Ethnomedicinal Knowledge of Pwo People in Northern Thailand CURRENT STATUS: POSTED

Background: Northern Thailand is the home of many ethnic groups who possess great knowledge of ethnomedicine, so it is the location with the highest number of ethnobotanical studies in Thailand. However, the Pwo have never been included in. Therefore, this study is the first ethnobotanical study of Pwo people. Methods: In this study, 50 Pwo informants from 8 villages in Omkoi district were interviewed about their ethnomedicinal knowledge. They were asked about the vernacular name(s) and uses of plant species found in their villages and nearby forests. Results : A total of 122 ethnomedicinal species with 930 use-reports were recorded. Leaves were the most preferred plant part and decoction was the most preferred preparation method. Herbs were the most favored life form of ethnomedicinal plants used by Pwo people. Asteraceae, Fabaceae, and Zingiberaceae were the three most dominant plant families, which contributed 22% of the total species. Most plants with high Use value (UV) values were common species which also found and reported in other ethnobotanical studies however, the exception was Garcinia pedunculata Roxb. ex Buch.-Ham. Although only a single individual was found in nearby forests, but it was commonly used by Pwo people in the studied sites. The five ailments with high recorded IAR included: injuries, muscular-skeletal system, pain, respiratory systems, and digestive systems. These ailments were directly related to the life-style of Pwo people. Conclusion : The comparison between the species found in this study and a study of Sgaw Karen in a nearby area showed that their knowledge differed from each other in both species and their uses despite their close proximity. The results emphasize the importance and the need of ethnobotanical studies although in the areas where many studied have been carried out. The more understanding of the traditional knowledge would increase our chance of understanding and identification of medicinal properties of plants. The results would lead to the discovery and development of new pharmaceutical substances to improve human life quality.

one of the keys to prolonging human life [1], and civilization. Until now, medicinal plants still have an important role in daily life, especially for people who live in rural areas which included about half the global population [2]. Moreover, 90% of the population in developing countries still rely on traditional medicinal plants for their primary health [3]. The uses of medicinal plants differ from place to place and ethnicity to ethnicity depending on the plant diversity around them. Southeast Asia is the harbor of biodiversity and cultural diversity which is reflected in the great variety systems of traditional medicine [4]. Ethnobotany of medicinal plants examines the relationship between biological and cultural parts of the environment [5]. Ethnobotanical study of medicinal plants is an important key to bringing local medicinal plant knowledge into the purview of science and conserving them.
However, all these Karen ethnobotanical publications focus only Sgaw Karen, which was the largest group of Karen. There was no earlier Pwo ethnobotanical publication, so this is the first publication of

Materials And Methods Study sites
The ethnobotanical investigation was carried out in eight Pwo villages in Nakian sub-district, Omkoi district, Chiang Mai province (Fig. 1). The elevations of the studied sites ranged between 938-1460 m.a.s.l. (Table 1). All villages were located in valleys surrounded by dry evergreen forest.
However, Kong Po Tai was also close to mixed deciduous forest because this village was located at low elevation. Nakian sub-district was located about 30 km from the center of Omkoi district. U-toom village was the center of the sub-district while other villages were located about 7-25 km away from this village. The villages were connected by a dusty road which sometimes was impassable in the rainy season. Swidden rice agriculture was practiced in all studied villages along with paddy rice farming. In two villages only swidden agriculture was practiced ( Table 1). All Pwo people in this study are animists and Buddhist.  [14]. The life forms of plants were adopted from Thai Plant Names Tem Smitinand [15].

Data analysis
Use value (UV) The UV was used to compare the importance of species used by the informants [16].  Table 2). The most dominant families were Asteraceae (10 species 8.19%), Fabaceae (9 species 7.37%), and Zingiberaceae (8 species 6.55%) (Fig. 2). There was a total of 930 use reports which were categorized into 22 use categories. The digestive system category was the largest group with 39 spp. and 143 reports (Table 3). Other use categories that had more than 100 use records included muscular-skeletal system, respiratory system, and the pain and injuries categories, respectively. Table 3 The number of used reports, species and IAR of each use category which were reported from 50 Pwo

Plant part uses, life forms, and method of preparation
Leaves were the most preferred part for use, followed by rhizomes/roots, and stems (Fig. 3). These parts contributed to more than 50% of total use-reports. Herbs were the most preferred life form, followed by trees. These life forms contributed to more than 50% of total species found in this study (Fig. 4). Decoction was the main method of preparation (Fig. 5) with half of use-reports prepared by this method.

Informant Agreement Ration (IAR)
The highest IAR (= 0.89) was observed in the injuries use category (Table 3). This category had 126 use-reports and 15 species used. The IAR of the digestive system category, which had highest number of use-reports, was 0.73 which was the third followed by the respiratory system category.
Many use categories had IAR = 0 because the number of use-reports was equal to the number of species used. The IAR of the abnormalities category could not be calculated because the number of use-reports was 1 which made the divider in IAR formula equal to 0.

