Ethnobotany of medicinal plants in Ada’a District, East Shewa Zone of Oromia Regional State, Ethiopia

Background An ethnobotanical study of medicinal plants was conducted in Ada’a District, Eastern Shewa Zone of Oromia Regional State of Ethiopia. The objective of the study was to identify and document medicinal plants and the associated ethnobotanical/ethnomedicinal knowledge of the local people. Methods Relevant ethnobotanical data focused on medicinal plants and traditional herbal medicines were collected using guided field walk, semi-structured interview and direct field observation. Informant consensus method and group discussion were conducted for crosschecking and verification of the information. Both descriptive statistics and quantitative ethnobotanical methods were used for data analysis. Results We documented 131 species distributed in 109 genera and 54 families based on local claims of medicinal values. Patients who are using traditional drugs and herbalists collect most of these plants from the wild. The leading plant families that encompass large medicinal species were the Lamiaceae (14 species) followed by Asteraceae (13) and Solanaceae (7). Conclusion The study reported the existence of a number of medicinal plants, an indication for the presence of plant-based traditional medicinal knowledge transfer that survived through generations. Informants asserted that wild growing medicinal plants are under threat due to increased use pressure coupled with unsuitable harvesting that frequently targets roots and barks for remedy preparations. This calls for urgent and collaborative actions to keep the balance between medicinal plants availability in the wild state and their utilization by the community. Furthermore, the study attempted to prioritize the most efficacious medicinal plants as perceived by the local people for possible pharmacological testing


Background
Ethnomedicine studies the traditional medical practice and is concerned with the cultural investigation of health, disease and illness and also addresses the healthcare seeking process and healing practices [1][2][3][4][5]. Traditional methods of healing have been beneficial in many countries with or without access to conventional allopathic medicine. Ethiopia, is extremely heterogeneous ecologically [6][7][8] being a land of topographic diversities [9] and home of multiple ethnolinguistic groups [10]. Moreover, it is known to be a land for the origin of both human kind [11] and plants including crop species [12]. Thus, no wonder that it has diverse indigenous cultures that are carried over from past generations [9,13]. One aspect of this indigenous knowledge that began since time immemorial and applied for treating various ailments of human beings and domestic animals is herbal medicine. In agreement with this observation, various magico-religious literature sources [14,15] have noted that Ethiopia has a long history of applying traditional medicines for combating various ailments of humans and livestock.
In Ethiopia, traditional medicine is an integral part of the local culture and is a major public health system [16,17]. In addition to its deep cultural rooting, one reason for this is inaccessibility of modern healthcare services.
According to the Health Sector Development Program (HSDP) of the Ethiopian Ministry of Health, the national standard is given as one hospital for 100, 000 people; one health centre is for 25, 000 people and one health post is for 5,000 people. On top of this, the country faces shortage of allopathic health professionals and the ratio of one doctor is for 10, 000 people; one nurse is for 5,000 people, one health extension worker is for 2,500 people [18]. Thus Traditional medicine (TM) is an important means of primary healthcare for achieving the goal, 'Health for all'. The various literature sources available also support this fact where more than 70% of human and 90% of livestock population in Ethiopia depend on traditional medicine [19][20][21][22][23]. This tells us that medicinal plants and knowledge of their use provide a vital contribution to human and livestock healthcare throughout Ethiopia.
Similar to elsewhere in Ethiopia, people living in Ada'a District have also traditional practices which they put into effect for generations to take care of themselves and their livestock health. On the other hand, the area has been losing its indigenous flora due to the on-going human and natural causes [24]; and this loss of flora is associated with the missing of important indigenous knowledge on the plants and the traditional medical system. In strengthening this thought, several authors [25,26] noted that intense utilization of forests endangers the revival of the natural vegetation, in general and medicinal plants in particular; thus studying the ethnomedicine (herbal medicine in particular) could be considered as one of the conservation efforts in addition to other benefits in the context of driving many useful experiences for new scientific findings/innovations.
Though we have these facts, literature survey on the ethnobotanical investigation reveals that there is no previously conducted documentation work in any place in the District. Hence, there is a clear need to conduct ethnobotanical study of medicinal plants in the area, to look into and compile relevant information and to document them before the plants become too scarce to capture the knowledge of the indigenous people; and hence this study was initiated.

