Ethnobotanical study of traditional medicinal plants used by the local Gamo people in Boreda Abaya District, Gamo Zone, southern Ethiopia

Abstract

Background

Medicinal plants have been used for centuries and are still relied upon by over 80% of the Ethiopian population. The people of Gamo, southern Ethiopia, have a rich cultural and traditional lifestyle with a long history of using plant resources for various uses including traditional herbal medicine. However, their traditional knowledge of traditional medicinal plants in Boreda Abaya District has not been explored Ethnobotanically yet, despite preserving diverse indigenous traditional medicinal plants. Hence, the study aimed to document and analyze traditional medicinal plants and associated traditional knowledge and practices used by local people.

Materials and methods

Quantitative ethnobotanical data were collected via semi-structured interviews, face-to-face conversations, group discussions, and guided field trips between September 2022 and February 2023. In total, 92 informants participated, of which 25 were key informants. Quantitative data indices (informant consensus factor—ICF—and use report—Ur) were computed by MS Excel spreadsheet software. Scientific names of medicinal plants were checked via World Flora Online.

Results

In the present study, we recorded 188 traditional medicinal plant species belonging to 163 genera and 73 plant families. Lamiaceae (16 species), Asteraceae (16 species), Fabaceae (11 species), and Euphorbiaceae (8 species) contributed highest number of species and were found to be predominant family in the area. Leaves and seeds were most frequently used plant parts, and pounding (46%) was the main method to prepare remedies. The sudden sickness disease category scored the highest consensus (ICF: 0.35), followed by blood and circulatory-related disease categories (ICF: 0.33). The highest number of plant taxa (61 species) used to treat dermal disease has a 71-use report score, while fewer plant taxa (21 species) were utilized to treat genitourinary system-related disease category, having 25 use reports. Ocimum lamiifolium (Ur:56) and Moringa stenopetala (Ur:51) are widely used species and received highest use report value.

Conclusion

Gamo people possess extensive traditional knowledge of ethnomedicine. The region's vegetation hosts diverse medicinal species, but deforestation, agriculture, and droughts threaten them. Local conservation practices require scientific support, prioritizing species having higher use reports (Ur), and in-depth investigations of promising species for drug development are essential.

Background

The human search for drugs goes back to ancient times, and awareness of medicinal plant usage results from many years of struggles against diseases and humans learning to pursue drugs from different parts of plants [1]. The human–plant relationship is not limited to food, clothes, and shelter but extends to health protection [2]. Despite the increasing growth and development of the pharmaceutical industry, the world still consumes ethnomedicine to provide medical care for basic ailments [3]. It is widely reported that about 95% of traditional medicines are sourced from plants and their derivatives [4]. In Ethiopia, traditional plant medicine was used long ago to control various diseases afflicting human and livestock health. Most traditional knowledge is transferred orally, and practitioners are crucial in transferring traditional medicinal knowledge [5]. Some of the traditional practices implemented in Ethiopia include "bone setters" (Wogesha in Amharic), "birth attendants" (Yelimed awalajoch), "tooth extractors," "herbalists," and other spiritual healers such as "Debtera," "Wuqabe," "Kalicha," and "Rukia" (spirit treatments) and major plant-based traditional knowledge has been transferred over generation orally [6, 7].

Traditional medicine has been a significant part of Ethiopia's healthcare system since ancient times [8]. More than 80% of the population relies on traditional medicine for their healthcare needs [9]. These can be attributed to the fact that it is culturally accepted, affordable, cost-effective, and accessible. Additionally, limited access to modern healthcare services in many parts of the country means that rural communities rely on traditional medicine for their primary healthcare [10]. Despite the significant role played by medicinal plants in supporting national primary healthcare, there have been fewer attempts to document and validate the associated knowledge [9]. The existence of interacted culture, ethnolinguistic communities, and geographical diversity blesses the country with the accumulated wisdom of traditional medicines (TMs) which is not well explored, studied, and developed [9]. A limited number (about 1000) of identified medicinal plant species are reported in the Ethiopian Flora; however, many others have not yet been explored and identified [11].

The southern and southwestern parts of the country were enriched with a greater concentration of medicinal plants following the concentration of biological and cultural diversity [12]. However, this rich medicinal plant knowledge is seriously threatened due to deforestation, environmental degradation, and increased population. These serious factors threatened the country's forest, which serves as a source of medicinal plants, causing a loss of indigenous knowledge [13].

