Background

People have long histories on the uses of traditional medicinal plants for medical purposes in the world, and nowadays, this is highly actively promoted [1,2,3]. Evidence from Kibebew [4] showed that traditional medicines are used by 75–90% of the rural population in the world. The report from the World Health Organization [5] revealed that traditional medicinal plants were trusted primarily by 80% of the population in Africa. Traditional medicines are more liked in developing countries due to inadequate modern health services. In Ethiopia, the use of traditional plant medicines had been practiced since the ancient time [6]. In Northern Ethiopia, the major portions (87%) of the traditional medicines are coming from plant sources [7]. However, the traditional medicines are far from the expected level of uses, safety, and efficacy in the world [8, 9]. In Ethiopia, the bulk of the medicinal plants were collected from natural vegetation, and nowadays, natural vegetation is shrinking due to environment degradation and overuses. Therefore, it is necessary to document medicinal plant species for conservation and sustainable consumption. In addition, ethnobotanical studies on traditional medicinal plants are also the means to increase the capacity of the pharmaceutical industries. However, the documented medicinal plants are still limited when they are compared with the multi-cultural diversity of the people and the diverse flora in Ethiopia [10]. In Gubalafto District, the people live in places which are grouped into peaks, highlands, middle lands, and low lands. In such diverse environments, traditional medicinal plant species and their uses are expected to be more. However, no scientific documentation on the medicinal plant resources has so far been made in Gubalafto District. If any cultural changes take place in this community and the vegetation is degraded due to various factors, the knowledge of the people on the plant resource will vanish slowly. Moreover, some of the medicinal plant species may become extinct from the District before being documented and the people may lose their uses and their indigenous knowledge on them forever. Therefore, the ethnomedicinal study on the plants of Gubalafto is crucial in order to protect the plants under ex-situ and in-situ conservation and to preserve the associated indigenous knowledge in the District and beyond. Thus, the author documented the traditional medicinal plant species and the associated indigenous knowledge used for the treatment of human ailments in Gubalafto District.

Methods

Description of the study area

Gubalafto District is found in North Wollo Zone, Amhara region, Ethiopia, by which Woldia is the main town of the District. Woldia is about 506 km far from Addis Ababa, and the main road cross it to Mekele, Dessie, Bahir Dar, and Lalibela towns. It consists of 34 kebeles, and it is situated between 39° 12′ 9″–39° 45′ 58″ East and 11° 34′ 54″–11° 58′ 59″ North (Fig. 1). The topography of the District ranges between 1100 and 3700 m above sea level (m.a.s.l) and mostly characterized by a chain of mountains (35%), undulations (30%), flats (20%), and gorges/valleys (15%). In addition, Gubalafto District is classified into four agro-ecological zones based on their altitudinal variation and climatic conditions. These are lowlands (1100–1500 m.a.s.l), middle lands (1500–2300 m.a.s.l), highlands (2300–3200), and peaks (3200–3700 m.a.s.l.). These agro-ecological zones were also known by the people as Kolla, Woina Dega, Dega, and Wurch, respectively. The mean values of annual temperature range from 7.5 to 22.8 °C and the rainfall from 22.8 to 203.7 mm in the form of bimodal (rain available in two seasons in a year) [11]. Gubalafto District has 139, 825 total population, of which 50.6% are men and 49.4% women [12]. About 3.49% of the population lives in the urban area, and the remaining 96.51%, in the rural area. People mainly depend on agriculture for their livelihoods. There are 51 health centers, of which 9 of them are private and 42 are governmental centers in the District. Acute febrile illness, acute upper respiratory infection, dyspepsia, diarrhea, pneumonia, helminthiasis, diseases of the muscular and skeletal system, trauma, urinary tract infection, infections of the skin, and subcutaneous tissues are the ten major morbidity diseases recorded in the District [13].

