The results of the current study showed that Aseko District has relatively rich in medicinal plant diversity where 96 plant species belonging to 90 genera and 67 botanical families were identified Results indicated that traditional medicine is still playing a role in meeting the basic healthcare necessities of the peoples and their livestock. Good vegetation cover, acceptance of traditional medicine, Efficacy, Cost and limited access to modern healthcare facilities could be among the factors that have made people be more reliant on local MPs. The wide uses of these plants indicate that there is a good consensus on the effectiveness of their medicinal belongings.
The finding showed that knowledge of MPs is passed mainly through family relation like everywhere else in Ethiopia [38–40]. Social relations and religions also assist in the diffusion of MPs knowledge among the rural communities. This is particularly true for MPs that are used to treat common ailments such as fibril, headache, and abdominal complaints. However, under difficult cases the community members often contact the specialist healers. Due to the belief held among the community, ordinary people do not use the MPs that are on use by the healers since it is believed that doing so will lead to the loss of MPs healing power. Such restrictions assist in MPs conservation since social restrictions serve to limit MPs harvesting. Melesse Maryo et al. [39] reported similar idea.
Results have also proved the role played by traditional MPs and the local community holding considerable traditional health knowledge in assisting the primary healthcare needs of the District community. The number of MPs harvested in the District is found to be lower than that of other area in the country investigated for their ethnomedicinal wealth [12, 41] and higher than that of other areas in the country investigated by [40]. Although cultural, economic, ease of accessibility and efficacy related factors might have played major roles for the people of Aseko to rely on traditional medicine, the cultural factor might have been the most important one resulting in a sentimental devotion to the ancestral medical traditions/practices by continuation it as a highly valued heritage of the society or of the great fathers and mothers.
Dominance of medicinal plant species from families, Solanaceae, Lamiaceae, Fabaceae and Euphorbaceae could be attributed to their wider distribution and abundance in the flora area [50–58]. This is also confirmed by consistent recording of ethnomedicinal uses of species from the above-mentioned families in different Ethiopian ethnobotanical inventories [9, 12]. Most MPs used in the area (39.6%) were found to be herbs. This could relate to the fact that they are easily accessible in the nearby areas than trees and shrubs often harvested from patches of forests distantly located from resident areas. The finding agrees with the general pattern of dominance of herbaceous species seen in most medicinal plant inventories in Ethiopia and other countries [9, 40, and 42]. Wild habitats of Aseko were found to be major pools of traditional MPs providing about 70% of all reported MPs. However, the investigation showed that these habitats are subjected to anthropogenic impacts and consequently lessening in size due to an ever-increasing population pressure resulting in the loss of many medicinal species sheltering in the wild. The current finding is also in agreement with previous reports of overdependence on wild habitats to harvest MPs [13, 26, and 42] than an effort to cultivate and use them sustainably.
In this study, leaves are the most frequently utilized part of plant organs (44%). Analogous results on different ethnobotanical studies by [43–46] were reported in different area. It was also observed that residents have been using leaves to identify MPs. Gathering leaves could be promoted as a more sustainable method since in most cases at least a number of leaves are left over on the mother plant which then allows them to carry on its life functions. As roots of medicinal plant species were reported to be harvested for most remedy preparations (19%), next to leaves, overexploitation of entire root parts for remedial preparations shows the threat posed on long-term survival of corresponding MPs. Mining of root parts of MPs was also commonly reported by other ethnomedicinal records elsewhere [12, 26, and 30]. Harvesting of roots kills the parent plant and could be a severe threat for survival of the often rare and slowly reproducing MPs of the area. Ermias Lulekal et al. [12], Fikru Ayana [42] also reported that utilization of the root part is risky to the survival and ecological aspect of the plant.
Results also showed prominent use (58.5%) of freshly harvested plant parts for traditional remedy preparation used against various ailments. The persistent use of freshly harvested medicinal plant materials in the area is reported to be related to the notion of achieving high efficacy using active ingredients of fresh plant parts which they thought could be lost on drying. This is because of the fact that the content or ingredients may be lost or reduced when the plants became dry. However, fresh collection could threat MPs since local people have no habit of preserving dry form of traditional medicine in most cases. Other ethnomedicinal inventories [35, 40, and 46] have also indicated wide use of fresh plant materials for remedy preparations due to reportedly better efficacy related factors than using dried plant materials.
The dominant use of medicinal plant Crushing (20%) and Pounding (19%) for various ailments might be related to their proven effectiveness over many years of trial and indigenous knowledge accumulated on efficacy of such preparations. The results of the study are similar with other studies done by different authors in different parts Ethiopia [40, 47, 29, and 36]. But they disagree with the results of Ermias Lulekal et al. [12] who indicate the dominant preparation in Ankober district is decoctions for various ailments might be related to their proven effectiveness over many years of trial and error indigenous knowledge accumulated on efficacy for the particular community.
The fact that most remedies in the study area were applied orally (54.41%) followed by topical or dermal application (29.42%) could be due to the high occurrence of gastrointestinal and dermatological disorders in the study area (Appendix 2 additional to be attached). Predominance of oral and dermal routes of herbal drug application in the study area could be because of high prevalence of gastrointestinal and skin related problems in the area. Dermal of remedial application could also be attributed to the fact that it reduces the chance of intoxication by drugs than when it is administered orally. In addition, both oral and dermal routes permit fast physiological reaction of prepared medicines with the pathogens and upturn its curative power. Patients with skin infections were reported to be treated by rubbing and pasting herbal preparations whereas those with sores were treated by chewing the part of the medicinal plant and spitting the juice on the sore. For internal ailments, herbal preparations were mainly prescribed to be administered orally whereas for a general malaise steam bath and vapour inhalation were commonly reported. In connection to this, reports showed that oral and dermal route of administration of remedies found to enhance the physiological reactions of remedies with the pathogens that in turn increase the healing power of the medicine. In this regard, similar findings were reported away [7, 61; 62].