Study area
This study was conducted is Ada'a District which has a total area of 96, 680 hectares. The area is one of the thirteen Districts in East Shewa Zone of Oromia Regional State of Ethiopia ( Figure 1) and is located in the Great Rift Valley [24]. The relative location of the District is at about 45 km southeast of Addis Ababa, capital of the country. The District's geographical location as indicated by the Ethiopian Mapping Authority (EMA) satellite image is 08°44′E latitude and 38°58′N longitude with an altitudinal range of 1540-3100 m a. s. l. [24,27].

Sampling design
Out of the 27 Kebeles (the smallest administrative units) in the District, 15 (Chelebaselase, Dere, Dereshoki, Gerbicha, Godino, Golbo, Hidi, Hidideko, Kajimanadibayou, Kality, Koftu, Kurkuranadembi, Tuludimtu, Wajitunadebandebe, Yererselase) (55. 6%) were used as sampling kebeles for data collection. The selection of the 15 kebeles was made by purposive sampling based on the availability of traditional healers identified with the assistance of local authorities and elders. Within each kebele localities were identified based on eight habitat criteria (Forest lands, woodlands, grazing lands, fallow land, grasslands, wetlands, cultivated farm land, and home gardens). This procedure gave 140 total localities from which 101 sampling units were selected by taking one locality for each habitat type in each kebele using the lottery method (Table 1). This stratification procedure gave 8 forest land localities, 15 woodlands, 7 wetlands, 11 grasslands, 15 croplands, 15 grazing lands, 15 fallow lands and 15 home gardens that were employed for the collection of relevant data. The selection of localities based on stratification by habitat type was chosen as it is the best representative sample for capturing the medicinal plant and ethnomedicinal knowledge in the District. It is noted that not each kebele was represented by each of the habitat types.

Informant selection
Informants whose age ranged from 18 to 85 were chosen both purposively and randomly from among those born or have lived there for most of their lives. A total of 105 informants (69 males and 36 females) were used from 15 kebeles (7 informants per kebele). Sixty of the total informants (4 per kebele) were randomly selected. This was done in various ways. Some of them were chosen by tossing a coin and using him/her as informant whenever head of the coin was up if s/he volunteered to participate. Some others were chosen accidentally during random walk made to houses in the selected areas. The other 45 of the total informants (3 per kebele) were local experts (key informants) that were selected purposively based on recommendations from the local people, local authorities and development agents (DAs) at each study site.

Ethnobotanical data collection
For ethical reasons, data were collected in the presence of local administrators and with the consent of each informant for the publication of the research and any accompanying images. Materials used for data collection were mainly plant press for specimen collection, Garmin GPS 72 int'l, digital photo camera and Walkman tape recorder. Ethnobotanical data collection was undertaken during two rounds of field visits during September 2009 to June 2010. The methods employed in the data collection were group discussion, semi-structured interviews, field observation, market survey, scoring and ranking. A checklist of semi-structured questions consisting of issues was prepared in advance. The interviews were done on and around this checklist and some issues were raised depending on responses of informants. During the course of the study, each informant was visited 2-3 times in order to validate the reliability of the ethnobotanical information. The visits were done without planned appointments with the informants. Consequently, the responses of an informant that were not in harmony with each other were considered vague and discarded from the analysis.
Field walk with guides and traditional healer(s) were made during the feasibility study. Group discussions, which were employed in each kebele, were used for cross-checking and verifying the information that has been gathered from individuals by semi-structured interview. The discussions were made with key informants, other traditional healers and the local people sometimes altogether or alone in their categories during field study; and that information was recorded using tape-recorder.