Gamo people have a close connection with plants and a traditional lifestyle in the countryside [14]. The vegetation in the region, including 272 sacred groves, contains plenty of medicinal plants [15]. Although different ethnobotanical documentation about several ethnic groups has been published during the past decades in Ethiopia, few ethnobotanical studies have been conducted in Gamo Zone and none in the Boreda Abaya area. It is therefore important to conduct survey to document the medicinal plants and associated indigenous knowledge in Boreda Abaya District. In addition, there is a limitation of infrastructure in the area, including health facilities and schools as compared to other parts of the country; in contrast, the area is rich in diverse and relatively intact traditional cultures and has better forest cover. It is, therefore, crucial to document traditional medicinal plants for local healthcare, and exploring unreached areas can help to update and enrich the flora diversity of the region. Therefore, this study aimed to (i) collect, identify, and document medicinal plants and associated indigenous knowledge of the local people used to treat various human and livestock ailments in the study area, (ii) identify and document candidate medicinal plants used in the study area, and (iii) identify major threatening factor of medicinal plants and recommending feasible conservation methods in the area. The study provides basic information on Ethnomedicine and traditional knowledge of local people in the area, which is useful for primary health care promotion and update of regional flora.

Materials and methods

Description of study site

Boreda Abaya is located at 20° 20′ 0′′ N and 37° 15′ 0′′ E in Gamo Zone of southern Ethiopia. It is one of the largest districts in the area but recently disintegrated into two districts, namely Boreda and Mirab Abaya (Fig. 1). It is about 460 km to the southern direction from Addis Ababa (capital city). Gamo people are the dominant indigenous peoples in the area (83.74%), followed by Welayta (10.06%) and Amhara (2.6%), and their language is Gamogna, which belongs to the Omotic language, and majorly follow Christianity religion. They are part of many Omotic groups living in Ethiopia's current southern regional state [16, 17].

Fig. 1

Map of study site

Mixed agriculture and weaving are widely practiced among Gamo people. The people cultivate a variety of crops such as teff, maize, sorghum, coffee, yam, cassava, mango, banana enset, sweet potato, and taro [18]. Fruit trees such as bananas, papaya, mango, and avocado are widely cultivated [19]. Spices like turmeric, ginger and cardamom are also produced. For instance, Artemisia absinthium, locally called “Arita”, a known medicinal plant in the area is produced on a large area of land for income source. People rear cattle, sheep, goats, and poultry. Skin-related diseases, malaria, intestinal parasitic infections, respiratory tract infections, and typhoid fever are the major public health problems in the district (unpublished data, Boreda Woreda Health Office, 2023). Blackleg, chicken pox, “Gend,”/ shivering are some of the domestic animal diseases (unpublished data, Boreda Woreda Agriculture Office, 2023).

Topographically, Boreda Abaya has three agroecological zones, namely lowland, midland, and highlands, with an elevation between 1100 and 2942 m.a.s.l. It has an estimated area of 1,322.04 square kilometers. The districts' total demography is estimated at 276,249; 139,249 men and 137,000 are females, and only about 4% to 7.78% are urban dwellers. It receives an annual rainfall range between 900 and 2600 mm in bimodal regimes; the first round of rain occurs between March and May, and the second round occurs from June to August. The temperature ranges between 22.5 and 27 °C.

Data collection

Ethnobotanical data were collected between September 2022 and February 2023 through pre-planned semi-structured questionnaires, face-to-face interviews, field walks, and group discussions [20,21,22]. With local elders,' herbalists,’ and agricultural DA consultation, six vegetation potential kebeles (minor administrative level in Ethiopia), Kodomoko, Dega zonga, Zefene, Hamesa, Uomo lante, and Wanke-Wajifo were targeted in our field trips and other places randomly selected based on availability of herbal medicine and practitioners (Table 1). In total, 92 residents participated, and 25 of them were key informants. Key informants were interviewed for an extended time to gain detailed knowledge about medicinal plants, and they were supposed to be knowledgeable practitioners [23]. The remaining 52 respondents were chosen randomly by giving a number to each household in order, and one person from each house was interviewed. The data are primarily sourced from key informants since they are expected to be knowledgeable about herbal medicine. During the field trip, we collected information on ethnobotanical data such as local plant names, plant parts used, habitat, preparation methods, modes of application, routes of administration, treated disease type, multipurpose uses, threatening factors, and availability of medicinal plants.

Table 1 Specifically visited site within Boreda Abaya District of Gamo Zone, southern Ethiopia

Ethical considerations

Supportive letters were written from Shashemene Botanical Garden to concerned bodies, such as the District Agriculture Office, District administrators, and Kebele administrators, before field trips. We ensured that ethical principles were considered; all herbalists were informed that the purpose of the study was for academic purposes and ethical approval was obtained to ensure confidentiality before conducting interviews. During our research, we maintained the confidentiality of local communities' secrets, knowledge, and taboos while recording notes [22].

Plant specimen collection/vouchers

During field trips, we collected plant specimens of medicinal plants with the help of herbalists and development agent experts. Two to three specimens from each species were collected to ensure the collection's authenticity. We attached collecting labels with the collection number and collector names. The specimens were correctly placed in the middle of two or three pieces of locally made blotting paper, with some facing up and some facing down to capture both sides. Finally, they are held together and tightened by a specimen presser and holder. The vouchers were dried under sunlight by placing holder side face toward the sun and aerated to check insect strains.

