquidambar formosana trees can thrive and form small “natural reserves” within the burial grounds. Even if these trees die or branches fall, their use for timber is strictly forbidden. The Shui people's proactive forest protection customs have effectively conserved local forest resources, paving the way for sustainable development in the region.

  2. (2)

    Widespread distribution and abundance: The villages where the Shui people reside are mostly located near mountains and water systems, such as Jiujian, Dahai, and Pu’an, helping to access more easily medicinal plants in the region. According to Shui healers, in the past, farmers from the Jiujian Township could obtain several thousand pounds of Eucommia ulmoides bark each time they collected in the mountains (unpublished results). After a thorough investigation, we observed the most commonly distributed medicinal plants included Lonicera japonica, Ligustrum japonicum, and Houttuynia cordata. Furthermore, each year during the Dragon Boat Festival, the Sandu county seat and its townships maintain a tradition of organizing a medicinal market, where vendors line both sides of the streets, creating a lively and bustling event. The Shui Dragon Boat Festival herbal market has played a significant role in the flourishing of the Chinese herbal medicine market in Sandu Shui Autonomous County. Besides the general public engaging in the buying and selling of herbal medicine, the county’s supply and marketing cooperatives, medical departments, and local produce departments also set up stalls at major intersections to purchase medicinal plants, such as Platycodon grandiflorus, Asparagus cochinchinensis, Ophiopogon japonicus, and Uncaria rhynchophylla. Consequently, a substantial volume of herbal medicine is sold in Sandu annually, establishing it as one of the primary export products of the Sandu Shui Autonomous County. The herbal medicine industry in Sandu shows great potential for further growth and development.

  3. (3)

    Extensive cultivation: In order to make them more easily accessible for personal use, common medicinal plants, such as Celosia cristata, Isodon amethystoides, and Asarum insigne, have been cultivated around houses and on farmland for immediate use. In addition, some Shui people also grow edible wild plants with medicinal properties, like Pteridium aquilinum, Houttuynia cordata, and Capsella bursa-pastoris. The cultivation of these plants does not require time-consuming management or pesticide application, allowing them to retain their authentic flavor. This practice can be viewed as a transition from humans wildcrafting plants in their natural habitat to engaging in cultivation. Additionally, there is also commercial production through cultivation. At present, as farmers and the local government recognize the medicinal and economic value of Shui medicinal plants, Sandu County has initiated large-scale cultivation of medicinal plants such as Eucommia ulmoides, Gastrodia elata, and Mahonia fortunei. This approach has transformed medicinal plant resources into an economic powerhouse for the region, ensuring a steady supply of medicinal materials for businesses and providing an excellent income-generating opportunity for the local community.

Traditional uses and preparation of medicinal plants

The efficacy of medicinal plants is closely related to the plant part used since different parts of the same plant may have different uses and effectiveness [49]. The Shui informants at the study sites used multiple parts of medicinal plants, including the root, whole plant, leaf, stem, bark, fruit, seed, flower, and tuber. Among them, the whole plants were the most popularly used group in terms of species number (221 species), accounting for 25.64% of the total species, followed by roots (21.69%), leaves (12.53%), stems (11.02%), fruits (7.42%), barks (5.45%), seeds (4.52%), flowers (4.18%), tubers (1.39%), and others, including bulbs, vine, and rhizome (6.15%) (Fig. 5).

Fig. 5
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Plant parts used in Shui medicine

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Using the whole plants as medicine is common practice in many ethnic medicines, and traditional doctors believe that this method can enhance the efficacy of the medicine [50, 51]. Although this collection method can cause damage to the local medicinal plant resources and harm biodiversity conservation, it is worth noting that some villagers have taken to cultivating commonly used medicinal plants in their home gardens as an alternative. Furthermore, the county government has taken steps in recent years to initiate reforestation efforts and has implemented administrative measures to safeguard medicinal plant resources [52]. As a result, the issue of destructive collection and excavation has begun to be somewhat alleviated.

In all, 374 traditional medicine prescriptions were collected through interviews with local healers and included nine types of treatments: decoction (278); external application (34); medicinal liquor (36); oral soup (128), and exterior washing (28). The Shui people use fresh medicinal plants frequently, while dry plants are seldom used. This is because the Shui believe the active ingredients of fresh plants are still intact so that this method can optimize effectiveness. However, our investigations found that most plants traded at the market were dried. Local herbal medicine vendors explained that these dried medicinal materials were more convenient for storage. In addition, dried plant materials also were considered to have improved taste and odor, so they are more palatable.