Plant identification
Voucher specimens of medicinal plants that were reliably reported two times or more during informant visits were collected with the exception of some very common cultivated plants which were identified in the field. These specimens were gathered from the wild, from home gardens and crop fields and preliminary identification of these specimens was made in the field; and they were pressed and taken to the National Herbarium (ETH) of Addis Ababa University (AAU) where they were dried, deep frozen and identified. The identifications were done first using keys of published volumes of the relevant Flora of Ethiopia and Eritrea, and later supported with identification by comparisons with already authenticated specimen in the Herbarium. At last, they were confirmed with the help of taxonomic experts in Addis Ababa University (AAU); and all these voucher specimens were deposited at the National Herbarium.
Fidelity level/Species consensus has also been employed to rate the comparative curative capacity of reported traditional medicinal plants (TMP); and it was calculated by applying the formula: FL ¼ Â 100 where S f refers to frequency of citations f or a specific ailment; T f refers to total number of citations of that species. In this analysis, the consensus report of a species for treating a particular disease is seen with the report of that species for treating any given disease in the district [30,31].

Diversity of medicinal plants (MPs) in the study area
A total of 131species of MPs were gathered that were grouped under 109 genera and 53 families (Table 2). Of these plants, shrubs took the highest proportion (39%) whereas lianas took the least proportion ( Figure 2).

Plant parts used for remedy preparation
Various plant parts were reported for remedial preparation in the District (Figure 3). Roots were found to be the most familiar plant part for remedy preparations (74 species, 38.34%) followed by Leaf (65 species, 33.68%), fruits (12 species, 6.22%) and many other parts (42 species, 32.06%).

Treated ailments and frequently reported medicinal plants
The MPs reported from the study area were used to treat both human and animal ailments. Among the documented MPs, 85 (64%) were those claimed to be used to treat human diseases (Table 3), 19 (15%) to treat livestock ailments (Table 4) and about 27 (21%) to treat both livestock and human diseases (Table 5). Among the medicinal plants, Allium sativum, Rubia cordifolia, and Ruta chalepensis were claimed to be the most frequently used medicinal plants as evidenced by the higher number of informant citations (Table 3, Table 4, and Table 5). Details on the mode of preparations and applications of remedies are given in the appendix (Appendix 1).

Preparation of remedies
Interview carried out with most of the healers of the study area revealed that herbal medications were prepared differently. They often have a preference of mixing two or more MPs so as to avoid or minimize side effect of the remedies. Most of the remedies were prepared in the form of concoction whereas one species (Heteromorpha trifoliata) was served as medicine without processing ( Figure 4). Field observation revealed that healers use debarking, for instance Prunus africana, and uprooting, for example Asparagus africanus, as cases of unfavourable means of herbal collection for remedy preparation ( Figure 5).

Routes of application
The herbal drugs following preparation were reported to be administered in diverse routes ( Table 6). The routes and method of applications in the study sites varies with the type of disease treated and the actual sites of the ailments.

Conditions of medicine preparation
Most commonly, the local people asserted that they prefer the fresh plant part than the dried part for remedy preparation. Among the total MPs, 110 (57.89%) were used in the fresh form, 77 (40.53%) were used in the dried form. Only three plants (2%) were reported to be used in either form.

Dosages and other related prescriptions
In this study, provisions of doses vary with age. Such cases were not noted for gender variations. Dose of decoction is measured in various ways (see Figure 6) including tea or coffee cups (small for children, and large-sized for youngsters), JOGE (known to be equivalent to a litre), glass for local liquor (locally called YEAREKE MELEKIYA), local alcoholic beverage cup (TELLA cup), and ANKOLA (a traditional cup made of dried fruit of Lagenaria siceraria). Powdered herbal materials were measured roughly on the palm described as BETAT (i. e., measured by holding the powders between the thump and next (index) finger). Visual observations during herbal preparations showed that palm sanitation of herbalists and container was not considered. Healers also prescribed a particular dose to be taken once, twice or three times per day after carrying out traditional physical examination like looking to patients palm or eye.