The collected specimens were identified and verified at the herbarium of the Ethiopian Biodiversity Institute/Shashemene Botanical Garden, using taxonomic keys and descriptions from the relevant volumes of the Flora Book of Ethiopia and Eritrea [24,25,26]. A visual comparison of the specimen with authenticated specimens was conducted to authenticate the identification. The voucher is preserved in the Shashemene Botanical Garden plant herbarium (SBGH). The scientific names, families, and their authors' names of recorded plants were checked in the International Code of Nomenclature for algae, fungi, and plants, World Flora online: https://wfoplantlist.org/, https://powo.science.kew.org/ and Natural database of Africa (NDA). In our field trip, we used a field guidebook of useful trees and shrubs for Ethiopia [24].

Data analysis

Collected data were analyzed by following the techniques in Martin [27] and Höft et al. [28]. Ethnobotanical data were summarized and analyzed on Microsoft Office Excel using descriptive statistical methods. Quantitative data analysis was conducted using the informant consensus factor (ICF) and use reports (number of citations or mentions). Fidelity level (FL) for some species is computed for additional information. Accordingly, the informant consensus factor was computed following the formula, ICF = Nur-Nt/Nur-1, where ICF = informant consensus factor, Nur = number of species used for each category, and Nt = the number of species used for all ailments. Its values range from 0 to 1, and when values are close to 1, it indicates a high consensus on plant species used against a disease category, and 0 possesses an opposite significance [29]

The mentioned disease conditions were grouped into nine major disease categories based on their sign and symptoms, pathogenic agents, and human or animal parts they attack. The relative therapeutic capacity of medicinal plants used to treat diseases was determined by fidelity level and computed as FL = (N/n) * 100, where N is the number of informants that claim the use of a species to treat a particular disease and n is the number of informants that use the plant to treat any ailments. A higher FL level indicates high usage of a medical plant for a particular disease, while a low FL level confirms a wide range of medicinal uses but a low frequency for each ailment.

Results and discussion

Demographic features of the respondents

The study took place in Boreda Abaya, where most local people belong to the Gamo ethnic group. Of 92 residents who participated in the field trips, males account for a higher proportion than females (76.1%, mentions 136 species) due to the cultural expectation that women primarily work at home while males work in the field (Table 2). The number of females was 22, covering 23.9% and mentions 52 species. The age group of respondents mostly belonged to the 41–60 years old category (41.3%, mentions 108 species), followed by the 20–40 age group (31.5%, mentions 32 species), and the minor age group was 61–84, covering 27.2% and mentions 48 species. This indicates that while older people cite more medicinal plants, their number is less due to aging.

Table 2 General background of informants and species reported features

Most informants are illiterate (70.7%, mentions 129 species), with some able to read and write (16.3%, mentions 48 species), attend primary school (2.2%, mentions 3 species), secondary school (5.4%, mentions 3 species), or college (5.4%, mentions 5 species). Farmers and healers account for more occupations (76.1%). A few are only employed in traditional medicine (9.8%), some are students (7.6%), and others are government employees (6.5%).

In the study, it was observed that individuals belonging to the category of farmers and herbalists showed a greater tendency to mention medicinal plants (mentions 110 species) as compared to other informants (Table 2). Informants employed on herbal treatments alone mentioned 67 species. Notably, the highest number of medicinal plants shared by a single healer was 36. Conversely, those who were employed (mentions 5 species) and younger (mentions 6 species) tended to mention 1–2 medicinal species, while farmers and older residents cited a wider range of species. However, it is important to note that it was difficult to obtain comprehensive information regarding traditional medicine from young people because of their limited knowledge in this area. Even though older people mentioned more species, they faced obstacles in accessing those species due to aging and the deforestation of nearby forests. The lack of conventional knowledge among young people causes a risk of the disappearance of traditional knowledge of medicinal plants [30, 31].

Taxonomy, floral diversity, and life form of Gamo medicinal plants

In total, 188 medicinal plants belonging to 163 genera and 73 families were recorded in the present study (Table 3). Many of those species were utilized for human diseases (123 species). Fewer species (11 species) were recorded for domestic animal disease treatments, and 54 species were used for human and livestock diseases. These results show that local healers prioritize human diseases and utilize diverse plant species in treatment, resulting in richer traditional knowledge. Furthermore, the large number of recorded species indicates that the vegetation of the study area is a reservoir for diverse medicinal species, supporting their critical importance in plant-based traditional medicine in fulfilling the needs for primary healthcare. Prominent plant families, Lamiaceae (16 species), Asteraceae (16 species), Euphorbiaceae (11 species), and Fabaceae (11 species), contributed a significant number of species and well-represented families in the area (Fig. 2). Species from those families can survive in various ecology and widely distributed to the local environment [15]. Those families host larger species composition in different ethnobotanical surveys conducted elsewhere in the country [32, 33]. They also accounted for a more significant portion of the country's Flora due to widely dispersed, readily available, and more utilized families [31, 34,35,36,37,38]. Species of those families are widely used due to their essential phytochemical compounds, which provide significant health benefits [39]. For example, Ocimum species (Lamiaceae) are rich sources of tannins, phenolic acids, anthocyanins, phytosterols, policosanol, and essential oils, which have potential biological activities such as antimicrobial, antioxidant, anticancer, and anti-inflammatory properties [39].

