Consumption of wild edible plants in the Kofale and Heban-Arsi districts, West Arsi Zone, Oromia Regional State, Ethiopia

Abstract

Background

Wild edible plants (WEPs) are neglected and have received little attention despite their significant contributions to the sustenance and livelihoods of rural communities. This study was conducted in the Kofale and Heban-Arsi districts of the Oromia Regional State, Ethiopia, to document the diversity, to assess the most preferred WEPs, their utilization, and threats they face.

Methods

The study was conducted in the Kofale and Heban-Arsi districts of the West Arsi Zone of the Oromia Regional State, Ethiopia. Data collection took place from February to September 2022 in Kofale and from November 2022 to April 2023 in Heban-Arsi district. To gather ethnobotanical information, the research employed semi-structured interviews, field observations, focus group discussions, and guided field walks. The interviews involved 290 informants who were selected via snowball sampling and systemic random sampling methods. Preference ranking values, direct matrix rankings, and use values (UVs) of documented species were computed.

Results

A total of 62 WEPs species belonging to 38 families and 56 genera were identified. The Moraceae family includes 7 species, followed by Fabaceae and Rubiaceae (each 4 species), and Lamiaceae (3 species). Shrub was the dominant growth form (32 species), followed by herbs (13 species). The largest number (24 species) of WEPs was collected from grazing lands/fields, followed by forest habitats (17 species). The most widely used edible plant part was fruit (40 species) and leaf (11 species). Most WEPs were collected for consumption from March to May (30 species), and the majority of the species (48, 77.4%) were utilized in their raw state. A large number of WEP (41 species) were consumed only during periods of food shortage, and the remaining (21 species) were used as staple food supplements. Multiple other uses of WEPs in the study area also reported. Fifty-two species mentioned for medicinal use, and the species that had the highest use value was Cordia africana Lam. (0.9). The direct matrix ranking results indicated that agricultural expansion was a principal threat to the WEPs in the study area.

Conclusion

This study indicated that WEPs are widely used during food shortages in the study area, but many WEP species are under threat due to growing pressure from various anthropogenic factors. Thus, public awareness and community-based management need to be encouraged at all levels to conserve and sustainably use these resources to address food insecurity.

Background

For generations, the majority of rural communities have used wild edible plants (WEPs) for food, medicine, and other purposes [1]. According to the Food and Agriculture Organization (FAO), WEPs are defined as non-cultivated and non-domesticated plants [2]. In recent years, interest in the use of WEP resources has increased [3]. This might be due to the rising concern of global hunger attributable to the increasing human population and urban development [4, 5]. On the other hand, the replacement of traditional food products with imported or newly introduced foods, particularly those high in refined and processed ingredients, fats, and sugars, may lead to nutrient deficiencies and an increase in diet-related non-communicable diseases such as obesity, type 2 diabetes, and cardiovascular conditions [6]. Wild but naturally growing vegetables and fruits considered healthier than cultivated vegetables because they are free of chemicals, such as residues from fertilizers, herbicides, and pesticides [7].

Malnutrition remains a persistent public health issue in sub-Saharan Africa, impacting health, mental well-being, productivity, and economic progress [8, 9]. Thirty-eight percent (38%) of Ethiopian children less than 5 years of age suffer from chronic malnutrition, and 22% of women of reproductive age are undernourished [10]. Several studies have suggested that the nutritional composition of WEPs is greater than that of agricultural crops [11]. They provide valuable nutritional supplements (nutraceuticals), including trace elements, vitamins, polyphenols, antioxidants, and flavonoids, and have very low lipid levels [12, 13]. Moreover, the utilization of WEPs enhances socioecological resilience for the sustainable development of communities [2]. Therefore, integrating WEPs into the mainstream food system through scientific safety assessments, raising community awareness about their benefits, and supporting their conservation and cultivation could be crucial in tackling widespread malnutrition and food insecurity and this approach would contribute significantly to achieving the United Nations' sustainable development goal of ending hunger [14].

Several studies [15,16,17] have highlighted the importance of WEPs in Africa, especially during famine or food shortages. In areas where food insecurity is prevalent during food shortages [18], most rural Ethiopian populations rely on WEP resources [11]. It was reported that WEPs have the potential to bridge food and nutritional deficits in food insecure households in Turkana County, Kenya [15]. Another study [16] reported that WEPs are an important source of nutrients and income for poor households and hence reduce vulnerability to food insecurity in rural areas of Tanzania [16]. A similar study also indicated that many people in rural communities of Nigeria rely on wild edible plants for food, especially during crop failures, famine or periods just before new crop harvests [17].