Methods of applying treatments (Forms of therapy)
The documented MPs were used to treat the reported ailments by applying in various ways ( Figure 7). Most of the diseases that are inexplicable in the scientific world, like demon possession (GANEN), Evil eye (BUDA), depressions (EJE SEB) were found to be easily treated by healers; and medications were given in the name of WAAQAYOO/REBBY (a local term to mean the almighty God).

Habitat and sources of medicinal plants
Among the whole MPs, 73 of them (55.72%) were collected from the wild, 28 (21.37%) from home gardens (HGs), 20 (15.26%) from both wild and cropland and 9 species (6.87%) from both wild and HGs and the remaining one species, Myrtus communis, was recorded from open market in the District. Those MPs that were obtained from both wild environment (such as forests, grassland, wetlands and so on) and croplands were found as naturally growing plants; and it was observed that they were open for any local people who need to use them. However, those MPs obtained in home gardens were primarily grown for the purpose of foods, as spices, for marketing, as fences, stimulants, and ornaments. In the open market the MPs were usually found in relation to seeds and fruits of spices and herbs.

Most important medicinal plants
Ranking and scoring method is very helpful to compare and judge widely applicable MPs that have been assured through frequent citations. The results of simple preference ranking by key informants on five most cited MPs against blackleg are shown in Table 7 and direct matrix ranking of five most common multi-purpose MPs are given in Table 8.

ICF and FL values
Calculation of ICF values showed the most effective medicinal plants against the common illness category of the   District. Accordingly, seven disease categories that turned out ICF values greater than 0.78 were noted to be the more prevalent health problems in the District ( Table 9). The highest plant use citation was recorded for the diseases categorized as gastro-intestinal disorders. FL is an important means to see for which ailment a particular species is more effective; and accordingly this study found ten plants (Table 10) having higher healing potential (FL > 55%) in the context of the local people to treat ailments.