Fig. 1
figure 1

Map of the study area. a Location of Gubalafto District in Ethiopian. b Sampled and non-sampled kebeles in Gubalafto District. c List and site of sampled kebeles in Gubalafto District

Full size image

Study sites and informant selection techniques

Study sites and informants were selected based on the information gathered from Gubalafto District administration office, health office, agricultural office, and other people in the study area via reconnaissance survey prior to the data collection. Accordingly, seven kebeles, namely Koso-amba, Ahuntegegn, Woyneye, Geshober, Amaye-mecha, Gubarja, and Hara were selected for data collection with purposive sampling method based on their agro-ecological conditions, the availability of traditional medicine practitioners, and vegetation covers (Fig. 1). Eighty-four informants (12 from each kebele) both males and females, whose ages ranged from 20 to 90 years were interviewed during the study. Informants were selected with purposive, snowball (non-probability), and random (probability) sampling techniques following previous publications [14,15,16]. The purposive sampling technique was used due to the fact that there were healers that had an official permission for their traditional healthcare practices. Information regarding healers was obtained from each sampled kebele health offices and other people. On the contrary, the snowball sampling technique was used to get hold of healers who had no official permission for their traditional medicinal practices and who were found through the suggestion of other interviewed informants confidentially. As the names of non-legalized healers were not registered in the governmental offices and the people hesitated to report their names freely, the use of a snowball sampling technique was useful.

In the same vein, additional traditional medicinal plant species and associated information were collected from general informants (non-healers) with random sampling techniques. General informants were ordinary people who were found in the study area for a long period of time and used their indigenous medicinal plant knowledge within their families. Hence, general informants were included as respondents to gather additional data and check the transfer of indigenous knowledge within the people. Generally, purposive and snowball samples were used to choose a total of 32 key informants, whereas 52 informants were selected using random sampling method.

It was necessary to follow some steps to contact informants. Firstly, legal supportive letters were obtained from Woldia University research and development office. The District administrators and health and agricultural officials in Gubalafto discussed with the researcher about the objectives of the study. Consequently, they permitted and gave a collaborative letter to conduct the study in the selected kebeles. Thirdly, they sent a letter of research permit for the kebele chairpersons and the personnel of health offices. Accordingly, the lists of officially recognized traditional healers of each kebele were given along with the diseases treated by the kebele health officers. Likewise, group discussions were performed with the people about the importance of the study. Finally, the kebele chairpersons and health officers conveyed messages for the people concerning their participation in the study. Field guides were used to contact healers and collect medicinal plant specimens.

Data collection tools and procedures

Ethnobotanical data were collected from February 2013 to January 2015 in both rainy and dry seasons with a descriptive field survey design in which both qualitative and quantitative data were collected through semi-structured interviews, guided field walks, demonstrations, and focus group discussions. The semi-structure interviews were delivered with the help of pre-prepared questions in the English language. The items of the interview were done on the demographic characteristics of the informants included gender, age, job, educational level, religion, and category (either healers or general informants). Data were also focused on the uses of medicinal plants which incorporated local names, diseases treated, parts used, preparation methods, administration route/s, dosage, habits, and the habitats. The medicinal plant’s conservation practices, adverse effects (if any), taboos (if any), additional uses as wild food and livestock medicines (if any), and indigenous knowledge transfer systems were also included. Individual interviews were also conducted with each key informant for preference ranking exercise following methods used by previous researchers [14,15,16].

Data were also collected through demonstrations (plant interviews) in the cases of some females and aged male informants in their homes with the help of prior collected plant specimens collected from the field. This is because female and aged male informants had a minimal chance to move to far places to show medicinal plant specimens and their practices. Other informants also showed their medicinal plant practices in their homes and in the fields. One up to two focus group discussions were conducted in each sampled kebele with governmental officials, key informants, and other people with the help of general interview questions. Guided field walks were conducted with interviewed informants and other local indigenous people to search for additional medicinal plants in the wild and to collect medicinal plant voucher specimens. All interviewees were asked in the Amharic language, which is the language of the inhabitants of the study area, and the collected data were translated into English with the help of experts. Contact time and place were selected based on the interest of the informants.

The information about traditional medicinal plant specimens, consequently, was recorded in the notebook, and the plants were pressed with plant press and dried properly. The scientific names of the dried traditional medicinal plant specimen were identified in the National Herbarium (ETH) in Addis Ababa University, Ethiopia, by using published volumes of the Flora of Ethiopia and Eritrea [17,18,19,20,21,22,23,24,25], by the help of deposited authenticated specimens and taxonomists. Finally, the voucher specimens were deposited in ETH.