Table 3 Ethnomedicinal plants used by Gamo people of Boreda Abaya District and their traditional methods of remedy preparation (sorted by family name)

Fig. 2

Distribution of predominant medicinal plant families in the Boreda Abaya District

Ocimum lamiifolium contains flavonoids, tannins, and saponins, and its oil is the primary source of linalool [40, 41]. Furthermore, Artemisia species, part of the Asteraceae family, are widely grown in the region and commonly utilized for cultural and commercial purposes. They contain various beneficial compounds, including disaccharides, polysaccharides, glycosides, saponins, terpenoids, flavonoids, carotenoids, and essential oils. These plants have significant biological importance, serving as antiparasitic, anti-malarial, antihyperlipidemic, antiasthmatic, antiepileptic, antitubercular, antihypertensive, antidiabetic, antiemetic anxiolytic, antidepressant, anticancer, hepatoprotective, gastroprotective, insecticidal, antiviral agents, and even against COVID-19 [42]. An important compound extracted from species of Artemisia, Artemisinin, is used to produce drugs for treating malaria and viral diseases [43, 44]. In-depth explorations, phytochemical isolation, and characterization of species from those prominent families are essential for novel drug discovery [45, 46].

Herbalists in the study area mainly use herbaceous plants, with 71 species, followed by shrubs, trees, climbers, and epiphytes with 59, 35, 21, and 2 species, respectively (as shown in Fig. 3). Herbaceous species are primarily available during the rainy season, while some herbalists collect a few plants in their home gardens. Some species are harvested during the rainy season and kept for use in drier times. For instance, species such as Acmella caulirhiza, Echinops amplexicaulis, Gnaphalium rubriflorum, Gnidia stenophylla, and Pennisetum sphacelatum were harvested during the rainy season and stored for use in the dry season. Thunbergia abyssinica and Impatiens rothii are among endemic species found to have a high distribution in the area. Echinops amplexicaulis was found to be distributed widely and is a vital herbal species in the region. However, moss and liverwort were not encountered in the study, most likely because they grow during the rainy season. Healers confirmed that they could not usually assess those species frequently in the dry season. In Ada’a district, in other parts of the country, most people utilize shrubs for traditional medicine [47]. However, the present findings support herbal extraction of Ethiopian medicinal plants, which has attracted interest of researchers due to their potential sources of active compounds that benefit against several diseases and play a critical role in meeting society's basic medical demands. Hence, they are significant sources of medicine for the local communities [33, 48, 49].

Fig. 3

Habits of recorded medicinal plants

The present study documented higher number of medicinal plants species as compared to other similar studies conducted elsewhere in Ethiopia with a range of ethnic groups. This comparison is important to overview the Ethnolinguistics diversity and availability of medicinal plants. Further it highlights promising therapeutic medicinal plant species used for drug discovery [46]. Among others, a study conducted on medicinal plants used in Loma and Gena Bosa Districts of Dawro Zone, documented about 178 species, southern Ethiopia [50]. Fisseha Mesfin (2009) documented 198 plant species in Wonago Woreda with Gedeo community, Southern Ethiopia [51]. Similarly, Endalew Amenu (2007) documented a total of 188 plant species with indigenous people of Ejaji area, Chelya District, west Shewa in Ethiopia, and the highest informant consensus was recorded for Ocimum urticfoluim in treating febrile illness in the area [52]. Moa Megersa (2010) documented 126 MPs for their medicinal uses in Wayu Tuka Woreda, East wollega Zone of Oromia Region, Ethiopia, found Acmella caulirhiza was the most preferred medicinal plant by local people of the study area to treat tonsillitis [53]. Similarly, the Afar people in Chifra have reported the healing potential of Aloe spp for malaria [54]. In the Wonago area, Artemisia afra mainly used for headache treatment [51]. The Sheko people in southwestern part of the country uses Ocimum lamiifolium and Phytolacca dodecandra, to treat skin and gastrointestinal diseases[51]. Zingiber officinale for tonsillitis, Clerodendrum myricoides for tumor, Hagenia abyssinica for tapeworm, Ricinus communis for rabies, Prunus africana for wound healing around Bale Mountain [25]. The presence of above-mentioned species in present study may indicate the healing potential of those medicinal plants and importance of local vegetation in the present study area for traditional medicine reserves. The present study reports on the wide usage of various new species, such as Acanthus sennii, Gnaphalium rubriflorum, Gnidia stenophylla, Impatiens rothii, Olea welwitschia, Pennisetum sphacelatum, Solanecio gigas and Thunbergia abyssinica. These findings contribute new plant uses to the field of Ethnopharmacology in the country (Table 3).