Medicinal liquor, for the prevention and treatment of diseases, is one of the oldest traditional dosage forms in the history of Chinese medicine. These liquors have been widely used in both folk and medicinal industries from ancient times to the present day [53,54,55]. Shui people prepare alcoholic beverages, known in Chinese as jiuqian-jiu, which are made from rice and special starter made of wild plants known as jiuqu [56, 57]. This dosage form has antiseptic and antitoxic properties, which can delay hydrolysis and enhance the stability of many medicines [58]. There are 36 medicinal plant species used for both medicine and Jiuqian liquor starters (Table 6). For example, Lygodium japonicum is used to treat urinary tract infections, hepatitis, nephritis edema, and diarrhea, while the Miao people stew it with meat to strengthen their constitution [40]. Melastoma dodecandrum is used traditionally for expelling wind-damp. A few species are used for both food and medicine, such as Imperata cylindrica and Rosa roxburghii.

Table 6 Plants used for both medicine and Jiuqian liquor starters
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Although Shui medicine is based on the principles of male progenitor lineage, women are primarily responsible for brewing Jiuqian-jiu. The Shui believe that medicinal plants should be harvested around the Dragon Boat Festival to achieve the best curative effect. Therefore, on the morning of the Dragon Boat Festival, the experienced elder female team leader from a village leads other women up the mountains to harvest and clean the medicinal herbs. The team leader then turns the collected herbs into medicinal liquor, which is not easy to prepare, usually taking at least 3 months for fermentation. After the medicinal liquor has been cured, the team leader distributes it to each household, and the women mix it with steamed glutinous rice. After further fermentation, the sweet and nutritious Jiuqian-jiu is ready to drink. All villages in the Shui region participate in alcohol brewing. Sweet rice wine cooked with eggs is a vital source of nourishment for women during their postpartum period. In some villages, there is a tradition of sealing a bottle of freshly brewed alcohol upon a baby's birth, only to be unsealed when the child gets married or passes away, thereby serving as a way to honor ancestors and entertain guests. The most renowned liquor is Jiuqian wine, which has earned a reputation as a widely celebrated specialty.

In addition to medicinal liquor, the Shui often use their secret recipes for healing. For example, when a child’s bone is fractured, it can be fixed with a small splint made of Gonocarpus micranthus for 2 days and then wrapped in a poultice prepared with Sargentodoxa cuneata, Schisandra chinensis, and Eucommia ulmoides for 5 days. Finally, the broken limb is washed with a decoction of Sambucus williamsii, Dichondra micrantha, Rhus chinensis, Ficus tikoua, Sargentodoxa cuneata, and Heptapleurum heptaphyllum. This traditional medical practice involves the use of a number of species instead of a single herb, a common practice of Shui healers.

Although there are various forms of traditional medicine used by the Shui people, including soaking the plants in water to treat ailments like colds, coughs, diarrhea, and hemoptysis, or soaking them in alcohol to treat injuries and rheumatism, as well as using water or alcohol for external application to treat snake bites, insect bites, fractures, and cuts, there are not many other formulations, like ointments, pills, or powders. During treatment, patients are typically asked about their symptoms, but there are no standardized measurements or preparation methods. Thus, Shui traditional medicine is still at the early stage of experience-based treatment, awaiting a transition from empirical to theoretical knowledge, and the elevation of experience to theory.

Diseases treated and characteristics of Shui medicine

Shui medicinal plants are used to treat 85 human ailments [59]. The most prevalent ailments treated with documented medicinal plants are rheumatic diseases (78, 15.45%), bone fractures (63, 12.48%), gastrointestinal system diseases (53, 10.50%), heart and circulatory system (47, 9.31%), respiratory diseases (46, 9.11%), inflammation (44, 8.71%), tonic (27, 5.35%), liver diseases (25, 4.95%), insecticide and snake bite (18, 3.56%), urological diseases (15, 2.97%), ophthalmological diseases (8, 1.58%), gynecological problems (6, 1.19%), skin diseases (5, 0.99%), pediatric disease (4, 0.79%), and others (66, 13.07%) (Fig. 6).