Data analysis

Data were organized and analyzed by Microsoft Office Excel spreadsheet 2007 and Statistical Package for Social Science (SPSS) version 20. Independent sample t test was computed to identify the number of medicinal plant species and associated uses reported by healers and general informants. Similarly, it was also used to identify the indigenous knowledge variation of males and females on the numbers of medicinal plant species and associated uses they mentioned. The ages of the informants were grouped into 20–39 (younger informants) and 40–84 (elder informants). Therefore, the variation in the numbers of medicinal plant species and associated uses reported within the two age groups were computed with independent sample t test.

Diseases recorded in this study were grouped into ten major categories with the help of physicians, and informant consensus factor (ICF) was calculated to determine the effectiveness of medicinal plants in each ailment category according to Heinrich et al. [26]. It was calculated by the formula: ICF = Nur − Nt/Nur − 1, where Nur refers to the number of use reports for a particular ailment category and Nt refers to the number of medicinal plant species used for a particular ailment category by all informants.

On the other hand, use value was also calculated to see the relative importance of each traditional medicinal plant species for treating diseases in the study area according to Phillips et al. [27]. It was calculated by the formula UV = ΣUi/n where UV stands for the total use value of the traditional medicinal plant species, whereas U refers to the number of use reports cited by each informant for a given plant species and n stands the total number of informants interviewed for a given plant species.

Fidelity level (FL) was computed to determine the FL values of the most frequently used plant species for treating a particular ailment according to Friedman et al. [28]. It was calculated by the formula FL = Np/N where Np stands for the number of use reports cited for a given species for a particular ailment and N refers to the total number of use reports cited for any given traditional medicinal plant species.

Furthermore, the preference ranking was determined by purposively drawn ten experienced key informants to prioritize the nine traditional medicinal plant species used for preventing bleeding according to Cotton [15]. Bleeding was preferred for ranking because it is a fatal and an emerging disease in the society.

Results

Respondents’ indigenous knowledge characteristics

Of the total 84 informants, the numbers of male participants were higher than those of females. Informants in the age range between 40 and 90 years were the highest in number (75%) and a little higher than half (53.6%) of the informants had gone through modern education (Table 1). The occupation of the informants showed that 83.3% of them were farmers, 6% were students, 3.6% were housewives, and some of the informants were represented with healers and jobless. From the total informants, 39.3% were key informants (healers) and 60.7% were general informants.

Table 1 Demographic details of the informants
Full size table

The great majority of respondents (90%) reported that most of their knowledge was received from their family members and friends secretly. The secret practices of traditional medicines came from their ancestors. However, if it is not practiced secretly, they think that the potential of the medicinal values of the plants will be diminished. Furthermore, five Muslim healers acquired their knowledge through the local graduation (MIRKAN) system from other elder traditional medicine experts. Nevertheless, elders implement this kind of graduation after having observed their activity in practice. The five Muslim healers believed that traditional knowledge shared without local graduation system could not be usable and unsuitable for treating ailments. Furthermore, 60% of the healers reported that they learned their medicinal plant knowledge from their friends in the Orthodox Church schools.

Significant differences (P < 0.05) were obtained by independent sample t test between healers and general informants on the number of medicinal plant species and associated uses (Tables 2 and 3). From the respondent’s report, it was found that some key informants were noticed with few effective remedies that treated one or two ailments like specialized doctors in modern medicines. The test did not show a significant difference (P > 0.05) between male and female informants on the number of medicinal plant species they listed and associated uses reported. However, males reported the highest number of medicinal plant species and associated uses (Tables 2 and 3). The test also confirmed that there was no significant difference on the number of medicinal plant species mentioned by the two age groups (20–39 and 40–84 years) of informants and the respective uses they explained (Tables 2 and 3). However, elders whose ages were between 40 and 84 years noticed detailed descriptions and practical preparation techniques.

