Dulongjiang Township is located in the northwest of Yunnan Province, China (27°40′ to 28°50′ N, 97°45′ to 98°30″ E), with a total area of 1,994 km². From the upper reaches to the lower reaches of the Dulongjiang River are Dizhengdang Village, Longyuan Village, Xianjiudang Village, Kongdang Village, Bapo Village and Maku Village (Figure 1). Dulongjiang Township is the only settlement of Dulong people in China, with special alpine and gorge landforms, diverse climates, closed traffic conditions, rich biological resources, self-sufficient social economy and unique national culture. Dulongjiang Township is also one of the most biodiverse areas in China, with more than 2,000 species of seed plants in the area. Among them, there are 940 species of economic plants, and there are more than 500 species of plants with medicinal value, such as Paris polyphylla var. yunnanensis, Coptis teeta, Houpoea rostrata, Gastrodia elata, Polygonatum cirrhifolium, Tuber melanosporum, and Cordyceps sinensis.

Dulong, a cross-boundary ethnic group in China, with a total population of 6,930 people, mainly live in Dulongjiang area. It is a township in Gongshan Dulong and Nu Autonomous County, Nujiang Lisu Autonomous Prefecture, Yunnan Province (Li, 1994). The area is known as the “the last secret place in southwest China” (Li et al., 2011). For a long time, the high and majestic Gaoligongshan has blocked the Dulong from interacting with the outside world (Li, 1994). In the process of long-term mutual adaptation with the living environment, they rely on plants to serve their survival needs and maintain life (Geng et al., 2017). For example, there is the collection of wild edible plants, medicinal plants, traditional beekeeping, cultivation of Caryota obtusa, and fuelwood collection (Zhou et al., 2011; Li, 2012; Cheng et al., 2020a, 2022).

The field survey was conducted four times from 2019 to 2020, and the total survey lasted for about 3 months. The survey sites included six villages. Field investigations include semi-structured interviews and participatory observation. A total of 155 informants in the Dulongjiang region were interviewed. Informed consent was obtained verbally from all participants prior to the study (International Society of Ethnobiology, 2006).

During the field investigations, the informants were invited to list all medicinal plants that are still in use or have been used. The interview consisted of two parts: the first part was about the basic information of the informant (ethnic group, gender, age, education, occupation), and the other part included questions related to the detailed information of all medicinal plants, including the locality of the reported medicinal plants, names, use parts, processing methods, application methods, and medicinal effects. The data was recorded and quantitatively analyzed using different quantitative indices.

The nomenclature of all vascular plants follows the Plants of the World Online (https://powo.science.kew.org/) and the voucher specimens were deposited at the herbarium of the ethnobotany laboratory of the College of Life and Environmental Sciences, Minzu University of China in Beijing.

The ethnobotanical data were recorded and analyzed using Microsoft Office Excel 2016, and Origin 2018 was used for drawing graphs and images. The categories suggested for diseases were classified according to International Classification of Primary Care (ICPC) (https://www.who.int/classifications/icd/en/), system for intercultural comparisons, with minor modifications (Staub et al., 2015).

Relative Frequency of Citation: RFC = FC N

The index shows the local importance of medicinal species by frequency of citation (FC) (Barkaoui et al., 2017; Al-Fatimi, 2019). The frequency of citation divided by the number of all informants participating in the survey (N). The higher the RFC, the more important the medicinal plant is in the area (Tardío and Pardo-de-Santayana, 2008).

Informant Consensus Factor: FIC = Nur − Nt Nur − 1

FIC analyzes the degree of difference in the types of medicinal plants used by different herbalists to treat a certain type of disease. It can also reflect the importance of certain plants in the treatment of a certain type of disease in a specific cultural group.

In the formula, Nur is the number of using reports in a particular category and Nt is the number of plant species recorded in the category. FIC values range from 0 to 1. Values close to 1 indicate that relatively few taxa are used by a large number of healers, or there is a clear standard for the use of specific plant species in the community. A low value (close to 0) indicates that the informant does not agree with the use of the plant species in the above treatment categories (Trotter and Logan, 1986).

A total of 155 informants from six villages were interviewed, including 101 males (65.2%) and 54 females (34.8%). The informants ranged in age from 14 to 95, and the mean age was 42, with most of them in the groups between 20 and 39 years old (45.8%), and between 40 and 59 (34.8%). All informants are the Dulong, and the formal education level of the interviewees was low. Among them, 19.4% were illiterate, 25.2% with primary education, and 39.4% with middle high school education. The majority of informants interviewed were engaged in farming work (77.4%), followed by salaried temporary work and trading, and a few were students (Table 1).