Medicinal plants and their occurrences in the study area
The study area yielded 131 MPs used in the traditional medical lore of the people in Ada'a District. Some of the MPs recorded from the study area were also reported by other studies to be used in the medicinal lore of other areas in Ethiopia, and it is summarized in the table below (Table 11).
The finding of such a large number of MP species in this study area is an indication that there has been a continued transfer of plant-based traditional knowledge for generations. Moreover, highest level of shared documentation of this study was observed with [32] sharing 80 herbals in common. This is perhaps because Jeldu [32] and Ada'a district are parts of Shewa highland of Ethiopia and the people belong to the same oromo community known as Tulema where it is highly likely that they have shared norms, cultural beliefs and traditional practices.
The leading plant families that were found to encompass more numbers of medicinal plant species were the Lamiaceae, Asteraceae and Solanaceae in that order. These families are among the top plant families to contain largest medicinal plant species as reported from other parts of Ethiopia [33][34][35]. This could also be linked with the fact that they are reported to be among the top fifteen plant families in the flora area, Ethiopia and hence expected to contain widely distributed species in the District [36].
With regard to the growth form of medicinal plants, shrubs were found to be the widely used form followed by herbs, trees and climbers. This pattern of growth form was also reflected in other studies conducted elsewhere in Ethiopia [32,33,35,[37][38][39][40]. The higher frequency of using shrubs and herbs may be due to the fact that the area is part of the wooded grassland ecosystem of the Rift Valley [41] where shrubs and herbs are leading growth forms than trees. This study also showed that most of the medicinal plants are collected from the wild environments (55.72%) and only one species, Myrtus communis, was recorded from open market place in the District. The wild habitats as a main occurrence site of medicinal plants are also reported in other ethnomedicinal researches conducted elsewhere in Ethiopia [33][34][35][38][39][40]42,43]. This shows that the people largely   This study also revealed that mixing of two or more MPs are common practices in remedy preparation. This is in agreement with other findings in Ethiopia [9,13,38,42] where most traditional remedies were prepared by mixing components of two or more plants. Such practices may add the healing potential and minimize the side effect it may inflict on the patient. Similar inference has also been stated in the study outputs of different ethnomedicinal researchers [9,13,33,34,38,42,44,45]. On the contrary, this current finding indicates that only few remedies were made from single plant preparations which deviate from the findings of other reports [37,46] where most of the traditional drugs in Bahirdar Zuria and Ada'ar districts respectively were made from single plant preparations. Most often, the local people of Ada'a district prefer the fresh plant part over the dried part for remedy preparation. Similar findings were reported in other areas of Ethiopia [32][33][34][35]37,38,42,[44][45][46][47][48][49][50][51] and elsewhere [52][53][54][55][56][57]. This practice agrees with the scientific fact that the healing potentials of the plant are greater when fresh plant material is used for medicine preparation because the important chemicals are expected to be more and unchanged to other forms as they do when dead and dry resulting in the decline or disappearance of the active principles, usually intermediate metabolites [58].
This study reported the routes and methods of applications in the study sites varied with the type of disease treated and the position where it occurred. The most common route of applications found in this study was oral followed by dermal. This may tell us that the widespread diseases are those that are occurring internally than on the external parts of the body. Similar finding were also noted in other studies [32][33][34][35][37][38][39][40]42,43,46,50,51,53] among many others As in most other studies, for example [33,35,43,50], roots were found to be the most familiar plant part for remedy preparations followed by leaves and fruits. Since the root is the most utilized part for remedy preparation, under intensive utilization mode it may attribute to the death of the mother plants and to the loss of the natural vegetation of the area in more severe cases. Moreover,   this current finding also noted that the total above ground part (2.1%) and the whole plant (1.6%) are also parts of MPs used for remedy preparation. For example, the entire above ground part of Eleusine floccifolia was used to treat snake bite. Moreover, above ground part of Foeniculum vulgare was reported to treat urine retention. Powder made from the above ground part of Foeniculum vulgare was reported to treat stomach trouble. Planting whole plant of Heteromorpha trifoliate at the back and front yard of the house by a diviner (METSE-HAF GELAC'H) was reported to save them against warding of sorcery and attack by magical thieves (SELABI). The whole plant body of Rumex abyssinicus was reported to treat animal scabies (EKEK). Burning the whole plant of Artemisia abyssinica and fumigating with the smoke was reported to treat itching eyes.