Table 2 Statistical test of significance and independent t test on the number of medicinal plants mentioned by informant groups in Gubalafto District
Full size table
Table 3 Statistical test of significance and independent t test on the number of medicinal plant use mentioned by informants in Gubalafto District
Full size table

On the other hand, traditional healers and members of the society reported that traditional medicinal practices are not encouraged by the kebele governmental offices, which are considered as illegal activities. Some of the healers also reported experiencing derogatory descriptions and scoldings by calling them witchcrafts, KITEL BETASH, SIRMASH, DEBTERA and ASMATEGNA, as explained by the traditional healers, which highly reduced their interests in the traditional medicine practices freely in the society. On the contrary, some of traditional healers are not interested in having governmental legal recognition for their traditional medicine practices due to income taxes that the government levy upon them.

Moreover, 95% of the informants reported that they have not seen any documented material about the traditional medicinal plants of their area and the associated uses. They transferred the knowledge through word of mouth (orally), and through time, they lost part of indigenous knowledge due to the difficulty of memorization. Only 5% of the respondents told that their indigenous knowledge on medicinal plants has been preserved in brief notebooks.

Medicinal plant species of the study area

This study documented 135 traditional medicinal plant species belonging to 120 genera and 64 families, which are used to treat 65 human ailments (Appendix: Table 10). The plant family Asteraceae contributed the highest number of medicinal plant species (11) followed by Fabaceae, Lamiaceae, and Solanaceae with nine plant species each (Table 4 and Appendix: Table 10).

Table 4 Taxonomic diversity of medicinal plant species and their proportions
Full size table

Among the total documented medicinal plant species, Solanum incanum was used to treat the highest number of diseases (Table 5 and Appendix: Table 10). Stomachache (general abdominal problems), wound, febrile illness, swelling, and malaria were the commonly reported diseases, and these were treated with 1.6, 0.13, 0.07, 0.06, and 0.05% medicinal plant species, respectively. People in the study area give first priority for some traditional medicinal plant species to treat ailments than modern drugs. Withania somnifera, Tragia brevipes, Cucumis ficifolius and Zingiber officinale, Ziziphus spina-christi, Salvia merjamie and Salvia nilotica, and Plantago lanceolata and Ruellia patula, are found to be the most important medicinal plant species than the locally available modern drugs to treat swellings, dactylitis, stomachache, dandruff, bleeding, herpes zoster, and occurrence of baldness, respectively. Likewise, healers reported that Thalictrum rhynchocarpum, Ruta chalepensis, and Allium sativum were mixed commonly when they prepared remedy from other traditional medicinal plant species. Besides, among the documented human medicinal plant species, Carissa spinarum, Polygala sphenoptera, Cirsium englerianum, Verbascum sinaiticum, and Achyranthes aspera are also used for the treatment of livestock diseases in Gubalafto District. Likewise, Haplocarpha rueppelii, Urtica simensis, Grewia kakothamnos, Carissa spinarum, Cordia africana, Ficus vasta, and Ziziphus spina-christi are used as food for humans in the wild. The informants in Hara (hot and relatively lowland in the District) also reported that the smashed leaves of Ziziphus spina-christi have been used to prevent the human corpse from rapid deterioration and bad smell until buried.

Table 5 Individual medicinal plant species used for more number of ailments treatment
Full size table

Of the total collected medicinal plants species, most of them (83) were found from the wild, 20 were obtained from home gardens (those cultivated at home, where they are used also as food or purely for medicinal purposes or both), and 33 species were from both home gardens and wild habitats (Appendix: Table 10). The specific conservation sites for medicinal plant species were not established in the study area; however, the respondents listed the common locations namely Orthodox Church and Muslim Tomb forests, grazing lands, farm lands, riversides, governmental protected forests, and home gardens. Furthermore, the majority of the collected traditional medicinal plant species were herbs with 68 species followed by shrubs (40), trees (20), and climbers (8) (Appendix: Table 10).