The medicinal plants used by the Dulong are diverse. The 155 informants reported a total of 105 taxa including 95 vascular plant species, 8 fungi species, and 2 lichen species used by the Dulong for curative purposes. The Dulong use multifarious types of medicinal plants, including ferns, gymnosperms, angiosperms, fungi, and lichens (Figure 2). All above groups belong to plant sensu lato (kingdom Plantae) according to the two-kingdom system. Botanical information (scientific names, vernacular names, families, and specimen numbers) and ethnobotanical information (medicinal parts, medicinal effect, modes of preparations, and administration) of all plants are listed in Supplementary Table S1.

The RFC can reflect the importance of medicinal plants in the community. Coptis teeta (0.15), Acorus calamus (0.12), Ophiocordyceps sinensis (0.11), Tanacetum tatsienense var. tanacetopsis (0.11), and Paris polyphylla var. yunnanensis (0.08) were shown to be the most useful plants as indicated by their relatively high RFC (Figures 2M–R).

With a wide range of pharmacological activities, like anti-tumor, antimicrobial, and anti-inflammatory, C. teeta is one of the famous regional drug source in northwest Yunnan (Huang and Long, 2006, 2007). The main components of C. teeta are alkaloids such as berberine, jateorhizine, and palmatine. Studies have shown that the berberine content of C. teeta is higher than other plants of the same genus (Yang et al., 2011). Due to habitat loss, change of land use type, and over-collection, the population of C. teeta has declined sharply and is now endangered. At present, C. teeta is listed as critically endangered on ICUN Red List. In the past, the collection of C. teeta was one of the main economic of sources of the local ethnic groups like Lisu, Nu, and Dulong (Huang and Long, 2007). In the 1950s, the sale of C. teeta brought in 50% of their total revenue. Studies have shown that these ethnic groups previously used C. teeta sustainably, based on their religion, including worship of C. teeta planted forests, through the “customary law” to regulate the planting and management of C. teeta, and formed an of effective, scientifically significance based system that mixed agriculture, and forestry in a sustainable system (Huang and Long, 2006).

As an important cultural species, Acorus calamus (chang pu in Chinese) is often used on the Dragon Boat Festival (Shu et al., 2018). During the Dragon Boat Festival, people often hang A. calamus and Artemisia argyi (ai in Chinese) together on the front door to protect family members from evil. Different ethnic groups use A. calamus for different purposes, such as cleaning water, repelling mosquitoes and wrapping zongzi (Shu et al., 2018; Lin et al., 2019). The majority of the Dulong will grow A. calamus in their home gardens to get a ready sufficiently of the medicine, and for ornamental and cultural value. Dulong regarded A. calamus as a sacred and symbolic plant because the leaves of the A. calamus look like swords, with a believed supernatural power to exorcise evil spirits. Local people believe that the A. calamus protects them from diseases. They would place necklaces with A. calamus around children’s necks, believing that this would prevent them from getting sick (Cheng et al., 2020b).

Ophiocordyceps sinensis, Tanacetum tatsienense var. tanacetopsis, and Paris polyphylla var. yunnanensis are important medicinal plants and cash income sources often collected and used by the Dulong. It is very easy to see these medicinal plants in local markets. The Dulong collect O. sinensis every year around April or May, and each one sells for about 5–10 RMB. T. tatsienense var. tanacetopsis is a traditional medicine of the Dulong, and its local name is “Mu Qiu”. It can be taken orally by decocting in hot water to treat indigestion and rheumatism. The Dulongjiang area is very rich in wild resources of Paris. There were three Paris species (P. dulongensis, P. forrestii, and P. polyphylla var. yunnanensis) cultivated by the local people. Due to the appropriate growing environment and strong supporting policy, the plantation of P. polyphylla var. yunnanensis has become one of the main income sources of the Dulong in recent years.

Informant consensus factor can analyze the difference of medicinal plant species used by local people in the treatment of a certain type of disease. In a specific cultural group, it can objectively reflect the importance of certain plants in the treatment of a certain type of disease (Miara et al., 2018; Ojha et al., 2020). Fifty kinds of diseases reported by the informant were divided into 12 categories. The FIC values for all disease types ranged from 0.5 to 0.91 (Table 3). The type of disease with highest in FIC was the circulatory system (0.91), followed by the immune system (0.89), nervous system (0.85), digestive system (0.77), injury (0.75), and musculoskeletal system (0.75). The high value of FIC for circulatory, immune, and nervous system diseases may be due to the limited number of reports and information. The Nt and Nur of digestive system (22, 92), injury (22, 86), and musculoskeletal system (21, 81) were all relatively high, indicating that the Dulong had high consistency in the treatment of diseases of the digestive system, injury, and musculoskeletal system.