Local diagnosis, dosages and other related prescriptions
For some diseases like stomach trouble, cough, stabbing pain and the likes local people easily diagnose, and treat them using self-prepared conventional medicines. But mostly they visit herbalists for some chronic ailments in a similar manner as reported by Kassa [32]. The also showed that the herbalists in the study area made diagnosis like that of the modern physicians that is accompanied first with case-history taking followed by physical examination. Some physical examination includes looking to the patient's eye, or patient's palm. Then they relate the examinations with their work experience, and infer the type of ailments and prescribe the medicine. This may at times result in wrong conclusion of ailment types and provision of local drugs that are uncalled-for. In this study area, provision of doses varies with ages and ailment condition of the patient. Dose is not measured with standardized cylinder or balance. For instance, the root of Achyranthes aspera would be cut to parts simultaneously saying 'cut the blood of so, i.e, the name of the patient', and infused with brown tef (Eragostis tef ), black malt and Rhamnus prinoides and provided to the patient to drink the infusion for three days to treat RH case (SHOTELAY); and the dose is measured by local containers (JOG or ANKOLA) and taken per day. A concoction of the root and leaf of Justicia schimperiana ground together with the roots of Prunus persica, Nicotiana tabacum and phytolacca dodecandra is drunk for at least a week to treat rabies. Here one tea cup per day was reported to be enough. Root and fruit of Lagenaria siceraria pounded together and drunk with the first boiled coffee (ABOL BUNA) using coffee cup may be enough to treat impotency (SINFET WOSIB). Leaf of Hygrophila schulli was reported to be powdered and the powder will be held between the thump and next (index) finger and dispersed on the wound to treat wound poisoning. Lack of consistency was also reported elsewhere in Ethiopia [33][34][35]44,48,49] as a serious weakness in the delivery of traditional herbals.
This study also revealed that palm sanitation of herbalists and container was not considered which could  expose the drugs to contamination and thus may result in some other complications when the treatments are particularly given orally. Healers recommended not only the doses but also prescribe in how long the remedies have to be taken. Some medicines were recommended to be taken only when the patient feels the pain, or twice or three times (equivalent terms in allopathic medicine are TRN, BID and TID, respectively) in a day or days [59] and still others for a week or weeks. Some of these local drugs may be taken in the early morning before getting meal or after; some are taken early morning before urination and still others before beginning any conversation with people. Herbalists also have antidotes that are given if the herbals inflict side effects. Similar findings were reported in other studies [9,22,45,48].

The most important MPs
Those plant species obtained through ranking by key informants have been placed in the category of priority species for any further action. Cyphostemma adenocaule was reported to be the most widely used plant for treating blackleg. The reasons for showing preferences may be linked with their indigenous knowledge and availability of the plants in close vicinity of the villages in the study area. Among the very common medicinal plants direct matrix showed that Olea europaea subsp. cuspidata was found to be most important in its multiple utility value similar to the findings of Lulekal et al. [38]. From the preference ranking it could be understood that the most favoured species is usually most efficacious at least in the context of the local people and may indicate the occurrence of bioactive chemicals responsible to ward off the causative agents, and it shall be further screened in scientific works for its pharmacological potentials.

Degree of consensus on herbal medicines
ICF values are important guides to identify more efficacious plants; and through that way they also tell the level of prevalence of diseases in the District. This is because the traditional healing practices normally focused on the most frequent health problems. Accordingly, retained placenta, skeleto-muscular disorders, febril illness and general malaise, circulatory disorders, gastrointestinal disorders, urinary disorders, and gynaecological disorders, which turned up the highest ICF values (1.00-0.78) and hence these are the most prevalent ailment categories in the area. This finding deviates from the results obtained by Kassa [32] who found retained placenta among the least incident diseases while sudden illness and general malaise came among the most prevalent diseases. More prevalence could be linked with economic poverty and poor sanitation problems. Moreover, the dominance of retained placenta may show the lack of awareness and distribution of allopatic contraceptive methods in the District. Those plant species reported to be efficacious for the common health problems of the District are expected to be an input for pharmacologists to check the efficacy in vitro.
FL is an important means to see for which ailment a particular species has more healing power and accordingly those species with high FL are supposed to be

Threats of medicinal plants in the study area
Some of the MPs reported by the local people to be threatened are also included in the IUCN Red lists [60]. Inula confertiflora, which is under the near threatened (NT) category and Otostegia integrifolia, which is under the vulnerable (VU) category of the IUCN Red List are the common ones. Among those in the least concern (LC) category, Solanecio gigas and Lippia adoensis are the MPs recorded from the study area. Other MPs of Ada'a District including Acacia abyssinica, Impatiens rothii, Jasminum stans, Laggera tomentosa and Urtica simensis are endemic species [60][61][62][63], which are among the common threatened MPs in the study area. Juniperus procera, Olea europaea subsp. cuspidata, Dodonaea angustifolia, Embelia schimperi were reported to be locally threatened MPs in need of conservation efforts even if they are not under IUCN Red Lists.