Ethnobotanical Study of Medicinal Plants Used to Treat Human Ailments by Guji Oromo Tribes in Abaya District, Borana, Oromia, Ethiopia

Medicinal plants are the integral part of the variety of cultures in Ethiopia and have been used over many centuries. Hence, the aim of this study is to document the medicinal plants in the natural vegetation and home gardens in Abaya district, Borana Zone, Oromia National Regional State, Ethiopia. Forty eight traditional healers were selected to collect data on management of medicinal plants using semi-structured interview, group discussion, and field observation. The distribution of plant species in the study areas was surveyed. Forty three plant species were documented as having medicinal value: [21 (48.8%)] were Shrubs, [13 (30.3%)] herbs, and [9 (20.9%)] trees. The root [17 (39.5%)] was the most commonly used plant part followed by leaf [13 (30.2%)], fruits [7 (16.3%)] and stem [6 (14.0%)]. Agricultural expansion (24.4%) in the area was found to be the main threat for medicinal plants followed by fire wood collection (18.8%). Peoples' culture and spiritual beliefs somehow helped in the conservation of medicinal plants. Traditional healers still depend largely on naturally growing plant species and the important medicinal plants are under threat. The documented medicinal plants can serve as a basis for further studies on phytochemical and pharmacological studies.


Introduction
Traditional medicine is used throughout the world as it is dependent on locally available plants, which are easily accessible, and capitalizes on traditional wisdom-repository of knowledge, simple to use and affordable. These medical systems are heavily dependent on various plant species and plant based products. The current account of medicinal plants of Ethiopia, as documented for National Biodiversity Strategy and Action Plan by [18], shows that about 887 plant species were reported to be utilized in the traditional medicine. Among these, about 26 species are endemic and they are becoming increasingly rare and are at the verge of extinction. Equally threatened is the knowledge base on which the traditional medicinal system is based, as the ethnobotanical information is not documented and remains in the memory of elderly practitioners. Therefore, detailed information on the medicinal plants of Ethiopia could only be obtained when studies are undertaken in the various parts of the country where little or no botanical and ethnobotanical explorations have been made [14]. Ethnobotany tries to find out how people have traditionally used plants, for various purposes, from time immemorial [6]. Thus, ethnobotany tries to preserve valuable traditional knowledge for future generations.
The studies conducted on the traditional medicinal plants in Ethiopia are limited when compared with the multi-ethnic cultural diversity and the diverse flora of Ethiopia. Thus, this study was initiated to document the medicinal plants in the natural vegetation and home gardens in Abaya district, which assume that the data could be used as a basis for further studies on medicinal plants in Abaya district for future phytochemical and pharmacological studies.

Study sites
Abaya district is located at the northern tip of Borana zone between longitude of 37° 40' -38° 40' E and latitudes of 6° 14' -N 6° 25' N and 372 km away from Addis Ababa to the south (Fig. 1). The district is boarded by Nations, Nationalities and Peoples of Southern Ethiopia Regional State in the north and east, Lake Abaya in the west and Gelana district in the south. The total area of the district is approximately 1871.34 sq. km or 187,134 hectares, and this comprise about 2.2% of the total area of the zone and the district is further divided into 26 'kebeles' (the smallest administrative unit).  According to Central Statistical Agency administrative report (2012) Abaya district has a total population of 104,374 of which 52,547 (50.3%) are males and 51,827 (49.7%) are females. According to the data obtained from the District Agricultural Office, out of 187,134 hectares of the total area of the district, 45,928 (24.54%) hectares are known to have potential for agriculture (cultivable land), grazing land shares 60,666 (32.42%) hectares, forests and bush-land comprises 11,814 (6.31%) hectares, water bodies (Abaya Lake) share 62,925 (33.63%) hectares and others comprise 5,801(3.1%) hectares of land.
The rainfall distribution of the study area is bimodal (two rain seasons). The main rainy season is from June to September ('Kiremt' or 'Mahar') and the short rainy season is from February to April ('Belg'). The average annual rainfall is 107.72 mm and, the mean annual average temperature of the district is 20°C. The study was conducted in twelve 'kebeles' (the smallest administrative unit) in Abaya District, Borana zone of Oromia National Regional State from April to October 2013. Prior to data collection, discussions were made with elders and local authorities to select the 'kebeles' where traditional healers were found. The 'kebeles' were selected based on availability of traditional healers, and on the recommendations of elders and local authorities in the Abaya district.

Ethnobotanical data collection
Forty eight traditional healers (36 males and 12 females) were selected from the selected twelve 'kebeles' of the district based on the recommendation from elders and local authorities. The ages of the healers were between 25 years and 80 years. A brief group discussion was made with the informants at each 'kebele' prior to data collection to get their consent and to explain to them that their cooperation is a valuable contribution to the documentation of the traditional medicinal plants of the district. Interview, group discussion, and field observation were employed to collect data on knowledge and management of medicinal plants. The group discussions were conducted to elaborate the methods of preparation, administration and conservation of the medicinal plants. Interviews were conducted in 'Afan Oromo' language. During the study period, each informant was visited two to three times in order to confirm the reliability of the information. The responses that were not in harmony with each other were rejected. The information was collected about the plant names, methods of preparation and combination of herbal medicines, modes of administration and the ailment treated. Crushed seeds mixed with Allium sativum bulbs and honey is taken orally for five days before breakfast After each dose, one glass of melted butter is recommended for immediate recovery.