Ethiopia is endowed with approximately 6000 plus plant taxa because of its diverse agro-ecologies that favor high biodiversity [19]. Of these, 413 are WEPs [20]. However, there are many undocumented WEPs in the country. Recently, several ethnobotanical studies have been conducted in Ethiopia, primarily on medicinal plants [21]. Little emphasis has been given to WEPs, although these species address seasonal food shortages and nutritional gaps in the country [21]. Wide ranges of WEPs are used by local communities in rural areas of Ethiopia for food, medicine, and spices, as well as for cultural and ritual purposes [22]. However, the WEPs in Ethiopia are threatened by deforestation and habitat deterioration through agricultural expansion [22, 23]. In the current study area, especially the lowlands of the Heban-Arsi district, where environmental degradation, drought, and famine frequently affect the indigenous community, the consumption of WEPs seems to be an important local survival strategy. Therefore, investigating wild food plants available in the area might help to improve the present situation of food shortages and for future preservation and sustainable use of these resources. To the best of our knowledge, no previous study has been conducted on the use and diversity of WEPs in the current study districts. Thus, the main aims of this ethnobotanical study were to (1) identify and document the wild edible plants used in the Kofale and Heban-Arsi districts and (2) assess the most preferred and widely used WEPs in the Kofale and Heban-Arsi districts, which may serve as a basis for future conservation and nutritional analysis This study is expected to contribute to future generations' understanding of the potential of wild edible plants (WEPs) as alternative and sustainable food sources, particularly in combating hunger and malnutrition during periods of food insecurity.

Materials and methods

Description of the study area

The study was conducted in the Kofale and Heban-Arsi districts, West Arsi Zone, Oromia Regional State, and southeastern Ethiopia. Kofale district is geographically located between 6° 50′–7° 9′ N and 38° 38′–39° 4′ E, south of the capital Addis Ababa, with an elevation ranging from 1500 to 3000 m.a.s.l. (Kofale District Health Care Office (KDHCO), unpublished data), and the Heban-Arsi district is located at 7° 9′–7° 42′ N and 38° 25′–38° 54′ E, with an elevation ranging from 1250 to 2500 m.a.s.l. (Heban-Arsi District Agricultural Development Office (HADADO; unpublished data)) (Figs. 1, 2).

Fig. 1

Map of Kofale District, West Arsi Zone, Oromia Regional State, Ethiopia

Fig. 2

Map of Heban-Arsi district with the sampled kebeles highlighted

Study sites and informant selection

Before conducting the actual data collection, study sites and informants were selected based on information gathered during reconnaissance survey from the administrative, agricultural, and natural resource management offices of the study districts by adopting a method previously used in a similar study [24]. Study kebeles (the lowest administrative structures in Ethiopia) in the two districts were selected based on agro-ecological variations, history of use, and the availability of WEP in the area. Accordingly, eight kebeles, namely Wege Abosa, Benjo Ashoka, Ilka Bebe, Sayimana Mudi, Chatimana Jangala, Guchi, Bulchana, and Garmama, from the Kofale district and four kebeles, namely Argada Shaldo, Sanbaro Rogicha, Buku walda, and Dawe, from the Heban-Arsi district were selected. The data were collected in parallel to a previously reported ethnobotanical study of medicinal plants in the same districts [25]. Accordingly, the data were collected by interviewing 290 informants. Among these, 104 were key informants who were selected using the snowball sampling method [26], 84 from the Kofale district and 20 from the Heban-Arsi district (Table 1). According to this study, key informants are individuals who possess a higher level of awareness about WEPs and the regional conditions in the study area compared to other residents and are more knowledgeable than general informants. The remaining 186 informants (115 from Kofale district and 71 from Heban-Arsi district) were general informants who were selected by systemic random sampling methods.

Table 1 Sampled administrative kebeles their position, elevation, no. of households and sociodemographic profiles of interviewed informants

Data collection

Ethnobotanical data of WEPs were collected between February and September 2022 and November 2022 and April 2023 from the Kofale and Heban-Arsi districts, respectively. The methods and protocols proposed by Martin [27] were used to collect ethnobotanical data on the WEPs. Before conducting the interviews with key and general informants, a meeting was organized with the help of local administrators to discuss the objectives of the study and its importance for communities. Following consensus reached between researchers and informants on the objectives and importance of the study, oral consent was obtained from all participants. Ethnobotanical information about wild edible plants, including edible parts, growth habits, habitats, harvesting season, mode/form of consumption as food (fresh or processed) and other uses, was collected through semi-structured interviews, field observations, focus group discussions (FGDs), and guided field walks. Twelve FGDs, one in each kebele involving 5 to 6 participants, were organized and discussed on information focusing on the status and use of wild edible plants, plant species and their use, the degree of dependence on WEPs for livelihood during prolonged drought and famine, threats to wild edible plants, and conservation status [28]. In addition, information on sociodemographic characteristics of the informants (age, gender, and education level) was also gathered [26].