Plant Use Values (UV)
Use values ranged from 0.02 (use-report = 1) to 0.94 (use-report = 47) ( Table 2). The most used The dominant families in this study were in accordance with those in other ethnobotanical studies in northern Thailand [8,11,[20][21][22]. These families, Asteraceae, Fabaceae, and Zingiberaceae, are cosmopolitan families commonly known for their medicinal properties [23]. Moreover, these families were also listed as some of the largest families in Thailand [24].

Use of ethnomedicinal plants: parts; life forms; and preparation
Leaves are gathered more easily than other plant parts [25]. and are also full of secondary metabolites [26]. Moreover, gathering leaves is more sustainable than other parts because it rarely affects the survival or the reproduction of the plants. Leaves are one of the plant organs which contain many active compounds some of which possess valuable medicinal properties for humans [23]. Hypogenous organs, roots and rhizome, were also preferred by Pwo, the same as other ethnic groups [4,22,27]. These hypogenous organs normally possess a high content of secondary metabolites [28]. which could be used to cure many ailments.
Among the Pwo, herbs were the most frequently used life form, in accordance with ethnomedicinal studies for many other ethnic groups in northern Thailand [20][21][22]. This life form was easy to harvest and the preparation methods and extraction of active ingredient also was also easier than for other life forms.
Most ethnomedicinal plant parts were prepared by boiling in hot water (decoction). This is one of the easiest and simplest methods to extracted active ingredients from medicinal plants [29]. This method is commonly practiced among the ethnic groups in northern Thailand [30][31]. and other parts of the world [32][33].

Ethnobotanical indices
Use values (UV) indicate the relative importance of a specific species used by the informants. Plants have high UV when they are extensively used and known by the informants. Many plants that were reported with high UV in this study were common species: most were widespread or commonly cultivated according to a study in the nearby area [34]. Some of them were widespread exotic  [20]. Most of these plants were used to cure common acute symptoms like bleeding wounds, diarrhea, or common illnesses like cough and headache. So it could be said that one of the factors that promoted the uses of plants in Pwo people is their common appearance in the area. This would allow the local people to become familiar with their properties, resulting in high probability of including them as part of the culture [35]. However, it should be noted that there was a species which had high UV but low prevalence and many species which had very low UVs but were also common species in the areas, e.g. Senegalia rugata (Lam.) Britton & Rose; Toddalia asiatica (L.) Lam.; Solanum torvum Sw., etc.
These species were commonly found and used as vegetable in the studied site. It could be said that low UV of these plants did not indicate that they were unimportant but indicated that the local people were unaware of their medicinal properties [23]. That meant the medicinal knowledge of these plants was at risk of disappearing from the community [36].
One of the notable species is Garcinia pedunculata Roxb. ex Buch.-Ham (called 'Ko-kuy-sa' by local people). The fruit of plant used to treat many ailments, for example diabetes, flatulence, lumbago, etc. (Table 1). However, only a single tree was found in the nearby forest of the studied area but its fruits were widely and popularly used by Pwo people. The extensive use of this plant seemed to be limited to the Pwo people.
There were five use categories which reported both high informant agreement ratios (IAR) and high numbers of use-reports. This indicated that a well-defined selection of species is culturally important for treating these illnesses [17]. Normally the IAR also related to the prevalence of these ailments in the studied area. Most of the informants in this study were farmers so many ailments which related to the hard works in their fields showed high IARs. These included the ailments in the injuries, muscularskeletal system, and pain categories. The respiratory systems category also had high IAR and Nur.
Plants are commonly used to cure respiratory disorders in many parts of the world [37]. Most of these plants in this category were used to treat the common cold and other related symptoms like cough which were common disorders in children [38]. Another use category with both high IAR and Nur among Pwo people was digestive system disorders. Digestive diseases are always reported as among the most important disorders among the ethnic groups in Thailand [4,[20][21][22] The cause of the ailments could be drinking water from forest streams without boiling [4]. It should be noted that high IAR can also help in discovering potentially effective medicinal plants [17].

Comparison of ethnomedicinal plants
Among the 122 species found in this study there were 10 species (8.2%) whose uses were reported in Thailand for the first time. Although the number was not large, but it should be noted that more than 2,000 species were reported in Phumthum et al. (2018) [19] and the accumulation curve indicated that it represents a nearly complete set of used medicinal species in Thailand [19]. This shown that there is still a gap in our knowledge of plant used by local people. Especially, from the ethnic groups which were never been ethnobotanical studied before. Even though they lived in the same area other groups which have been studied for their ethnobotany before. It should be noted that only the plant names, but not use-reports, were compared.
Additionally, there was a significant relation between the UV of plants used by Pwo people and those reported in Phumthum et al. (2018) [19] (r = 0.53, p < 0.01, Pearson's correlation test). The reason behind this could be that most of ethnomedicinal species with high UV were common species which could be found throughout Thailand, so users have more chance to encounter the same common plants which normally tended to have high UVs according to their frequency of appearance [39]. The number of ethnomedicinal plant species found in each family*.

Figure 3
The percentage of each plant parts which were used by 50 Pwo informants, from 8 villages in Na Kian sub-district, Omkoi district, Chiang Mai provinces, Thailand.

Figure 4
The percentage of each plant life from which were used by 50 Pwo informants, from 8 villages in Na Kian sub-district, Omkoi district, Chiang Mai provinces, Thailand.