Fig. 6
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Major functions of Shui medicinal plants

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Disease incidence is often closely related to the local environment and climate, as well as ethnic activities and lifestyles [41]. According to the survey, Sandu had the largest number of healers who could effectively treat rheumatic disease, and this may be because Sandu is located in the Moon and the Leigong Mountains. This area is mountainous, with dense forests, high temperatures, rainy weather, wind, cold, and damp heat, and these climatic conditions are conducive to developing rheumatism. From the theory of traditional Chinese medicine, those who live in damp areas should expel wind from their body regularly to relieve constipation and improve their sleep quality, thereby improving their health [60]. Thus, due to their unique environment, Shui people have identified many herbs to treat rheumatism.

Moreover, herbs to treat fractures comprise a large proportion of Shui traditional medicines (Fig. 6). Bone fractures are an occupational hazard for local people engaged in agriculture and forestry. For example, a Shui healer may treat bone fractures with poultices prepared from fresh flowers and bark of Albizia julibrissin, Prunella vulgaris, and Gonostegia hirta. Also, a chicken's internal organs are removed and the chicken is filled with freshly macerated Reineckea carnea for external application to a fractured bone. During interviews with a Shui healer in Dahe Township, we learned that this method was used to successfully treat over 20 patients with bone fractures, with highly effective outcomes.

Popularity of medicinal plants and other health-promoting customs

The RFC (relative frequency of citation) was adopted to evaluate important plant species used by local healers to treat various diseases. From the 374 prescriptions investigated, the number of prescriptions mentioning plant species (FC) used ranged from 1 to 15. Calculations showed that 12 medicinal plant species had FC > 10 (Table 7). The RFC values calculated for these 12 medicinal plant species ranged from 0.027 to 0.041. The medicinal plants with higher RFC values included Isodon amethystoides, Asarum insigne, and Acorus tatarinowii.

Table 7 Relative frequency of citation (RFC) of plant species mentioned in prescriptions, from high to low RFC
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The high RFC values in this study highlight the local healers and residents have a strong dependence on these 12 species of medicinal plants (Table 7). The higher the RFC value, the more familiar the local healers are with the species. Furthermore, and of great importance, these species were either highly effective or abundant and easy to obtain locally. Because of their popularity in Shui medicine, all of these plants should be further studied, focusing on their chemistry, pharmacology, and toxicity, as well as evaluation of the efficacy and safety of local medicinal plants.

For example, Isodon amethystoides is widespread throughout Sandu County and is well known among the Shui people for its medicinal properties. Local traditional Shui healers use the whole plant or root to treat the cancer, autoimmune diseases, and other difficult-to-cure diseases. Compared with some Western medicines, Isodon amethystoides has significantly fewer side effects and can improve the body’s immunological function [61]. With the trend of using naturally occurring substances, drugs from plants have become increasingly important alternative medicines worldwide [62, 63]. Isodon amethystoides deserves further study for drug development.

Asarum insigne, a common substitute for Asarum heterotropoides, has significant pharmacological action, strong therapeutic effects, and easily sourced. In Sandu, it is widely used for the treatment of windchill pain, toothache, broken bones, snake bites, acute gastroenteritis, bacillary dysentery, windchill cough, windchill cold, chronic bronchitis, asthma, and chronic gastritis. Recent experiments have shown that the whole plant of Asarum insigne contains various amino acids and inorganic elements, and has anti-aging, blood pressure- and lipid-lowering effects [64]. Some researchers have processed it to make it more palatable, with a slightly floral aroma [65]. It is believed that through the application of state-of-the-art instruments such as high performance liquid chromatography-mass spectrometry, the effective pharmacological active components of Asarum insigne can be elucidated and it has the potential to be developed into an externally applied medicine.

Acorus tatarinowii is also an important Chinese medicinal material, which is used in the clinical treatment of forgetfulness, tinnitus, deafness, rheumatism, and pain [66]. The growth cycle of Acorus tatarinowii is typically 3–4 years, and its regeneration rate is slow after excessive harvesting. Thus, Acorus tatarinowii resources are in short supply because of the destruction of its natural environment, and thus the price of wildcrafted Acorus plants has been increasing in recent years. Wild Acorus tatarinowii resources are mainly found in remote mountains, and harvesting has become more difficult since young Shui men have been abandoning rural villages for better jobs in urban areas (Table 4). Harvesting wild Acorus is mainly left to some older farmers, and this increases the labor cost, resulting in more expensive Acorus tatarinowii, especially compared with other medicinal herbs.