The relatively high availability of herbaceous medicinal plants in comparison to other plant habits could account for their widespread use in different corners of the country [55, 56]. They adapted to wide environmental ecology and exhibit major plant habits [15]. Acanthus sennii, Echinops kebericho, Ensete ventricosum, Erythrina brucei, Impatiens rothii, Kalanchoe petitiana, Lippia adoensis, Millettia ferruginea, Solanecio gigas, Urtica simensis and Vepris dainellii are some of the widely distributed endemic medicinal plants in the area (Figs. 4, 5 and 6).

Fig. 4

Preparation methods of ethnomedicine

Fig. 5

Ethnomedicines application routes

Fig. 6

Ethnomedicines application modes

Wild forest is the main source of Gamo medicinal plants, accounting for 128 species. Others are collected from home gardens (43 species), farmlands (11 species), and roadside (6 species). This finding coincided with similar study results conducted elsewhere [38, 48, 49, 57,58,59]. Healers keep track of the best locations for different species of plants in the forest. They also help researchers obtain unbiased data from local healers while ensuring that they maintain strict confidentiality about cultural beliefs and practices. This information is valuable in studying medicinal plants [32, 36]. However, conservation efforts to preserve these plants are limited in the area, even though the natural forest is rapidly disappearing due to various factors like deforestation [60]. This is concerning because the loss of forest environments translates to the loss of valuable traditional knowledge about medicinal plants [33]. The local vegetation has ever green riparian and swamp forest, small leaved deciduous woodland in hill mountain of Ganta, and at higher altitudes it is possible to observe patches of Bamboo species [15].

Ethnomedicine preparations and plant part used

Ethnomedicine practitioners of Gamo people use basic techniques and locally available materials, like mortars and pestles, to prepare remedies. A recent study has identified nine major preparation methods, with pounding (104 mentions) and crushing (47 mentions) being the most used. Other methods include cooking (roasting), powdering, grinding, squeezing, boiling, burning, chewing, and chopping, although these were mentioned less frequently. Gamo herbalists use wooden mortars and pestles, known locally as "Mukacha," to easily pound or crush plant parts with common ingredients like honey, coffee, salt, and butter. These additions serve to improve the nutrition and flavor of the remedy for the patient. For instance, a similar practice has been reported in the traditional medicine of the Maonan people in China, where locals add ingredients such as honey, butter, and meat to enhance the nutrition and flavor of the remedies they prepare [61]. Further herbalists merge multiple species to enhance the healing potential of remedies. The present study has identified 12 species of plants that exhibit synergistic effects when used in combination to prepare remedies (Table 3). This discovery is significant as it allows for the development of more effective and targeted treatments for various ailments and health conditions. Among others, Allium sativum, Argemone mexicana, Datura stramonium, Ensete ventricosum, Ocimum lamifolium, Ruta chalepensis, Solanum incanum, Thymus schimperi, Trigonella foenum-graecum, Withania somnifera and Zingiber officinale are frequently mentioned for their synergic therapeutic use. This traditional practice needs to be supported by scientific studies to overview whether the combination has negative or positive effect, but it clearly shows local herbalists merge more species to prepare effective remedies for fast recovery of patients.

As shown in Table 4 below, about 50% of Gamo traditional medicine was mainly prepared from leaves (119 mentions, 93 species), followed by seeds (33 mentions, 26 species). Other plant components like fruits, bark, stem, tuber, latex, whole portion, flower, and bulbs were also used by Gamo healers in their ethnomedicinal preparation. A similar finding was reported by informants of Kafficho and Sheko people in the southwest part of the country, revealing that leaves and seeds were widely used plant parts, showing the ethnolinguistic interaction of different people and effective concentration of bioactive components present [30, 31]. The cultural, traditional interaction might link ethnobotanical knowledge transfer among various people. However, the present finding contradicts the results of a study conducted elsewhere in the Wonago area, where roots were found to be the most used plant component [37].

Gamo practitioners collect various plant components for remedy preparation under different use conditions. Out of 188 species, 145 species were used in fresh form, 21 in dry form, and 22 in both forms. They prefer to prepare remedies in a fresh form as patients come, and most herbaceous species are usually used freshly. However, when a plant is not easily accessible, herbalists prepare it in dry form, believing it retains its therapeutic properties for a longer time. For instance, a Gamo remedy made from Nicotiana tabacum to alleviate asthma, headaches, and coughs is prepared in dry powder form for long-term use (up to a year). Several studies suggested the preference of fresh plant parts by local herbalists [30, 33, 62] which implies that healers regularly collect plant parts [63].

