Ethnobotanical study of medicinal plants in the Hawassa Zuria District, Sidama zone, Southern Ethiopia

Human beings have depended on nature for their simple requirements as being the source of medicines, shelters, food, fragrances, clothing, flavors, fertilizers, and means of transportation throughout their lives. Plants have been used for medicinal purposes since long before the prehistoric period [1].

Medicinal plants have made a significant contribution to the primary healthcare of people around the world. Population increases, inadequate supplies of drugs, the prohibitive cost of treatments, side effects of several synthetic drugs, and the development of drug resistance to infectious diseases have led to the increasing use of plant materials as a source of medicine for a wide variety of human ailments. Recently, the WHO estimated that 80% of people worldwide rely on herbal medicines for some aspects of their primary healthcare needs. According to the WHO, around 21,000 plant species can potentially be used as medicinal plants [2].

Africa has rich resources of medicinal plant species. Ethiopia is believed to be home for about 6500 to 7000 species, with approximately 12% of these endemic [3]. In Ethiopia, approximately 80% of humans and 90% of the livestock population rely on traditional medicinal plants to cure different ailments [4] due to difficulties in accessing modern health facilities, the cultural acceptability of healers, and low cost of traditional medicine [5].

Southern Ethiopia is the main homeland of numerous ethnicities, containing more than 45 indigenous ethnic groups who speak at least 12 languages from four linguistic families [6]. The Sidama ethnic group (19.38%) is the predominant group in the Southern Nations Nationalities and Peoples Region. They number about 4.8 million, of whom 3.9 are urban inhabitants. The main spoken language is Sidamegna (18%) from the Cushitic linguistic family [7]. The daily lives of the Sidama peoples depend on agriculture. Ensete (Ensete ventricosum (Welw.) Cheesman.), also known locally as the wesse plant, is an important staple food. Coffee (Coffee Arabica L.) is the most important source of income, and the Sidama zone is the major contributor to coffee production. The Hawassa Zuria district is well known as a maize (Zea mays L.) growing district, with other crops also grown. The people raise cattle, and there is high value attached to livestock by the Sidama. The number of cattle owned is a good indicator of wealth, and popularity increases for farmers who own more cattle. The zone is also rich in water resources, which are underutilized.

Greater numbers of medicinal plants are found in the south and southwestern parts of Ethiopia due to the high biological and cultural diversity in these regions [3, 8]. Thus far, 1000 identified medicinal plant species have been reported among Ethiopian flora, but others remain not yet identified. There are approximately 887 medicinal plant species that are currently used by the Ethiopian people. Nearly 300 of these are frequently mentioned in many sources. The majority of medicinal plants are herbs, followed by shrubs and trees [9]. Most of the medicinal plant species are found in wild forests [10]. Over 40% of medicinal plant species have enormous socio-economic value in Ethiopia, and these require further investigations [11].

Ethnobotanical studies documented in Southern Ethiopia have studied the following: the Amaro district [12], the Benna Tsemay district [13], Burji district [14], Cheha district [15], Kembatta ethnic group [16], Konsso ethnicity [17], the Konta special woreda [18], the Lemo district [19], Maale and Ari [20], the Wolaita zone [21], the Wonago woreda [3], and the Wolaita zone [22]. However, there is still limited ethnobotanical documentation on medicinal plants and relatively few phytochemical analyses of documented medicinal plants. Ethnobotanical studies of medicinal plants conducted in the Sidama zone of southern Ethiopia have focused on the Boricha district [23], the Dale district [24], Hawassa city [25], the Bensa district [26], and Wondo genet [27].

The greater concentration of medicinal plants is found in the south and southwestern parts of the country in keeping with the concentration of biological and cultural diversity [28]. This indicates that there is high traditional medicinal plant knowledge in the southern part of Ethiopia, but the indigenous knowledge has not been systematically documented in the region. Particularly, there is no ethnobotanical study in the current study area of the Hawassa Zuria district. In addition, indigenous knowledge is disappearing due to a lack of written documents about medicinal plants, the deaths of tribal elders without the transfer of traditional skills to other members of the family, the migration of people due to social problems, urbanization and modernization, and the influence of modern medicine and exotic cultures. Therefore, the general research objective of this study was to collect, identify, and document medicinal plants and to collate the associated indigenous knowledge of the Sidama people with regard to how they treat various human and livestock ailments in the Hawassa Zuria district of the Sidama zone of Southern Ethiopia. This study was also conducted with the following specific objectives: (1) to measure and compare the indigenous knowledge of the Sidama people among social groups, (2) to discover traditional knowledge gaps and threats to medicinal plants, and (3) to provide baseline data for further phytomedicine and phytochemical studies.