The semi-structured interview questions were initially prepared in English and translated into Afan Oromo, the frequently spoken language in the area, and responses were translated back to English during documentation. The International Society of Ethnobiology Code of Ethics was taken into account in the interviews [29]. Plant samples were collected pressed, dried, and recorded by their vernacular names along with a voucher number, and specimens were identified at the National Herbarium (ETH) by using published volumes of the Flora of Ethiopia and Eritrea [27, 30, 31] and comparison with authentic specimens, taxonomic keys, and with the assistance of experts at the National Herbarium (ETH), AAU [32], and deposited at the mini-herbarium of the Aklilu Lemma Institute of Pathology and the National Herbarium of Addis Ababa University, Addis Ababa, Ethiopia.

Data analysis

The collected data were organized using Microsoft Excel spreadsheet 2016. Descriptive statistical methods were used to analyze and summarize the data using the Statistical Package for Social Sciences (SPSS) version 25. Comparisons of the WEPs knowledge of various sociodemographic groups based on their age and educational status were made using one-way analysis of variance (ANOVA), and differences in means with p values ≤ 0.05 were considered to indicate statistical significance. Comparisons of wild edible plant knowledge between male and female informants were made using a two-tailed independent sample t-test. Preference ranking and direct matrix ranking were applied to assess the degree of preference of selected WEPs and threats to them, respectively [27], and the use priority of WEPs, respectively. The general WEP use values were calculated using all uses mentioned by informants for each cited species using an adapted formula [33], as used in [28].

Ethical considerations

The study proposal was reviewed and approved by the Addis Ababa University, Aklilu Lemma Institute of Pathobiology Institutional Research Ethics Committee (ALIPB-IRERC). Permissions were obtained from the study districts and Kebele administrators to carry out the fieldwork. Participants in this research were informed about the objectives and importance of this study. Oral consent was obtained before the interview. The ethical guidelines adopted by the International Society of Ethnobiology were followed during data collection.

Results

Demographic characteristics of the informants

In this ethnobotanical study, 290 local inhabitants from two districts were interviewed to obtain information on diversity of wild edible plants used, parts of plants consumed, seasonal availability, use forms (fresh, dry and/or processed), and their threats. The respondents’ sociodemographic data were also gathered (Table 2). The participant’s age ranged from 18 to 89 years, with the majority (145; 50%) falling between 41 and 60 years of age. Most of the informants were males (263, 90.6%), whereas 27 (9.3%) of them were females. Among the informants, 153 (52.9%) were illiterate (cannot read and write), and 137 (47.2%) were literate. Among the literate participants, 97 (71%) completed primary education, while 40 (29%) had completed secondary and higher education. Comparison of WEPs knowledge between male and female informants using a two-tailed independent sample t-test revealed that there was a significant difference in knowledge between them (p < 0.05) (Table 2). There was also a significant difference in WEPs knowledge among the two informants’ age groups (p < 0.05); older people knew more WEPs than the young people did (Table 2). From an educational status perspective, a significant difference in WEPs knowledge (p < 0.05) between literate and illiterate informants was observed, and the findings showed that illiterate respondents held more knowledge than by literate respondents.

Table 2 Demographic categories of local respondents and mean number of reported wild edible plants by the different social groups

Diversity of WEPs, their growth forms, and habitats

A total of 62 WEP species belonging to 38 families and 56 genera were documented to be used as food sources during times of food shortage in the two study districts, such as prolonged drought and famine, and as dietary supplements. The family Moraceae was represented by 7 species and was followed by Fabaceae and Rubiaceae (each 4 species) and Lamiaceae (3 species). The families Amaranthaceae, Boraginaceae, Polygonaceae, Rhamnaceae, and Apocynaceae were represented each by two species, while the remaining families were represented by a single species each. Table 3 provides the details of the utilized WEP species arranged in alphabetical order, including their scientific name, family name, voucher specimen number, local name, growth form, parts used, collection sites, and uses. Analysis revealed that 56 WEPs were consumed in Heban-Arsi district, while 39 were consumed in Kofale district. Of the total reported WEPs, 34 species were shared by the two study districts.

Table 3 List of WEPs including their local names, families, growth habits, edible parts, modes of consumption, additional uses and habitats

Growth form analysis of WEPs reported in the study area revealed that shrubs constituted the largest category (32 species, 51.6%), followed by herbs (13 species, 21%) and trees (12 species, 19.35%) (Fig. 3).