It is a well-established fact that overharvesting has serious consequences for the survival of medicinal plants [64,65,66]. Despite this, the herbalists of Gamo have developed an effective solution by carefully tending to the mother plants during collection due to their traditional cultural law known as "Wagas and Dubusha," which stems from the belief that everything is connected and bound in a delicate balance. It dictates everything from interpersonal relationships to the conservation and preservation of pasture, forest, soil, and water, because in Wagas all are interconnected, if any one aspect is denied or imbalanced then the whole system is understood to be at risk. This reflects a cultural value that emphasizes sustainable usage and environmental harmony and plays a vital role in preserving local biodiversity [14]. Comparatively, using leaves affects the species' lifecycle less than other parts like root and bark. But some species, such as Echinops kebericho, Embelia schimperi, Hagenia abyssinica, Moringa stenopetala, and Withania somnifera, have been targeted for their roots or whole plant parts, resulting in possible extinction of those species in the area. Many medicinal plants are overharvested, which puts them at risk of becoming a threatened species. One such example is Taverniera abyssinica A. Rich, whose slender roots are wrapped in small, coiled bundles and sold as medicine. The species is not encountered in the present study. This species is currently threatened, and less data are available in Ethiopia [11].

Route of administration, application mode, and dosage determination

The current study recorded five primary routes of remedy administration—oral (via mouth), dermal (external), nasal, optical, aerial drop, or injection. Gamo healers prefer to use drenching (10 mentioned), rubbing (36 mentioned), or directly eating plant parts (36 mentioned) to treat illnesses. They carefully consider the patient's condition, sex, age, disease type, and other factors to choose the best route, method of application, and dosage. Gamo healers do not recommend oral use of herbal remedies for children and pregnant women (25 mentioned) due to dosage problems [33]. A few other informants (7 mentions) prefer external treatments for children to minimize risks. Similarly, Sheko people healers suggest that a taenicide prepared from fruits of Embelia schimperi should not be given to children under 15 due to its adverse effect [30], indicating shared traditional practices.

Herbalists employ various methods to accelerate the healing process, and some of these methods involve multiple routes. In Gamo, herbalists adopt certain precautions for patients, such as refraining from food and drink and spending the morning alone without ingesting food, to enhance the efficacy of remedies. For instance, in the treatment of tapeworm disease, the herbalist prepares a remedy from the Hagenia abyssinica species, which the patient takes before breakfast and then fasts for a prolonged period, typically six hours, to expel the worms from the intestine effectively. Similarly, for febrile illness, or locally called Mech, the herbalist fumigates the patient with smoke from the Ocimum lamiifolium and Eucalyptus citriodora species and advises the patient to sleep as soon as possible. The herbalist makes a diagnosis by conducting visual observations of the patient's eye and skin color, tongue and throat regions, and body temperature while also inquiring about the patient's symptoms. This approach is consistent with the findings of a range of ethnobotanical studies carried out elsewhere in different regions of the country [38, 57].

Traditional healers use simple and often unconventional techniques to determine the appropriate dosage for their patients. For instance, in some cultures, healers use finger strips, glasses, coffee cups, or teaspoons to measure the dosage, depending on the age and sex of the patient. However, the lack of a standardized dosage poses a challenge to the safety and efficacy of traditional medicine.

In some communities like the Gamo people of Ethiopia, healers order different amounts of dosage based on the patient's age, sex, and physical condition. They also use various inputs such as milk, coffee, honey, meat, and "Tella" (a local beer) to reduce the side effects of ailments. These practices reflect the cultural diversity and richness of traditional medicine but also underscore the need for standardization. Dosage and safety are shared problems among the traditional practitioners of the country due to the lack of a solid standard for traditional medicine. It is essential to develop a regulatory framework that considers the unique cultural practices and knowledge of traditional healers while ensuring the safety and efficacy of their treatments [32, 51, 67] (Table 4).

Table 4 Plant part used in remedy preparation

Treated disease type and the healing potential of medicinal plants

Gamo healers used medicinal plants to treat around 80 different disease conditions, grouped into nine broad categories, as shown in Table 5. The sudden sickness disease category received the highest ICF value (ICF: 0.35), followed by blood and circulatory-related disease diseases category (ICF: 0.33). While the lowest ICF values were observed for malaria (Ur: 17), rabies (Ur: 1), snake bite (Ur: 3), Gend/shivering (Ur: 3), insect bite (Ur: 1), disease categories (ICF: 0), and gastrointestinal-related disease (ICF: 0.12). Dermal diseases categories received the highest number of use reports (Nur: 76) and plant species used (61). In contrast, genitourinary system diseases categories including STDs had the lowest value of use reports (Nur: 25) and plant taxa (Nt: 21). The ICF result analysis indicates that the Gamo community employs a variety of plant species to cure specific ailments, underscoring the significance of the region's diverse ecosystem. Moreover, the heterogeneity of medicinal plants used by the Gamo people is a testament to their extensive knowledge of traditional medicine and their ability to interact with natural phenomena to identify essential plants.