The most commonly used methods of remedy preparation were grinding (39%), followed by chewing and boiling (11%), eating (8%), liquid form (6%), spitting and rubbing (4%), squeezing (3%), powdering and smelling (2%), and burning and holding on the teeth (1%) (Fig. 6).

Medicinal plants were given via different routes of administration, such as oral, dermal, ocular, ear, external, and nasal. The most commonly used route was oral (74%), followed by dermal (20%). The remaining (2%) types were applied through ocular, nasal, and external routes (Fig. 7).

In this study, 105 medicinal plant species were identified for the treatment of human and livestock ailments distributed across 52 families and 95 genera. From the 52 plant families, Fabaceae (21%) was the major contributing species, followed by Lamiaceae (13%) and then Cucurbitaceae (12%). Similarly, various studies in Ethiopia [25, 38‐40] have reported Fabaceae as the most dominant medicinal plant family. In contrast, other studies found that Lamiaceae [18] and Euphorbiaceae [41] were dominant over others.

Among the documented medicinal plants, five endemic medicinal plant species were recorded. Identification of endemic species and current statuses is vital for the conservation of medicinal plants. The medicinal plants in the study area had diverse growth forms, in this case herbs (34%), trees (33%), shrubs (28%), and climbers (6%) were the dominant medicinal plants. Similarly, Lulekal et al. [38] reported that most medicinal plants were herbs in Ankober. Mesfin et al. [3] and Giday [9] also reported that the dominant medicinal plants were herbs. In contrast, the majority of medicinal plants were shrubs in the Wonago district [3]. Regassa [25] in Hawassa city indicated that the majority of the collected medicinal plants there were trees, followed by shrubs.

The results here showed that the local people of the Hawassa Zuria district use different parts of a medicinal plant to prepare remedies. Leaves were the most widely used part, making a contribution to the conservation of plants rather than harvesting the root part and/or whole plant. In the same way, Berhane [20] reported leaves as the predominant plant part used by the Maale and Ari ethnic communities. Ketema [42] also noted leaves were the most commonly used plant part in a study focusing on South Omo. The majority of medicinal plants were harvested for their leaves by the Sheko as well [9]. However, the most frequently used plant parts were roots in the Hadiya zone [43] and in Benna Tsemaye [13].

The local people in the Hawassa Zuria district use different remedy preparation methods depending on the type of disease to be treated. Cutting, tying, spraying, roasting, soaking, hanging, brushing, squeezing, powdering, spitting, and holding on the teeth were some of the preparation methods used to treat human and livestock diseases. The most commonly used method of remedy preparation was grinding (39%), followed by chewing and boiling (11%). Elsewhere in Ethiopia, similar findings were reported [13, 44] with regard to the most commonly used methods of remedy preparation. These were crushing, followed by chewing, boiling, eating, and in liquid form.

The prepared remedies were administered in different ways. Some of the routes of administrations were via the oral, dermal, and ocular routes and via the ear, externally, and through the nasal passage. The majority of the remedies were administered done so orally (74%) followed by the dermal (20%) and ocular (2%) routes. Similar findings were also documented in different parts of Ethiopia. The majority of medicinal plants were administered orally in Endrta [45]. Assegid [13] reported that the majority of plants were used in oral applications in the Tsemay district. Sintayehu [27] found that prepared remedies were widely administered orally in Wondo Genet.

In the Hawassa Zuria district, 34 human, 13 livestock, and 22 ailments of both humans and livestock were recorded. This indicated that the people of the district suffered from many ailments as compared to those in other areas, such as in the Wonago district [3] and the Bench district [9]. Moreover, a single human ailment was found to be treatable by several medicinal plants. This is in agreement with the findings of earlier studies [27, 45] that found single ailments to be treated by several medicinal plants. The present study found that 16% of medicinal plants were used to treat gastrointestinal ailments, with slightly lower rates for general and unspecified diseases (14%). Similarly, among the Sheko, 16.9% of medicinal plants were used to treat gastrointestinal complaints [9]. The highest proportions of Meinit and Dek Island medicinal plants were used to treat gastrointestinal complaints [46, 47].

The present study indicated that men, older, and literate people who attend elementary school have more medicinal plant knowledge as compared to women, younger, and illiterate people. The reason for the high traditional knowledge of men and older people could be due to the influence of modernization and a lack of interest among the younger generations. Similar findings also indicated that there are significance differences in traditional knowledge among different communities in Ethiopia [40, 48]. Unlike other studies, the current study indicated that literate people who attend elementary school reported a higher number of medicinal plants as compared to those who are illiterate.