Informant consensus factor

Diseases in the study area are grouped into ten ailment categories and informant consensus factor (ICF) analyses were computed. Hence, febrile illness and headache scored the highest ICF value (0.59) followed by dermal diseases (0.52) (Table 6). Febrile illness was also the top recorded health problems in Gubalafto District health office. Headache was treated with Foeniculum vulgare and Solanum incanum, whereas Carduus chamaecephalus, Conyza schimperi, Verbascum sinaiticum, Croton macrostachyus, Cynoglossum coeruleum, Eucalyptus globulus, Geranium arabicum, Lepidium sativum, and Zehneria scabra were used for the treatment of febrile illness (Appendix: Table 10). In addition, Ocimum lamiifolium was used for the treatment of both headache and febrile illness (Appendix: Table 10). Two types of remedies, which were formed from mixtures of two groups of medicinal plant species, were also reported for the treatments of febrile illness. The first group of remedy was prepared from Croton macrostachyus, Cynoglossum coeruleum, Eucalyptus globulus, Lepidium sativum, and Rumex nervosus, and the second remedy was prepared from Achyranthes aspera, Ocimum urticifolium, Bidens pilosa, and Conyza schimperi. Parts of both groups of plant species were burnt, and fumes were inhaled for the treatments of febrile illness (Appendix: Table 10). Dermal diseases had the second ICF value and the highest number of plant species used to treat it (Table 6). The least values of ICF were found in the diseases of excretory and reproductive tracts.

Table 6 Disease category and their ICF values
Full size table

Informant consensus

In addition, Ocimum lamiifolium scored the highest number of informant consensus value (30) followed by Eucalyptus globulus, Croton macrostachyus and Cynoglossum coeruleum with 28, 24, and 21 use values, respectively. A leaf of Ocimum lamiifolium is drunk with coffee/tea decoction that treated headache and febrile illness. On the other hand, Eucalyptus globulus was used to treat common cold, appetite reduction, and febrile illness. The total informant consensus values of each medicinal plant species are given in Appendix: Table 10.

Use values

The calculated results of use values (UV) showed that Ocimum lamiifolium scored the highest number, which is 0.36 and Eucalyptus globulus (0.33) scored higher use values than other species. Meanwhile, 40 medicinal plant species scored the least use value, which is 0.01 (Appendix: Table 10).

Fidelity level

The fidelity level (FL) calculation was done for the most cited medicinal plant species with six and above informants. The calculation results showed that all have more than 0.5 values (Table 7). Of the results, Rhamnus prinoides and Datura stramonium scored the highest FL values, 0.97 and 0.86 respectively.

Table 7 FL values of the 14 most referenced medicinal plants
Full size table

Preference ranking

Preference ranking values of nine medicinal plant species used to treat bleeding showed that Achyranthes aspera ranked first and followed by Rumex nepalensis (Table 8). Achyranthes aspera was reported to stop abnormal/excessive menstruation and much bleeding during the newborn delivery time. Informants stated that Rumex nepalensis stops bleeding without any patient body contact. The healers cut the leaf and soon they whispered for three times by standing at any distance from the patient by saying “stop the bleeding of the patient blood!” then drop the leaf of Rumex nepalensis to the ground. Immediately, the bleeding stops and the patient recover.

Table 8 Simple preference ranking values of nine medicinal plants used to stop bleeding in the study area
Full size table

Plant parts used and mode of remedy preparation

In the study area, eight medicinal plant parts were identified for all documented remedy preparations. Among the total plant parts, 114 traditional plant remedies were prepared from the leaves of 73 medicinal plant species. Likewise, the roots of 51 medicinal plant species were used for the preparations of 76 different remedies (Table 9). Informants applied different traditional medicinal plant remedy in different ways of preparation, of which crushing was reported frequently (Fig. 2 and Appendix: Table 10). In regard to this, most of the medicinal plant remedy preparations involved the use of single plant species or a single plant part. Thus, the mixtures of different medicinal plant species or plant parts are used rarely in the traditional medicinal plant remedy preparations. In addition, the additive substances such as salt, honey, coffee, local beer, milk, butter, and SHIRO (ground legume seeds) were mixed during traditional plant medicine preparations and administrations to extract active components, to prevent the adverse effects of remedies, and to add better tastes and aromas.

Table 9 Plant parts and their frequency of uses for the preparation of remedies in Gubalafto District
Full size table
Fig. 2
figure 2

Modes of preparation of medicinal plants in Gubalafto District. The number and percentages of preparation forms of traditional plant medicines

Full size image

Condition of preparations and storage techniques

The fresh and dried materials of traditional medicinal plant remedies were prepared by informants in the study area. The highest (132) number of remedies were prepared from fresh parts of medicinal plants only followed by a fewer number of traditional plant medicines (46) prepared from the dried plant parts only, and 64 remedies were prepared either from dry or fresh plant parts. Healers stored the collected traditional plant medicines in their homes for further usage mostly in powdered and raw dried forms. In this regard, clothes and plastic bags are used mainly to store the dried medicines. However, the preferences of fresh plant parts for medicine are higher than dried once.