Table 5 Informant consensus factors (ICF) value of disease categories

As shown in Table 5, some of the specific diseases reported frequently have high-use reports, implying that Gamo herbalists mostly treat them. Among others, skin-related disease is the leading case, having 47 use reports, followed by wound cases, having 29 use reports, headache, 27 use reports, and malaria, having 15 use reports. This might be related to the lifestyle of local communities, which is mainly agricultural farming. Other cases, including breast pain, mastitis, typhoid, bronchitis, insect bites, and epilepsy, have low use reports (1) and are among traditionally treated conditions. The analysis of the results demonstrated the informants' consensus to determine the efficacy of reported species for a disease category, which might pave the way for searching the pharmaceutic potential of these species by identifying active compounds.

The study reported that the plants with the highest number of use reports were Ocimum lamiifolium with 56 reports, Moringa stenopetala with 51 reports, Acmella caulirhiza with 41 reports, and Croton macrostachyus with 40 reports. These could be attributed to their ability to adapt to local environments and their effectiveness in conventional uses. Moreover, Ensete ventricosum, Manihot esculenta and Moringa stenopetala are widely used for food and fodder in the study area. Coffea arabica (with 27 use reports) and Artemisia absinthium (with 14 use reports) were used for commercial and cultural ceremonies. Some species, such as Nicotiana tabacum (with 36 use reports), Hagenia abyssinica (with 35 use reports), Echinops kebericho (with 27 use reports), and Echinops amplexicaulis (with 23 use reports), were used solely for their medicinal values.

The potency of species that have higher usage reports is likely correlated with the presence of secondary active metabolites, which make them effective in inhibiting various oxidations and biological activities. The prevalence of bioactive compounds such as terpenoids, flavonoids, tannins, saponins, steroids, and essential oils containing linalool, 1-octen-3-yl-npropionate, and 3,7,11-trimethyl-(E, E)-2,6,10-dodecatrienal makes Ocimum lamiifolium more effective in treating different diseases [40, 41, 69]. Moringa species possess functional bioactive compounds, including phenolic acids, flavonoids, alkaloids, phytosterols, minerals, and organic acids, which make them highly effective in inhibiting multiple biological activities. These activities include antiproliferation, hepatoprotective, anti-inflammatory, antinociceptive, antiperoxidative, cardioprotective anticancer, anti-ulcer cardiovascular, anti-obesity, antiepileptic, antiasthmatic, antidiabetic, anti-allergic, anthelmintic, wound healing, antimicrobial, immunomodulatory, and antidiarrheal properties [70,71].

Compounds such as alkaloids, tannins, saponins, terpenoids, and steroids, along with 4-hexen-1-ol, (E), bis(2-ethylhexyl) phthalate, [1,1'-biphenyl]-2-acetic acid, epizonarene, cyclopentene, 3-isopropenyl-5,5-dimethyl, and 3-carene, might contribute to the healing potency of Croton macrostachyus [72,73]. A review study on the anti-malarial effects of the species revealed the existence of cyclohexane diepoxides, such as crotepoxide, lupeol, and betulin; cis-clerodane; crotomacrine; 3β-acetoxytetraxer-14-en-28-oic acid; trachylina-19-oic acid; and trachylina-18-oic acid, which contributed to a higher anti-malarial effect [74].

Traditional healers in Gamo use different plant species to cure specific diseases. Informants identified the top ten plant species that have the highest potential to heal, along with their fidelity level (FL) score. The plants with high healing potential include Ocimum lamiifolium, which is effective in treating febrile illness, with an FL score of 1. Withania somnifera is useful for curing the evil eye, locally called Buda, to mean spiritual problem with a score of FL: 1. Hagenia abyssinica, Tamarindus indica, and Acmella caulirhiza are effective in treating tapeworm, wound healing, and febrile illness, respectively, with a score of 1. Echinops. kebericho is helpful for cancer and sudden illness, with a score of FL: 0.93. Schefflera abyssinica is effective for wound healing, with a score of FL: 0.91. Zingiber officinale is useful for tonsillitis, with an FL score of 0.87. Jasminum grandiflorum is effective for earache and cough, with a score of FL: 0.86. Eucalyptus globulus is helpful for febrile illness, with a score of FL: 0.86.

The Gamo healers prefer some species over others when preparing remedies for specific ailments. Six key respondents ranked their preference of potent species for curing certain conditions. This preference could help herbalist to select most effective species over others to prepare effective remedies for better treatments. Furthermore, it also shows the potential species for specific ailments. Jasminum grandiflorum (36 scores), Carissa spinarum (35 scores), and Croton macrostachyus (34 scores) were preferred for treating skin diseases over other plant species, including Withania somnifera (31 scores), Commelina benghalensis (26 scores), Datura stramonium (24 scores), Vernonia amygdalina (15 scores), and Paullinia pinnata (13 scores). While Acmella caulirhiza (76 score) and Coffea arabica (70 score) are preferred for their wide use for their wound-healing capacity over Xanthium strumarium (60 score), Argemone mexicana (59 score), and Leptadenia hastata (53 score). Croton macrostachyus (75 score) is preferred for its effective wound and skin disease healing capacity. The more preferred species have a significant role in treating diseases in the study area, and these might probably open a door for further studies focusing on identifying specific species trial and cytotoxicity tests for their effectiveness against stated ailments.