Fig. 3

Growth forms of wild edible plants

The people in the Kofale and Heban-Arsi districts collected wild edible plants from various habitats, including grazing lands/fields (24 species), forest habitats (17 species), riversides (2 species), farm margins (2 species), roadsides (2 species), and woodlands (2 species) (Table 4).

Table 4 Habitats of wild edible plants in the study area

Parts consumed and time of gathering

Of the total documented edible parts, fruit was the most frequently consumed plant part, representing 38 (63%) species. Leaves occupied the second position, accounting for 11 (17.74%). Some plants have different/alternative edible parts, such as leaves and seeds (Amaranthus dubius Mart. ex Thell.) fruits and shoots (Rumex nervosus Vahl), and stems and fruits (Phoenix reclinata Jacq.) (Fig. 4).

Fig. 4

Edible parts of the reported wild edible plants

The study indicated that the harvesting periods of plants depend on the seasonal availability of the edible parts of WEPs in the districts. The majority of the WEPs in the study districts were harvested from March to May (48%), June to August (17.74%), and September to November (14.6%).

Mode of consumption

The majority of the species 48 (77.4%) were harvested and utilized in their unprocessed form. Fourteen (14%) of the species were consumed after chopping with a knife and cooking, while others were subjected to methods such as roasting, powdering, and boiling. Fruits are largely collected and consumed by the community when they were ripened. The ripening stages of fruits are mainly indicated by changes in color of fruits for a wide variety of edible plants. Leafy vegetables, on the other hand, were reported to be consumed during their early developmental stage (very green stage). In the current research districts, WEPs were utilized during periods of food scarcity, such as prolonged drought and famine, as well as during normal periods. A significant portion of the WEPs (41 species, 66%) were exclusively consumed during periods of famine or food shortages, while 21 (34%) were used to supplement staple foods.

Preference ranking of selected wild edible plants

Eight key informants were selected to rank eight commonly utilized WEPs based on their sweetness qualities and their safety. Based on the degree of preference by informants, the plants were assigned values ranging from 1 to 5, with the highest rank, 5, attributed to the most favored plant and the lowest rank, 1, assigned to the least favored plant. Consequently, Syzygium guineense (Wild.) DC and Ficus sycomorus L. took the top two ranks, 1st and 2nd, respectively, followed with Allophylus abyssinicus (Hochst.) Radlk, Ximenia americana L., Grewia ferruginea Hochst. ex A. Rich and Carissa spinarum L. (Table 4).

Direct matrix ranking

In addition to serving as a source of sustenance, indigenous populations have utilized WEPs for a wide range of purposes, such as firewood, fence building, house construction, medicine, farm tools, furniture, and cultural uses. The cumulative utilization values for eight plant species reported to have diverse uses were computed based on direct matrix ranking. The findings indicated that the use values for medicinal purposes, fuel wood, construction of fences, and provision of fodder ranked first to fourth, respectively (Table 5). The finding of the direct matrix ranking exercise showed that Cordia africana Lam. was the top-ranked WEP for its diverse uses in the study areas, followed by Syzygium guineense (Willd.) DC. and Vachellia seyal (Delile) P.J.H.Hurter (Table 5).

Table 5 Ranking of eight selected WEPs according to informant preferences

Use values (UVs)

The use values (UVs) for each species were calculated to determine their relative importance to the local people. The five species with the highest UVs were Cordia africana Lam. (0.9), Syzygium guineense (Willd.) DC. (0.8), Vachellia seyal (Delile) P.J.H.Hurter (0.74), and Euclea racemosa subsp. schimperi (A.DC.) F.White (0.6), Allophylus abyssinicus (Hochst.) Radlk. (0.3) (Table 6). The species with the lowest UVs were Vachellia etbaica (Schweinf.) Kyal. & Boatwr. (0.06), Grewia ferruginea Hochst. ex A. Rich. (0.03), Dombeya torrida (J.F. Gmal.) P. Bamps (0.02), and Rumex nervosus Vahl (0.01) (Table 6).

Table 6 Direct matrix ranking of eight wild edible plant species against ten use criteria (5 = best; 4 = very good; 3 = good; 2 = less used; 1 = least used and 0 = no value)

Threats to wild edible plants in the districts

The few remaining forests in the study districts with significant populations of WEPs are facing persistent deforestation by the local population. The primary drivers for the decline in WEPs within the area included the expansion of agricultural land, the collection of fuel wood, unsustainable practices, the impacts of climate change, and the introduction of non-native plant species. Among these factors, the expansion of agricultural land identified as the most prominent, followed by fuel wood collection, as shown in Table 7.