Route of administration, dosage determination, and taboos

The respondent’s reports showed that most of the informants in the study area administered traditional plant medicines through oral and dermal routes (Fig. 3). Coffee cup, tine, finger line, teaspoon, tea glass, the number of powder droplets picked by two finger tips, and palm surface were used for dosage determinations. Medicines prepared from the plant species Justicia schimperiana, Podocarpus falcatus, Acokanthera schimperi, Lobelia gibberoa, Euphorbia abyssinica, Phytolacca dodecandra, and Cucumis ficifolius were reported to be toxic if overdosed. So, the informants reported that the adverse effects of toxic medicinal plant species could be alleviated by taking coffee, local beer, and flax and by eating local food like SHIRO. The healers also made different dosages of traditional medicines based on differences in gender, age, and physical condition and appearance among patients by using their experiences.

Fig. 3
figure 3

Routes of administration of traditional plant medicines. Number of traditional medicines and their administration routes reported in Gubalafto District

Full size image

Furthermore, informants in the study area reported taboos for some medicinal plant species they used. Thus, sexual intercourse was not allowed for healers during traditional medicine preparation and offering for patients. Patients are also not allowed to have sexual intercourse at the time of using Plantago lanceolata medicine to treat Herpes zoster (shingles). At the time of Tragia brevipes prescription for treating “dactylitis”, the patients are prohibited from having sexual intercourse, eating meat, and drinking milk and coffee as well as taking modern drugs. Consequently, informants provided information that the dactylitis patients preferred traditional medicines than modern medicines. Moreover, at the time of menstruation, females are not permitted to take traditional plant medicines, nor are they allowed to touch the prepared traditional medicines for use and contacting patients who took traditional medicines. Hence, patients are kept in their houses separately until they finish the prescribed traditional plant remedies. Informants mentioned about the sources and impacts of taboos that they generated from their ancestors who did these otherwise the disease cannot be cured and the chances for relapsing were said to be high.

Discussion

The most active participants in the study were males that performed their tasks out of their homes. Consequently, they could have chances to learn the useful values of plant species from their daily interactions. In addition, healers preferred males to transfer their indigenous medicinal plant knowledge because of their expectations that a male alone could take the plant species in far sites and forests. Similarly, the dominance of males in studies of traditional medicinal plants was also reported by other researchers [29,30,31,32,33,34]. In contrast, Friedman et al. [35] mentioned that women know more medicinal plants and these differences may be explained by cultural and occupational disparities. Furthermore, farming was the main task of the people in Gubalafto District that could provide for the higher number of farmers to develop indigenous knowledge on medicinal plants. Meanwhile, the secret transfer systems of indigenous medicinal plant knowledge for one or two individuals in the family members or friends orally at most could facilitate the disappearance of knowledge in the study area in the future. Hence, it should be shared for a considerable number of people in oral and written forms. The secret sharing styles of indigenous knowledge in the community are also performed in other places [2, 29, 30, 36,37,38]. On the other hand, exchanges of indigenous knowledge on medicinal plants among students in religious sites are essential for the dissemination of indigenous plant knowledge in the wider society. There are significant indigenous knowledge variations of healers and general informants showed on the number of medicinal plant species lists and associated uses they mentioned because traditional medicinal practices are the main occupations for healers in the society. In addition, the indigenous knowledge about medicinal plants from both general informants and healers is just a sequestration from generation to generation. However, the absence of significant variations between the young and elder age respondents could be that elders mostly relied on the youth for medicinal plant collections through which the younger generation got chances to know about the medicinal plant identification. This has probably helped to reduce the expected variations in indigenous knowledge on medicinal plant lists and the associated uses asked for during the study. Elders, however, gave in-depth explanations clearly about the uses of medicinal plants including that on dosages and associated histories by using their experiences than the young people.