The number and different types of diseases (55 disease types) (Appendix 1 additional file tobe attached) for which traditional healers were most visited by patients indicated a liking of local people in the study area to visit traditional healers and the nature dispensary. Economic, cultural, efficacy, limited access to modern medicine and availability factors were reported as the key factors which lead the community to hit at the door of traditional healthcare practitioners than the few distantly located healthcare centers with unaffordable prices. Similar findings were reported by [9, 46, and 12].
Visual checkup of patients is the more obvious diagnostic method practiced by all local healers in the area. Although changes in body temperature, skin and eye color, appetite and physical appearance help traditional healers to detect which patients face sicknesses it was only through visual experience that identification of diseases and prescriptions look like to be made. Other researchers [11, 46, and 12] have also reported similar diagnostic methods in different cultural groups. Misidentification of diseases commonly leads to misprescription which may result in adverse effects to patients. Even though dosages of remedies for various ailments were reported to be determined based on age, occurrence of pregnancy, physical fitness/appearance and gender of the patient, there were no standardized measurements or guidelines set by traditional healers.
Overdose of remedies was also reported to bring adverse effects like vomiting, diarrhea, burning sensations and sometimes fainting of the patient. Lack of precision and standardization has been mentioned as a global drawback of the traditional healthcare system [22, 12] Traditional healers in our study area reported the use of different antidotes including BESSO, milk, coffee, honey, yoghurt, and butter for reversing adverse effects and stabilizing any disorder. The same pattern of using antidotes was also reported for other cultural groups elsewhere [25, 26, 33, and 12].
The results from market survey of MPs indicated that most MPs (74%) have no marketability report and were not available on major market places of the District during the time of research. This would show that the majority of MPs are collected from the wild for remedy preparations only when the need arises. Although 26% of the MPs were available on the market Echinops kebericho, Embelia schimperi, Hagenia abyssinica, Withania somnifera and Silene macrosolen were the only ones to be sold or purchased for their traditional medicinal uses. The market value of these species (with a price range from 0.27 USD per bunch of root or jug of inflorescences to 0.4 USD for a cup of fruits) showed the income generation potential of a number of MPs and gives an indication of potential demand of those marketable plants by the community. However, such marketability could also indicate that the plants are under pressure since they are purposefully hunted for income generation. Other reportedly marketable MPs of Aseko were mainly gathered and sold for their uses related to edibility, spice, stimulants, lumbering, firewood, and construction purposes. Although the investigation indicated current market potential of MPs in Aseko, a relatively wider domestic trade of Ethiopian MPs was reported for other cultural groups in the country [13, 48, and 22]. Thus, our finding can also be used as a base line for a future in-depth study of the moneymaking potential of MPs of the area through successive market survey over number of years and value chain analysis study of potential plants.
The highest recorded ICF values (0.76 and 0.74) indicated best agreement among informants on the use of medicinal plant species reported to be used for treating gastrointestinal, and parasitic and febrile illnesses, respectively. The observed highest informants’ agreement coupled with high plant use citations for these disease categories could also indicate the relatively high incidence of the latter diseases in the area. According to [23], high ICF values are important to identify plants of particular interest in the search for bioactive compounds. Accordingly, about 9 MPs of Aseko (with high ICF values) for treating gastro-intestinal and parasitic diseases are under investigation for their pharmacological properties by our research theme.
Andrade-Cetto and Heinerich [24] reported that lower fidelity level indicates a given medicinal plant species could have more number of mentions by the informants than medicinal plant species that have high fidelity level. The fact that MPs had the highest FL values could be an indication of their good healing potential at least with the local population. According to Trotter and Logen [30] plants that are used repeatedly are more likely to be biologically active as MPs. Confirmation or consensus could not be taken as a single measure of the potential efficacy of any medicinal plant. Thus, efficacy is not the only factor that influences the informant choice but the prevalence of a given plant and disease in the area can affect informants’ choices.
The reported highest fidelity level values for Ocimum gratissimum L against febrile diseases, Rubus steudneri Schw against Asthma and Podocarpus falcatus against Intestinal Parasite (100%FL) each, could be considered as a clue for the high healing potential of these plants against the corresponding diseases. Plants with highest fidelity level values could also be targeted for further phytochemical investigation to prove the bioactive components that are responsible for their high healing potential [12, 30].
The output of a direct matrix ranking exercise showed highest values/ranks for a number of multipurpose MPs of the study area including Cordia Africana, Hagenia abyssinica and Podocarpus falcatus. The result indicates that these plants are exploited more for their non-medicinal uses than for reported medicinal values. Thus, the result calls for an urgent complementary conservation action to save the fast eroding multipurpose medicinal plant species of the area. Yineger et al. [49, 12] has also reported the same pattern of highest exploitation of multipurpose MPs for uses other than their traditional medicinal importance in south eastern Ethiopia.
The preference ranking exercise helped to identify the most-preferred medicinal plant species to treat Gastritis. Accordingly, Urtica simensis Steudel stood first, followed by Ensete ventricosum W and Linum usitatissimum L scored highest values and were found the most-preferred ones to treat the disease. Further investigation of these species for their bioactive components against Gastiritis may bring promising results.
It was also found that traditional healers show maximum secrecy in handling MPs knowledge. Moreover, they try not to outflow the knowledge out of the family circle. These facts coupled with the absence of any written document on MPs of the area show the threat on the future use of ethnomedicinal potential of Aseko.