Table 7 Priority ranking of threats against the WEP in the study districts

Discussion

The findings of the present investigation revealed the widespread use of WEPs in times of food scarcity as well as food supplementation in the Heban-Arsi and Kofale districts, Oromia Regional State, Ethiopia, as evidenced by the extensive diversity of WEP species documented (Table 3). The Moraceae family was represented by 7 species and was followed by Fabaceae (4 species), Rubiaceae (4 species), and Lamiaceae (3 species). Previous studies on WEPs also reported a greater abundance of plant species from the Moraceae family with 6 and 11 species documented in the study conducted by [37, 60], respectively, in Ethiopia. On contrary, some earlier studies in other parts of Ethiopia showed that the Fabaceae family was reported to be dominant families in Ensaro district, Amhara regional state, Ethiopia, with 4 species [38, 48, 56] reporting highest contribution of Rubiaceae family (5 species) in Dibatie district, Metekel zone, Benishangul Gumuz Regional State, western Ethiopia. Other study [61] reported the Lamiaceae as dominant family in Tiyo district, Arsi Zone, Oromia, Ethiopia. The distribution of these families could attribute to their wider growth throughout various agro-ecological zones all over the country [59]. At the genus taxonomic level, the genera Ficus and Grewia (3 species each) contributed the highest number of species in study areas. Grewia was also reported as abundant wild food contributing genera (3 species) elsewhere in Ethiopia [28].

The Moraceae family often called the mulberry family is flowering plants comprising about 40 genera and over 1,000 species. Most are widespread in tropical and subtropical regions [62]. The Fabaceae family encompasses over 20 genera and its members are adaptable to a range of environments and are economically significant [63]. The food crops within this family provide high levels of protein and essential micronutrients, which are crucial for improving livelihoods and health [63]. Particularly in developing countries, the therapeutic benefits of the Fabaceae family are well recognized [64].

In general, 62 species of WEPs were identified in the surveyed districts and were higher compared to the numbers reported in other regions of the country: 41 species [28], 38 species [65], and 54 species [56]. However, the number of WEPs reported by the current study was lower than those reported by previous studies by different researchers, respectively, reporting 71 [66], 64 [50], and 66 [11] WEPs in Ethiopia. This disparity in the number of reported wild edible plants could be due to differences in culture, vegetation cover of the area, or climatic variation and the existence of different agro-ecological zones in the study districts [59, 67].

In comparison with previous ethnobotanical studies, most of the edible plants identified in this study have also been reported as edible in other regions of Ethiopia. For example, 24 species were documented in the study conducted in Arsi Robe district of East Arsi Zone, Ethiopia [46], 22 species in Dibatie district, Metekel zone, Benishangul Gumuz Regional State, western Ethiopia [56], 21 species in pastoral and agro-pastoral communities of Mieso district, eastern Ethiopia [28], and 20 species were documented in Midakegn district, West Shewa Zone, Central Ethiopia [59]. In addition, the studies conducted by [60] in the Awi Agäw community, northwestern Ethiopia (17 species), [68] in the Sedie Muja District, South Gondar Zone, northwestern Ethiopia (15 species), [69] in the Berek Natural Forest, Oromia Special Zone, Ethiopia (14 species), and [70] in the East Hararghe Zone, Oromia, Ethiopia (11 species), all showed overlaps of WEPs with the current study. The similarity in the distribution of WEPs and their traditional uses may be attributed to the geographical proximity and cultural exchange among local communities residing in these different regions [56].

Out of the 62 recorded WEPs in the study area, 4 species, such as Galiniera saxifraga Hochst. Bridson, Ficus ruspolii Warb. Ranunculus multifidus Forssk, and Myrsine melanophloeos (L.) R.Br. ex Sweet were not reported in the previous studies conducted in different parts of Ethiopia, as well as in 413 WEPs reviewed by [20]. On the other hand, some WEPs, such as Balanites aegyptiaca (L.) Delile, Ficus sycomorus L. Carissa spinarum L, Syzygium guineense (Willd.) DC, and Ximenia americana L., were highly reported by the previous studies and widely consumed in many areas of the country [28, 56, 59].

Comparative analysis of the two studied districts revealed that the greatest diversity of WEPs (56 species) was collected from the Heban-Arsi district and 39 species from the Kofale district. More WEPs consumed in the Heban-Arsi district than in the Kofale districts, which might be due to the availability of large areas of grazing land/fields. More species were collected from lowland and midland areas of Heban-Arsi district (between altitudinal range of 1250 and 2000 m a.s.l.). A high abundance of WEPs in such agro-ecological zones was also reported elsewhere [11] in Ethiopia. Thirty-four species shared between the communities in the two districts. The similarity in wild edible species between the Heban-Arsi and Kofale communities might be attributable to the overlap of their ecological niches, cultures, and languages. Similar observations also reported elsewhere by several researchers [26, 71].