Malaria
Dry seed powder with crushed seed of Ocimum lamiifolium is taken with coffee as drink 'Mich' Dry seed powder with crushed seed of Ocimum lamiifolium is taken with coffee as drink Headache The reported medicinal plants were collected during the field walks and trees, shrubs, herbs and climbers were listed. Voucher specimens were collected, pressed and deposited in the National Herbarium of Addis Ababa University (AAU). The plants identification was performed both in the field, and at the National Herbarium of AAU.
A descriptive statistical methods, percentage and frequency were used to analyse the data on reported medicinal plants and associated indigenous knowledge. Plant species are enumerated (Table 1) with their family name in alphabetical order, botanical names, local names ('Afan Oromo'), habits, preparations and applications, diseases treated and voucher numbers.

Results and Discussion
Most of the shrubs were collected from woodlands, rocky surfaces, secondary forests and homegardens. The herbs were mostly found in woodlands, grazing land and farmlands. The tree species were found in open woodland, farm boarders, road sides, live fences and in coffee plantation areas. Medicinal plants like Artemisia afra L., Lepidium sativum L., Enset ventricosum (Welw.) Cheesman, Ocimum lamifolia Hochst. ex Benth. and Ruta chalepensis L. were restricted to farm lands, farm boarders, live fences and home gardens. [8,19,3] used similar approaches to identify sites of collection of medicinal plants.
Ethnomedicinal uses of 43 angiosperms belonging to 29 families and 40 genera have been documented. Among the total of forty three medicinal plant species investigated in this study, 18 species are mentioned in [17], 16 species in [20], 12 species in [8], and 28 species in [12]. In Africa, 12 medicinal species are documented by [2] and 16 by [9].
In terms of the number of species with medicinal properties, the families Asteraceae and Euphorbiaceae dominate each with 5 (17.2%) species followed by Boraginaceae, Celastraceae, Cucurbitaceae, Fabaceae, Rosaceae and Tiliaceae each with 2 (6.9%) species and the remaining 21 families each with one (3.4%) species.
The most widely used plant remedies by the people of Abaya district were obtained from shrubs (48.8%) followed by herbs (30.3%). The documented data showed that the majority of medicinal plants from natural vegetation were shrubs and herbs; they were relatively common in the study area compared to tree species. This agrees with the works of [17,8,22,12].
The most popular plant species in terms of demand and the number of diseases cured are Lepidium sativum L., Ruta chalapensis L., Kanahala laniflora (Forssk.)R. Br. and Artemisia afra Jack. ex Wild. Among commonly used plant parts, root (39.5%) is the most frequently used followed by leaves (30.2%), fruit (16.3%) and stem (14.0%).
The most widely sought part in the preparation of remedies was the root. The popularity of this part has serious consequences from both ecological point of view and from the sustainable survival of the medicinal plant species.
The various forms in which medicines are administered include powder (37.2 %), crushing and pounding (51.2%), chewing (4.65%), concoction, decoction and other each with 2.3%. The mode of preparation and application vary according to disease type.
The informants' response indicated that there were variations in dosage of remedies, unit of measurement of remedies, duration and time that were prescribed for the same kind of health problems. The major factors that determine the amount to be given were age, physical fitness, stage of illness, pregnancy and presence or absence of any disease other than the disease to be treated. [7,15,1] have also discussed lack of precision and standardization as a drawback of the traditional health care system.

Conservation and Threats of Medicinal Plants
Some traditional practitioners had started to conserve medicinal plants by growing them in home gardens. Such as Ruta chalepensisL., Ricinus communis L., Ocimum lamiifolium, Artemisia abyssinica Sch. Bip. ex A. Rich and Artemisia afra Jack. ex Wild similar to the observation made by [10]. In most scenarios, the home gardens are fenced and protect the medicinal plants from grazing and unwise harvesting.
The main threat for medicinal plants in the natural vegetation was agricultural expansion (24.4%). Most of the respondents perceived urbanization and construction as the least destructive factors contributing to 11.8% and 10.2% of the total score, respectively. Clearing of natural vegetation and expanding agricultural land were almost a daily activity in the study area. During the field study, it was observed that large number of big trees of Macaranga capensis (Baill.) Sim, Olea europaea L.. ssp. Cuspidate (Wall. ex G. Don), Pouteria adolfi-friederici (Engl.) Baehni and Syzygium guineense (Willd.) DC. were removed by the local people to prepare the forestlands for agricultural purpose. These factors combined with the natural vulnerability of the area may lead to further reduction in natural habitats of the medicinal plants. Pressure from agricultural expansion, wide spread cutting for fuel wood combined with seasonal drought is also reported in [4,12,13,11,21] as main factor for environmental degradation.
The conservation of medical plants in the study area was limited except in Juniperous-Eucalyptus dominated plantation, which was the only protected natural vegetation areas. Rather, the peoples' culture and spiritual beliefs somehow had helped in the conservation of medicinal plants. For instance, the claim of the traditional healers that medicinal plants will be effective only if cut and administered by the healers or healers' relatives had helped in the conservation of the medicinal plants. Also, the collection of medicinal plants in specific season, for example, at the end of the Ethiopian calendar year in 'Pagume' (onset of September) enabled the plants to regenerate and complete their life cycle. This is true mostly for annuals, those whose leaves, fruits and seeds are used, if other destructive pressures are kept at low level.

Conclusions
Traditional medicinal plants were harvested mostly from natural vegetation area and home gardens. They were also obtained from roadsides, farmlands and live fences. The medicinal plants in the natural vegetation were under threat and to tackle these problems traditional healers had turned their face towards home gardens. However, traditional healers still depend largely on naturally growing species because of their belief that those species in the natural vegetation are more effective in the prevention and treatment of diseases and health problems. Furthermore, the documented medicinal plants can be used as a basis for further studies on the regions medicinal plants knowledge and for future studies.