Jaccard’s coefficient of similarity indicated that there was some similarity in the composition of medicinal plants between the study area and the Wondo Genet district [27], whereas less similarity was found with regard to the Mana Angetu district [49]. This may stem from the agroclimatic conditions of the study area.

The category with the highest ICF values was fever (malaria), followed by insects and ectoparasites diseases. The highest plant use citation was found for gastrointestinal ailments, followed by sensory neuron diseases. Similarly, gastrointestinal disorders and parasite infections were the most commonly treated diseases on the Zegie peninsula [50].

The highest fidelity levels were found for gastrointestinal ailments in this study in all cases. Eucalyptus globulus Labill. (100%) scored the highest fidelity level value. Similarly, Reta [25] reported that gonorrhea, wounds, and stomachache had high degrees of ICF and that malaria showed the highest FL in Hawassa city. Teferi [39] indicated that diarrhea and malaria were the most frequently reported diseases among the Benta ethnic group.

The output of the preference ranking indicated that Eucalyptus globulus, Nigella sativa L., and Casimiroa edulis La Llave. were the most commonly preferred medicinal plants as treatment for stomachache in human in the Hawassa Zuria district. Similar findings for South Omo showed that the highest numbers of plant species were reported to treat abdominal or stomach disorders [42]. Cucumis dipsaceus Ehrenb. ex Spach, Rotheca myricoides (Hochst.) Steane & Mabb., and Euphorbia abyssinica J.F.Gmel were ranked as the most preferable medicinal plants to treat cancer in both humans and livestock.

According to the direct matrix ranking results, Ensete ventricosum ranked first as the most preferred medicinal plant used for various purposes by the local people. The second and third most preferable medicinal plants were Olea welwitschii (Knobl.) Gilg & G. Schellenb. and Dodonaea viscose subsp. angustifolia, respectively. However, Prunus africanus is the most preferred medicinal plant for various use in Hadiya zone [43]. In the present study, Ensete ventricosum was used as a type of food, as fodder, in house construction, and for robe making. It also had cultural and spiritual value. Olea welwitschii was reportedly used mainly for purposes related to house construction, material cleaning, incense, spiritual value, firewood, and cultural value. However, the overexploitation of medicinal plants for other purposes can affect the availability and conservation of medicinal plants for their primary purpose.

According to the responses from key informants, the main causes of the loss of medicinal plants in the study area were agriculture expansion, firewood collection, environmental degradation, deforestation, construction, and charcoal creation. Other research on threats to medicinal plants in Dale [24], the Benna Tsemay district [13], the Mana Angetu district [49], Wondo Genet [27], Amaro woreda [51], and Wonago woreda [3] indicated findings similar to those here.

Other factors related to the loss of indigenous knowledge about medicinal plants were the secrecy of traditional knowledge practiced by elders in the tribe, a weak transfer system for indigenous knowledge, and the influence of modernization. Similarly, other findings [10, 27, 52‐55] reported that there is an aura of top secrecy in the passing of indigenous knowledge within families. Therefore, better conservational awareness by all community members is necessary to retain their own indigenous knowledge and to prevent the extinction of their medicinal plant resources.

The results of the study revealed that there is high diversity of the medicinal plants in the Hawassa Zuria district. One hundred five medicinal plant species were documented to treat 61 human and livestock ailments. Stomachache, headache, malaria, gastritis, mitch, amoeba, goiter, tuberculosis, gonorrhea, and urine problems were frequently occurring human ailments, whereas wounds, ticks, swelling, anthrax, evil eye, and ‘gadanesa’ were common livestock ailments. This indicates that local people depend on indigenous knowledge to prevent various human and livestock ailments.

In the study area, major knowledge differences were found among different social groups. Male informants had more knowledge than females. Older informants above 50 years of age were more knowledgeable than the young between 20 and 35 years and adult informants between 36 and 50 years. Informants who attended elementary school had more knowledge than those who were illiterate.

The main threats to medicinal plants in the Hawassa Zuria district were deforestation, agricultural expansion, and overexploitation. The medicinal traditional knowledge gap between the older and young generations has also impacted the loss of indigenous knowledge. Therefore, there should be mentoring programs for local people in the study area to conserve their indigenous knowledge resources and prevent the extinction of their medicinal plants.

Conservation of endangered endemic medicinal plants through in vitro and ex vitro propagation should be developed to protect the extinction of medicinal plants. Furthermore, the current documented information on the medicinal plants of the Sidama people can be used as baseline data for future studies of pharmacologically important medicinal plants and for phytochemical investigations.