Shrub was the dominant growth form of WEPs in the study districts (32 species, 51.6%), followed by herbs (13 species, 21%). The dominance of wild edible shrubs and herbs might demonstrate the better availability of WEPs for harvesting throughout the year [56]. Similarly, the wide utilization of shrubs also reported in other parts of Ethiopia [42, 72,73,74]. The predominant (12%) use of shrub growth form also reported in Sampang and Pamekasan districts of Indonesia [74]. In contrast, trees were reported as the main sources of wild food in different parts of Ethiopia such as in Dibatie district, Metekel zone, Benishangul Gumuz Regional State, western Ethiopia 38 species [56], and in Soro district, southern Ethiopia 22 species [50].

The habitat distribution of the surveyed WEPs covered a diverse ecological range from low to high land (1350–2736 m, a.s.l). The greatest number of WEPs (24 species, 38.7%) was collected from grazing lands/fields, followed by forest habitats (17 species, 27.4%). A similar study conducted by [11] in Ethiopia also found that 62.1% of the wild edible plant species were gathered from wild fields, which supports the findings of our study.

In the current study districts, Fruits were the predominant component of the WEPs consumed 38 (63%) species, followed by Leaves 11 (17.74%) species. In line with the current findings, the dominance of fruit use was also mentioned in other studies in Ethiopia [28, 57]. The studies on (WEPs) in communities near Mabira Central Forest Reserve, Uganda [75], and in Nepal [26], also reported the predominant of 66% and 54.3% fruit plants part used for consumption, respectively. The preference for consuming whole fruits may be due to their convenience, minimal processing, high nutritional benefits, and superior taste and sweetness [11]. Similarly, the fruit parts of WEPs have high nutritional value and secondary metabolites compared to those of cultivated crops [11].

Wild edible leaves are frequently consumed, after fruits, during the summer months when food shortages occur in the study areas. Studies showed that wild edible leaves are a suitable nutrient supplement to a carbohydrate-rich diet of poor rural communities [76]. WEPs leaves are particularly rich in protein, calcium, iron, vitamins and are antioxidants [77] and many are also known for their medicinal properties [14]. Some WEPs have different/alternative edible parts, such as leaves and seeds (Amaranthus dubius Mart. ex Thell.), fruits and shoots (Rumex nervosus Vahl), and stems and fruits (Phoenix reclinata Jacq). The ability of wild edible plants to offer multiple edible parts may enhance their utility and value, supporting diverse dietary needs [78].

Temporal variability in the growth of WEPs species affects their availability [79]. WEPs were collected and consumed in different seasons of the year. The present findings revealed that WEPs collected mainly in the months of March, April, and May. Some WEPs also collected in October, November, and December. The months of March, April, and May were also reported as the major harvesting periods in Mieso district, eastern Ethiopia [28]. The main WEPs collected from March to May were Balanites aegyptiaca (L.) Delile, Carissa spinarum L., Capparis tomentosa Lam., Allophylus abyssinicus (Hochst.) Radlk, and Ficus vasta Forssk.

Food scarcity frequently observed in lowlands and some midland areas of the Heban-Arsi district from June to August. During this period, the majority of rural communities use WEPs as basic sources of food until cultivated agricultural crops mature. A similar report on the use of WEPs during food shortages and famine mentioned in another study in Ethiopia [11, 24]. The use of WEPs during food shortages and famine was also reported in Boumba, Niger [80], and in Bangladesh [81].

The majority of the WEPs 48 (77.4%) in the study districts harvested and utilized in their unprocessed form. Fourteen (14%) of the species were consumed after chopping with a knife and cooking, or roasting, powdering and boiling. A significant portion of the WEPs (41 species, 66%) were exclusively consumed during periods of famine or food shortages, while (21 species, 34%) were used to supplement staple foods. Plants such as Allophylus abyssinicus (Hochst.) Radlk, Balanites aegyptiaca (L.) Delile, Carissa spinarum L., Capparis tomentosa Lam., consumed regularly as supplementary food during their ripening seasons. Conversely, plants such as Vachellia etbaica (Schweinf.) Kyal. & Boatwr, Euclea racemosa subsp. schimperi (A.DC.) F.White, Gallium sp., and Asparagus africanus Lam. were among the wild edible plants consumed specifically during times of food shortage in the study districts. Consumption of raw WEPs have also been observed in various regions of Ethiopia such as in Derashe and Kucha Districts, South Ethiopia [11], in Midakegn District, West Shewa Zone, Central Ethiopia [59], in Nhema communal area midlands province, Zimbabwe [82], and around selected forest reserves of Teso-Karamoja region, Uganda [83].