The reason for finding a large number of documented traditional medicinal plant species and associated uses in Gubalafto District could be related to the diversity of land forms and favorable climatic conditions that the maintained varieties of plant species. Thus, the presence of different plant species in Gubalafto District could be the source of valuable indigenous knowledge used in the community. This could be related to the fact that traditional herbal medicines have helped the people to feel safe with cures indigenous to them that might also be cost-effective [1]. In addition, the preferences of the plant species like Thalictrum rhynchocarpum, Ruta chalepensis, and Allium sativum for the mixtures of remedy preparations with others indicated that these plant species could have high synergy potential because of their medicinal bioactive components. Likewise, the uses of Ziziphus spina-christi for the preservation of human corpse could be the mucilaginous substances of the smashed fresh leaves that would make the skin smooth when painted, which might reduce bacterial and fungal growths. The three documented medicinal plant species, namely, Cirsium englerianumInula confertiflora [23], and Urtica simensis [21] are found in the endemic list of plant species of Ethiopia.

Most of the medicinal plants were more available in the wild areas and have not been cultivated by households in the home gardens. Future efforts need to give due attention to conserve them around human habitations. Flatie et al. [39] reported that some of the medicinal plants were cultivated in home gardens for benefits other than medicine preparation. Hence, the medicinal plants are more exposed to extinction. Unless conserved, the medicinal plants may be highly eroded in the study area in the near future. Hence, the sustainable utilization of medicinal plant species should be practiced through awareness raising and conscious protection in situ and ex situ. In this regard, Balde et al. [34] stated that giving educational training for the people can help the management of traditional medicine easily. Similarly, various studies in Ethiopia [10, 40,41,42,43,44,45,46,47] and other countries [2, 9, 31, 33, 48, 49] reported the necessity of conservation and sustainable utilization of medicinal plant species in the society.

The record of the highest number of herbaceous medicinal plant species in the study could be attributed to the fact that their presence in most parts of the study area is due to the bimodal rainfall and extended availability of moisture in Gubalafto. Similarly, various studies in Ethiopia [29, 31, 39, 42, 44,45,46, 50] and other countries [9, 33, 51] documented the dominance of herbaceous plant species in traditional medicine preparations. In addition, Hailemariam et al. [52] stated that there were more herbaceous plant species naturally as compared to other plant habits. Works that reported dominance of woody species (shrubs and/or trees) over herbs may have been due to surveys undertaken during the dry season when most annual herbs are absent in the environment.

The presence of a higher number of plant species for traditional medicines from the family Asteraceae could be due to the adaptation potential of the species in the family in a wide range of altitudes in the study area. The evidence given for similar results from Lulekal et al. [40] revealed that the plant families that contributed to the considerably higher number of medicinal plant species were due to their wider distribution and abundance in the flora area as well as the presence of bioactive ingredients. In the same way, other ethnobotanical studies also confirmed the abundance of medicinal plant species in Asteraceae family [31, 35, 41, 49, 53, 54].

Furthermore, the ICF results of the study proved that diseases that were frequent in the study area have higher informant consensus factor (values between 0.65 and 1). In addition, the less ICF values (values between 0 and 0.65) indicated the minimal networking of indigenous people in the sharing of their knowledge on medicinal practices and this is usually the case with traditional healers. This is because of the difference in distance, altitudinal variation, and climatic conditions found among the sampled study sites in the district as well as the interest of each healer to keep his knowledge secretly from other healers for fear of piracy. The informant consensus values also indicated that the people share the knowledge of the most important medicinal plant species to treat the most frequently encountered diseases in the community. Moreover, most medicinal plant species have least use values in the study area, which could not mean that they are less effective to treat ailments. This is because the few effective medicinal plant species are reported by one or two healers. In this case, the knowledge is very secret. Likewise, the two top fidelity level value scorer medicinal plant species could be that the species found in and around home gardens which were frequently used by women to treat children diseases such as tonsillitis. In addition, more than 50% FL values of the most cited medicinal plant species suggested that there was a high level of agreement among the participants(when FL value in the arrange of 50 to 100% and less agrees when it is between 0 and 50%). Moreover, the preference ranked medicinal plant species used to stop bleeding would become therapeutic agents for emergency cases.