The Shui people have various customs in their daily life that are closely related to their health. For instance, during festivals, they use Paederia foetida to make rice cakes, and they create “Hui Zong Ba” by mixing glutinous rice with burned rice straw ash, which is rich in calcium, potassium, and other essential elements that supplement their health [65]. As a substitute for tea, the Shui people often drink Ligustrum japonicum, which has the beneficial effects of clearing heat and detoxifying the body. Additionally, Pseudognaphalium affine, a popular wild vegetable for Shui people, has the property of relieving coughs and reducing phlegm (Table 5). The Shui people use Strobilanthes cusia to dye their traditional clothing, which has a therapeutic effect that translates from Chinese to English as “clothing therapy” [66].

Paederia foetida, commonly known as “Jishiteng” in Chinese, has leaves that emit a distinct odor resembling chicken feces when crushed. However, this plant is believed to have medicinal properties that nourish yin and strengthen yang, invigorate qi and blood in the Shui community (Table 5). Glutinous rice cultivation has a long history among Shui communities, who have developed many methods of processing it. One of their favorite delicacies is a steamed cake made by mixing Paederia foetida with glutinous rice. To prepare this dish, glutinous rice is soaked in water for 3–4 h, while the freshly picked Paederia foetida leaves are cleaned, chopped and the juice is extracted through a cheesecloth. The extracted juice is then mixed with glutinous rice powder. A pot of water is brought to boil and sugar is added until it dissolves. The water with sugar is then poured into the glutinous rice and Paederia foetida juice mixture, stirring until evenly distributed. A steaming dish is greased and the mixture is poured in, then steamed in layers until fully cooked. The result is a tasty and fragrant Paederia foetida glutinous rice cake that is considered beneficial to health. Adding glutinous rice and sugar not only eliminates the odor of Paederia foetida, but also imparts a pleasant fragrance to the dish.

The Shui people weave their own clothing and traditionally dye it blue using indigo, Strobilanthes cusia. Even today, those living in rural areas continue to favor indigo-dyed clothes. The Shui often engage in outdoor labor, frequently scratching their hands and feet, so wearing indigo clothes may help to prevent wound infections and alleviate skin itching (Table 5).

Conclusion

The Sandu region boasts abundant medicinal plant resources, and the Shui people have a long-standing tradition of utilizing these plants to treat various ailments in their daily lives. In this study, we analyzed the data collected from 15 healers and another 132 informants who used fresh or dried herbal medicinal material of 505 plant species to treat a wide spectrum of illnesses and diseases, which belong to 405 genera from 156 families, with Fabaceae being the highest represented plant family. Most of the Shui medicinal plants are herbaceous, and healers most commonly use the whole plants in their treatments. Of the 85 different diseases treated by these medicinal plants, a significant number were to treat rheumatism and bone fractures, which may correlate with the local living and environmental conditions. The local people commonly used three medicinal plant species: Isodon amethystoides, Asarum insigne, and Acorus tatarinowii. Further studies on their chemistry, biological activity, and toxicity are needed for potentially developing new pharmaceutical products.

Based on field investigations, this study has comprehensively collected, organized, analyzed, evaluated, and summarized the medicinal plant resources and associated traditional knowledge developed and utilized by the Shui people. The results provide strong scientific evidence for the future development, utilization, and protection of Shui medicine. However, it is important to acknowledge that traditional medicinal knowledge and medicinal plants face great threats from rapid urbanization.

For instance, Jiuqian Town had the highest per capita distribution of healers (Pch), only one local healer was in Zhonghe Township. Of the 15 local healers surveyed in this study, only two were younger than 40 years old. Men and older healers with less education possess most of the knowledge regarding herbal remedies. Meanwhile, most younger people prefer to look for jobs in urban areas instead of studying traditional medicinal knowledge in the countryside. Thus, there is an urgent need to implement policies and practices for the conservation of medicinal plants and their associated traditional knowledge. This will ensure that this valuable knowledge is not lost to future generations.