In preference ranking of WEPs, factors such as taste, availability, accessibility, cultural acceptability, its further needs for pharmacological and nutritional studies, and conservation needs determines the preference of one edible plant over another [82]. In this study, preference ranking exercise conducted on the most commonly used WEPs based on their sweetness and safety. The perceived safety of WEPs according to informants was determined based on the absence of stomachache, bloat, and vomiting after consumption. The findings of the preference ranking exercise indicated that Syzygium guineense, Ficus sycomorus, Allophylus abyssinicus, Ximenia americana, and Grewia ferruginea were ranked from 1 to 5, respectively. The results of the preference ranking exercise showed that informants agreed on the importance of these WEPs, highlighting the need for further research into their nutritional, pharmacological, and safety aspects to support their sustainable use through cultivation and propagation {24].

Ficus sycomorus is an excellent source of iron and a good source of calcium and magnesium [84]. Previous evaluation of methanol crude extracts of Ficus sycomorus suggest that the fruit extracts have significant amounts of total phenolic and flavonoid compounds with potential cytotoxic and antimicrobial activities [85]. The nutritional and medicinal contribution of wild fruit of Ficus sycomorus also reported in Ethiopia by [86]. The presence of essential amino acids such as histidine, isoleucine, lysine, methionine, phenylalanine, and tryptophan in Syzygium guineense fruits was reported by [87] in South Africa. Studies in Ethiopia showed that Syzygium guineense fruits and seeds are valuable sources of bioactive compounds such as phenolic acids, flavonoids and anthocyanins and have strong antioxidant activities [24]. Study by [88] in Brazil showed that the seed of Ximenia americana has strong antioxidant activity which could be attributed to polyphenol and vitamin C contents.

The sustainable use of WEPs is crucial for the environment, food security, and medicine, as these plants are climate-resilient, help address food insecurity and malnutrition, and contribute to improve health [89]. Consequently, WEPs contributes to an improved quality of life and environmental sustainability [90]. These plants are well adapted to their environments and climate fluctuations, contributing to ecosystem resilience in the face of changing climates (7). They support biodiversity by providing essential ecosystem services, such as maintaining soil health, improving water retention, and offering habitats for wildlife (24). Their resilience makes WEPs particularly valuable for farmers in developing countries, as they are better equipped to withstand extreme climate events compared to conventional crops (27). Consequently, the genetic resources of these plants are vital for ensuring long-term food security and sustainability [28].

WEPs offer significant nutritional benefits compared to imported foods, which often contain refined ingredients and sugars that can lead to nutrient deficiencies and diet-related diseases. Unlike these foods, wild vegetables and fruits are typically free from harmful chemicals such as fertilizers, pesticides, and herbicides (7). WEPs are especially important in regions where conventional food sources are scarce or unreliable, providing vital nutrition during times of food shortages or crop failures and helping to mitigate food insecurity (70). Studies show that WEPs are rich in protein, carbohydrates, minerals, and vitamins, particularly B vitamins, which are essential for nutrition, food security, and health (80). Furthermore, these plants are integral to local food traditions and cultural practices, supporting food sovereignty by preserving traditional knowledge and enabling communities to manage their own food resources, thereby fostering self-reliance and reducing dependence on external food systems (69).

The finding of the direct matrix ranking exercise showed that Cordia africana was the top-ranked WEP for its diverse uses in the study area, followed by Syzygium guineense and Vachellia seyal. The greater use value of Cordia africana in the districts was related to its multiple uses, such as medicine, construction, fuel, fence, house furniture, cultural value, shade, gum, spiritual, bee hive, fodder, soil holding, water accumulation/holding during drought and ecological significance. The multipurpose uses of Cordia africana were also reported in Chelia district, West-Central Ethiopia [44], and in Bule Hora Woreda, southern Ethiopia [47]. Panda [91] also reported the multiple uses of WEPs for different uses.

In our study, the primary uses of wild edible plants (WEPs) were identified as medicinal purposes, firewood collection, and fencing, with medicinal use being the most common, followed by firewood collection and fencing (Table 3). A significant majority (83.8%) of WEPs were reported for medicinal applications, addressing a wide range of health issues, including diabetes, liver diseases, cancers, skin disorders, and malaria, diarrhea, and stomach aches [25]. Many of these plants serve dual purposes as both food and medicine, which is a well-established feature of traditional medicinal systems [92]. For example, Syzygium guineense fruit is used as food during food shortages, while its leaves are used to treat diarrhea and hypertension [25]. Similarly, Ximenia americana fruit is consumed as food, while its leaves are used in traditional remedies for wounds, diarrhea, leprosy, fever, headaches, ulcers, and skin problems [41].