Educational level, age, and traditional knowledge

Our research has revealed a strong correlation between age and knowledge of ethnobotany. Individuals aged over 40 were found to have a better understanding (Table 2). In addition, males tend to have higher exposure to ethnobotanical knowledge than females due to local cultural practices. Interestingly, illiterate people tend to rely more on medicinal plants, while those who are educated prefer modern drugs. Gamo healers pass their knowledge to their first son verbally. These oral transfers are likely because respondents cannot document due to illiteracy. It is important to note that younger residents require more knowledge about ethnobotany to preserve this valuable traditional knowledge [57].

Major threats and conservation of Gamo medicinal plants

Six major factors threatening Gamo medicinal plants were mentioned by respondents as shown in Table 6. Key respondents were coded as R (respondent) to rank the major threatening factors. Those factors ranked based on their devastating impact on medicinal plants and natural resource as whole. Among others, deforestation, agricultural expansion, and drought were ranked main threatening factors to local biodiversity including medicinal plants. Others such as charcoal use and construction ranked low as the study area is a remote rural area. This is another significance of the present study contributes to environmental protection by prioritizing major threatening factors, which might help to halt further degradation of environment and to set appropriate conservation and managements action to protect further species and natural resource loss in the region.

Table 6 Major threatening factors of medicinal plants

Herbalists frequently assert that they used to gather therapeutic plants close to their homes in the current study area. Currently, nevertheless, gathering TMPs is difficult due to the loss of surrounding forests and drought caused by climate change is hurting the local ecology and medicinal plant species. According to several reports from different regions of the nation, these concerning features indicate common issues [30, 33, 51, 58].

Conclusions and recommendations

The present survey is the first ethnobotanical study to record the medicinal plants of the Gamo people in the Boreda Abaya District of southern Ethiopia. Traditional knowledge of medicinal plants used by Gamo people has been documented for future research and contributes with significant remarks for updating the country's knowledge of medicinal plants. It also highlights the importance of traditional medicine in the primary health care system. Identifying potential therapeutic species might promote protection of local health care and used for further studies. Documentation of this valuable knowledge will aid in preserving traditional medicine practices, conserving threatened species, and contributing to potential drug discovery in the future. In addition, exploring unassessed area aids in enriching flora and cultural uses of medicinal plants, which aids to compile herbal medicine of the region. The diverse array of medicinal plants, along with their traditional applications, provides a valuable foundation for further exploration, conservation, and potential integration into modern healthcare system. This could be possible through identification of essential therapeutic species and investigation of pharmacological and biological activities. This could enhance local and national health system and promote further scientific research. The present study also highlights the role of traditional knowledge in conserving biological resource.

The present study highlighted about188 medicinal plant species used by local communities utilized for human and domestic animal ailments in Boreda Abaya District. Traditional knowledge of using, preparing, and applying remedies for these medicinal plants was documented. The information might be useful as the baseline for future investigation of new medicinal resources. Many Gamos medicinal plants are herbaceous and harvested from the wild. Gamo herbalists frequently utilized the leaves and seeds of different species. Men have a greater role than women in traditional medicine due to cultural perspectives. Higher proportions of residents were farmers and illiterate and had more ethnobotanical knowledge than educated and young people. This might relate to their exposure and experience, and it indicate formal education is scarce. A higher number of taxa (Nt: 61) were utilized to treat the dermal disease category (ICF: 0.2), while fewer taxa (Ur: 21) were used for the genitourinary disease category (ICF: 0.16). Skin-related disease and wounds are two major conditions having higher use reports in the present study area. Among other recorded species, Ocimum lamiifolium (56 use reports), Moringa stenopetala (51 use reports), Acmella caulirhiza (41 use reports), and Croton macrostachyus (40 use reports) have higher use reports for healing different diseases, indicating their effective healing potential. It is time to conduct and widen the pharmaco-chemical studies and safety tests of Gamo medicinal plants.

Further isolating and characterizing the chemical compounds and pharmacological tests are necessary for species having higher use reports. Conservation agencies and local governments should focus on traditional medicinal plant conservation and documentation of the people's cultural knowledge of ethnobotany. Providing conservation priority, promoting conservation methods like field gene banks, Arboretums, and Botanical gardens, and supporting traditional healers might help halt the rapidly diminishing medicinal plants. Furthermore, more public awareness is needed to encourage the local people to manage and sustainably utilize medicinal plant resources.