The conservation status of all recorded plant species was checked using the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, Information System of Chinese Rare and Endangered Plants (http://www.iplant.cn/rep/), Convention on International Trade in Endangered Species of Wild Fauna and Flora (https://cites.org/eng) (IUCN, 2021). There are 32 medicinal plant species used by the Dulong that can be founded in the IUCN list, and six species are in threatened status (Supplementary Table S1). Coptis teeta and Magnolia rostrata were recorded as endangered (EN), and four species (Gastrodia elata, Paris polyphylla var. yunnanensis, Ophiocordyceps sinensis, Tricholoma matsutake) were recorded as vulnerable (VU). Besides, Dendrobium nobile, Bletilla striata, Caryota obtusa, Cibotium barometz and Fagopyrum dibotrys belong to the national key preserved wild plants (NKPWP) in China (http://www.iplant.cn/rep/). In particular, D. nobile is a first-class national key preserved wild plant. In addition, among these protected endangered plants, three species (B. striata, C. barometz, and G. elata) are listed in the appendix of CITES (Table 4). Although these species are under no threat of extinction, they still face trade pressure and are subject to international trade control.

Traditional Medicine of Nujiang Region (TMNR) is a book about medicinal plants used by ethnic minorities in the Nujiang Prefecture (Zhou and Zheng, 2010). The book recorded 189 medicinal plant species used by ethnic minorities (Lisu, Nu, Dulong and Pumi). In this study, 105 traditional medicinal plant species used by Dulong people were recorded. Comparing with the book, 45 overlapped species between the traditional medicine of Dulong people and the traditional medicine of Nujiang Prefecture, accounting for 42.9% of the total number of the traditional medicine of Dulong people. There are 60 medicinal plants that have not been recorded in TMNR.

By comparing the recorded medicinal plants from this study with other research and databases, we found that four species have not been previously recorded as medicinal plants. Elaeocarpus lacunosus and Vaccinium gaultheriifolium are medicinal dietary plants. The fruit of E. lacunosus was used by the Dulong people to treat traumatic injury. Studies have shown that the fruit of E. ganitrus could act as opioid receptor antagonists to reduce the secretion of neurotransmitters such as acetylcholine, norepinephrine, and dopamine, showing good analgesic effects (Katavic et al., 2007; Hong et al., 2019; Prasannan et al., 2020). The Dulong people use the fruit of Vaccinium gaultheriifolium to treat rheumatism. Studies have shown that the fruits of Vaccinium species represent an important natural source of antioxidants, such as polyphenolic compounds (anthocyanins, flavonols, phenolic acids, and proanthocyanidins) and ascorbic acid that attributed to antioxidant properties (Jurikova et al., 2018). Dulong people used Selaginella sinensis to treat heart diseases. Selaginella species are used in traditional medicine for the treatment of various diseases and conditions in Asia (Bailly, 2021). S. plana were also recorded to treat heart diseases (Dwi, 2009). In China, S. tamariscina is documented in Chinese Pharmacopoeia and used as a traditional medicine for promoting blood circulation. The extract of S. tamariscina was found to have distinctive vasorelaxant activity (Kang et al., 2004). The chemical constituents and pharmacological studies of species in the genus Nabalus have not been reported up to now. Further scientific verifications are needed to reveal their pharmacological mechanisms. In the present study, we also reported 19 new therapeutic uses for 17 known medicinal plant species. These new uses compared to those previously reported in other research and databases were described in Table 5.

In long-term production and living practice, the Dulong use the surrounding wild edible plants to provide food and to alleviate food shortages. There is much overlap between medicine and food, and plants can simultaneously be used as food and medicine (Zhang et al., 2015). Many plants in local food cultures are inseparable from traditional therapeutic systems. Based on our previous research on wild edible plants of the Dulong, we found that among the medicinal plants used by the Dulong, 62 species are edible (Supplementary Table S1). Angiopteris esculenta, a fern species endemic to northwest Yunnan, can weigh more than 20 kg per plant. The rhizome of A. esculenta can be crushed and applied externally to treat skin pruritus (Lu et al., 2021; Cheng et al., 2022). In the past, Cardiocrinum giganteum was an important food source plant for the Dulong. The bulb of C. giganteum can be directly processed into starch after washing and can also be used to make wine. The starch of C. giganteum can be used to treat indigestion. Caryota obtusa is a species of high cultural importance in the daily life of the Dulong. C. obtusa has multiple values, including edible, material, medicinal, and ornamental uses. The stem of C. obtusa is rich in starch, which can be processed into sago used to make baba (local cake), and the processed sago can be used for dysentery and dyspepsia. Stem tips and unflowered bracts of young trees can also be used as vegetables. The trunk of C. obtusa is an excellent building material. C. obtusa is a good ornamental plant with a beautiful tree shape and neat leaves. These medicinal dietary plants play an important role in ensuring food and medical safety. In the future, medicinal dietary plants with economic potential can be developed to make them a source of income for residents and promote local economic development.