In the study area, it was reported that the bark part of Maesa lanceolata Forssk was crushed and boiled and topically applied for the treatment of dermatophilosis. However, its leaves were boiled and drunk for the treatment of diabetes [25]. The ripen fruit of Galiniera saxifraga consumed as wild food by cattle herders in the area. However, its fruit decoction is used for the treatment of malaria and anthrax, and its bark is crushed and boiled and drunk for the treatment tuberculosis in the area [25]. The fruit of Dombeya torrida (J.F. Gmal.) P.Bamps is consumed during food scarcity in the study area. However, its leaves are squeezed and mixed with water and drunk with tea cup to treat snake poison in the Heban-Arsi district. Dried fruits of Capparis tomentosa powdered and the decoction is drunk to enhance male erectile problem in the Heban-Arsi district, while its ripen fruit consumed by cattle herders during the spring season.

In some WEPs, similar parts are used for both food and medicinal purposes. The ability of certain WEPs to serve dual functions enhances their importance by providing nutritional and medicinal benefits, and utilizing the same plant parts for multiple purposes promotes sustainable use of resources. It reduces the need to cultivate separate plants for food and medicine, thereby conserving space, water, and other resources [93, 94].

WEPs play a vital role in supporting the survival and livelihoods of many rural communities, particularly pastoralists, due to their accessibility, local knowledge, and affordability [10]. These plants are especially important for marginalized groups, such as women and children, who are more vulnerable to climate-related shocks like drought [10]. WEPs improve food security by providing nutrition during times of scarcity and famine, and they also contribute to income and have cultural and spiritual significance [12]. For instance, fruits, vegetables, and seeds from WEPs are rich in essential nutrients, addressing nutritional deficiencies in vulnerable populations [13].

WEPs are under threat due to land use changes, climate change, overexploitation, and urbanization, which are decreasing the availability of these resources in the wild and leading to the erosion of traditional knowledge related to their use (Borelli et al. 2020). The current study found that WEPs in the area were particularly endangered by the expansion of agriculture into natural forests, the collection of firewood, and the unsustainable harvesting of these plants for timber production. The ever-increasing loss of these resources might be linked to population overgrowth and the escalation of poverty levels in the study districts. The findings of this study are consistent with other reports in Ethiopia such as in the Chilga district of northwestern Ethiopia [22], in Derashe and Kucha districts, South Ethiopia [11], in Bullen district, northwest Ethiopia [40]. The strong reliance of local communities, particularly unemployed youth, on natural plant resources for generating income to support and sustain their families is a recurring observation in the study districts that poses a challenge to WEP biodiversity management efforts.

Local communities in the study area employ various indigenous strategies for conserving and managing their natural resources. These strategies include cultivating wild edible plants like Asparagus africanus Lam, Amaranthus dubius Mart ex Thell, and Ocimum lamiifolium Hochst. ex Benth. in home gardens for medicinal purposes; Carissa spinarum L. and Zanthoxylum asiatica (L) Appelhans, Groppo & J.Wen for fencing; planting Euclea racemosa subsp. schimperi for shade; and preserving certain plants such as Ficus vasta Forssk and Ficus sycomorus L. due to their cultural and spiritual significance, including their use in worship and spiritual practices under these trees.

Conclusion

The study area is rich in WEPs, with high diversity and associated indigenous knowledge. Sixty-two WEPs documented, most of which were shrubs. The majority of which were sought for their fruits. Most WEPs collected for consumption from March to May and a large number of them were consumed only during periods of food shortage. The local people harvest the WEPs for not only foods but also for multiple other uses in the study areas have been reported. Fifty-two species mentioned for medicinal use. Syzygium guineense (Wild.) DC, Ficus sycomorus L., Allophylus abyssinicus (Hochst.) Radlk, and Ximenia americana L. were found to be the most preferred WEPs. Future evaluations of the nutritional value and pharmacological properties of wild edible plants (WEPs) should focus on those with high use value. It is essential for individuals and institutions to prioritize the management of threatened WEPs in collaboration with local communities, both in their natural habitats and through cultivation. Increasing public awareness about the significance of WEPs and promoting effective community-based management and conservation practices is crucial.

Limitations of the study

Limitations of the study include the lack of investigation into the marketability of wild edible plants and their potential adverse side effects in consuming them. This was due to constraints in time and resources, which prevented a comprehensive assessment of these important factors. Future research should focus on these areas to provide a more comprehensive understanding of wild edible plants. The “use value” index for assessing wild edible plants has limitations due to its reliance on subjective measures, which may fail to fully capture cultural, nutritional, and ecological significance. It can also overlook local preferences and practices, resulting in an incomplete understanding of a plant's importance. A more relevant approach that includes qualitative data and community insights could improve the evaluation of these plants.