The greater number of traditional remedy preparations found from leaf parts of medicinal plant species had a better accessibility during field collection, ease of preparation, and effectiveness due to bioactive components in their parts. In the same way, the detailed reason for leaves as the most potential sources of traditional remedy preparation was suggested by various studies [9, 31, 32, 34, 35, 43, 44, 50, 51, 55, 56]. In addition, the uses of leaves have been supported by most investigations than roots, since using roots leads to the disappearance of the medicinal plant species forever [2, 3, 10, 30, 31, 34, 40, 46, 48, 54, 57, 58]. In the same ways, the fresh parts of medicinal plant species were the most preferred in remedy preparation due to its availability in the area at the time of necessity. In addition, the traditional medicines prepared from fresh parts of medicinal plant species helped to keep their efficacy and safety for immediate uses. On the other hand, medicinal plant remedy used in dried form could reduce its potential efficacy and safety due to the bioactive components exposed to evaporation, other chemical reactions, and decay with available moisture in storage. In this regard, other researchers also documented the preference of fresh medicine for uses [42, 44,45,46, 50, 53].

In the same vein, most of the administered remedies via oral routes indicated the higher prevalence of internal ailments in the study area. However, the dose should be given in great care in the oral system than in the dermal since it might cause other severe internal problems. Similarly, various research findings mentioned oral application as the primary route of administration in traditional plant medicines [1, 43,44,45, 50, 53, 55, 58,59,60]. Giday et al. [61] in their studies in southwest Ethiopia reported that most bench herbal remedies were applied topically on the skin. The additives mixed during remedy preparations and administrations could dilute the crude plant medicines and make it safer for the patient. Likewise, the significances of additives in the preparations of traditional plant medicines were described by other research results [30, 36, 44, 55]. The lack of standardized measuring units for traditional medicines and its drawbacks have been mentioned by many researchers [2, 30, 37, 40]. Moreover, the reports on side effects related to inappropriate dosages might reduce the traditional uses of plants for healthcare systems by the people.

Comparative review results from similar studies

All documented traditional medicinal plant species in this study were searched in the published similar research works in Ethiopia in particular and the world outside Ethiopia [1,2,3, 9, 10, 31,32,33,34,35,36, 38, 40, 42, 45,46,47,48,49,50,51, 53, 55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84]. From this review, 121 recorded medicinal plant species in this study are likely also to be found in other parts of Ethiopia and other countries. Among these, 73 of the species had similar uses with other studies and 49 had unlike functions (Appendix: Table 10 & 11) in the medical lore of Gubalafto. In addition, the medicinal plants, which have similar uses within this study, also showed different preparation and application techniques. Furthermore, 17.85 mean percentages of new uses were found from the comparative reviews (Appendix: Table 11). Hence, doing an ethnobotanical study on the traditional uses of medicinal plant species in different areas would help to document new additional uses from already known traditional medicinal plant species. On the other hand, 14 medicinal plant species documented in this study were not found in any of the related literature reviewed (Appendix: Table 10). These medicinal plants are Actiniopteris dimorpha, Aloe weloensis, Conyza schimperi, Grewia kakothamnos, Haplocarpha rueppelii, Huernia macrocarpa, Indigofera brevicalyx, Kedrostis gijef, Melilotus suaveolens, Oncocalyx schimperi, Polygala sphenoptera, Pteris dentata, Ranunculus stagnalis, and Thesium kilimandscharicum.

Conclusions

The traditional medicinal plant species are the potential sources in traditional healthcare systems of the people in Gubalafto District. The study confirmed that the people have been using medicinal plant species and the associated indigenous knowledge as a primary option although modern health services are expanding in the District. The documented new traditional medicinal plant species in this study have validated the call for further scientific research on their ethnobotany and other aspects. The study also ensured that the communities did not have turned deep insight in the conservation of the useful medicinal plant species and associated uses. The indigenous knowledge tied with medicinal plant species were found in both younger and older age groups by which the younger reduced their interest in searching, sharing, and documenting processes. Higher use value, preference ranking scores, and fidelity level values of the recorded medicinal plant species would empower the future pharmaceutical and phytochemical investigations and conservation practices. In this connection, attention should be drawn to the conservations of traditional medicinal plants and associated indigenous knowledge in the study area to sustain them in the future.