The Dulong people are considered to be the last hunting group and seasonal foragers in China (Song, 1999; Fortier, 2014; Hitchcock, 2021). Collecting and hunting were important means for the Dulong people to maintain their daily lives in the past (Du and Chen, 2019). In the long process of interaction with the living environment, many medicinal plants and wild edible plants were consumed, and traditional ecological knowledge about them has been accumulated by local people because of the complicated topography, rainy weather, isolated and remote locality, poor transportation and abundant natural resources. Our previous study documented 148 species of wild edible plants used by the Dulong people (Cheng et al., 2022). Further studies were conducted on some wild edible plants (Angiopteris esculenta, Caryota obtusa, and Maianthemum atropurpureum), demonstrating that the local people’s practice of consuming wild edible plants is sustainable (Lu et al., 2021; Xu et al., 2021). In this study, we found that the Dulong people had high consistency in the treatment of diseases of the digestive system, injury, and musculoskeletal system, which may be related to its frequent gathering and hunting activities in the past. The Dulongjiang valley is one of the richest areas of wildlife in China. It is the core area of the Gaoligongshan National Nature Reserve, which is known as the “Animal and Plant Gene Bank”. Hunting has been banned in order to conserve wildlife. Fishing is also prohibited in some seasons.

Medicinal plants and related traditional knowledge are the basis of the healthy and sustainable development of traditional medicine and provide a guarantee for the survival and health of human beings. The investigation of medicinal plants and related traditional knowledge is of great significance for the conservation of biodiversity, sustainable utilization of resources, and breeding of new varieties (Zhang et al., 2018). With the rapid development of the economy, science, and technology, the improvement of people’s living conditions, and the transformation of lifestyle, more and more people begin to pay attention to traditional medicine, especially in the aspects of health preservation and medicated diet. More and more traditional herbal medicine has been demystified by modern approaches, and the scientific nature of their treatment has been widely recognized (Luo et al., 2020). However, traditional medicine still faces many challenges, which may cause some small populations to lose traditional knowledge of medicinal plants. The major threat to medicinal plants is habitat loss and fragmentation caused by land-use conversion, intergenerational discontinuity, mainstream cultural shock, over-harvesting, and orientation of ecological policy (Figure 3).

Traditional medicinal knowledge has potential contributions to drug development and safeguarding people’s health (Pei and Huai, 2007). Traditional medical knowledge is disappearing faster and faster, especially for the medicine of ethnic minorities in remote areas, which is more obvious.

In the future, four aspects of work for traditional medicine should be carried out. 1) The first step is to conduct a more comprehensive investigation, recording and cataloging of the endangered medicinal knowledge of Dulong through ethnobotanical methods; 2) Followed by research with modern ethnobotanical methods to provide guidance, using new technology (such as metabolomics, transcriptomics, or genomics) to explain the folk use of medicines with scientific evidence. Fully revealing the scientific basis of traditional medicine is conducive to traditional knowledge protection and sustainable development; 3) The continuity and conservation of medicinal plants: Establish a comprehensive Dulong ethnobotanical database, input the utilization information of relevant medicinal plant and upload pictures of plants. It is not only conducive to the dissemination and identification of traditional knowledge but also provides information and reference for the long-term preservation and follow-up research of traditional knowledge (Figure 3).

To make sure of the sustainable use of these plants, there are several suggestions as follows: With the support of science and technology, the cultivation of medicinal plants should be promoted instead of the collection of wild medicinal plants. Innovative use of medicinal plants can be proposed for their conservation and sustainable uses, such as the use of parts, collection times and collection methods. Policies can be issued to promote access and benefit-sharing system of the local traditional medical knowledge. More specifically, if the traditional knowledge is utilized, the benefits should be shared. Thus, it is necessary to make the traditional knowledge holders, providers, and users establish a fair and benefit-sharing relationship and safeguard the interests of local people, which can also be conducive to the protection of the traditional medical knowledge.