Diversity of wild edible plants (WEPs) in Soro District

In this research, a total of 64 species of WEPs that belong to 52 genera and 39 families were documented. Further analysis showed that the family Flacourtiaceae had 4 (6.25%) species in 3 (5.77%) genera, Solanaceae 4 (6.25%) species in 2 (3.85%) genera, and Moraceae 4 (6.25%) in 1 (1.92%) genus. Other 36 families contributed 52 (81.25%) species distributed in 46 (88.46%) genera. These WEPs were collected from various habitats of forest patches, riverine areas, grasslands, agricultural lands, roadsides and homegarden yards with or without cultivated crops. Some wild edibles are cultivated by households in association with other naturally growing wild useful plants.

The records also included collected edibles, most of them used for herbal medicines with nutraceutical values in addition to supplementary as well as regular wild edible food sources during drought and famine which support human food security. For example, the roasted or cooked leaves and young shoots of Amaranthus dubius and Bidens pachyloma were mostly used during famine and consumed like some cultivated species of leafy vegetables such as Brassica oleracea var. oleracea and B. carinata, and the fruits of Ficus sycomorus, Ficus sur and O. spinosa are eaten by removing the exocarp, whereas the tuber of Dioscorea schimperiana is eaten as corm of Ensete ventricosum and tuber of S. tuberosum by cooking and peeling the thin exocarp.

FGD participants explained their observations that the diverse wild edibles are eaten more as snacks/refreshments and supplementary as well as regular wild food sources during food insecurity. A good number of the species are also said to have traditional medicinal and other uses. The WEPs provide edible fruits, leaves with terminal and lateral shoots/buds, tubers, and other parts used as chewing gum and spices of tea by the society. They are consumed by picking raw ripe fruits and mature leaves. Common examples in the study area are F. sur, F. sycomorus, S. guineense subsp. afromontanum, S. guineense var. guineense, W. ugandensis, Landolphia buchananii, C. spinarum, X. americana, Flacourtia indica, T. asiatica and P. thonningii. Some WEPs are eaten as regular wild food through rarely and other dominants are eaten as supplementary foods, in the study area, households and individuals during food shortages (e.g., F. sycomorus, F. sur, A. dubius, D. schimperiana, B. pachyloma and O. spinosa).

Specimens of these and other non-crop ethnobotanical edible plants were reported and collected from wild areas of dega, woinadega and kola agroclimatic zones within the altitudinal rages of 1345–2836 masl. Wise use of the above-explained results of edible leafy vegetables, tubers and fruits could ensure the sustainable availability to ensure the presence of food security as well as food sovereignty in the local community of the study area. However, today a large number of proportions of the population do not consume wild plants due to high dependency on staple food crops and they used wild edibles as accessory food sources.

Growth habits of wild edible plants

Of the total WEPs, trees took the highest growth form and proportion 22 (34.38%), liana took the least life form 1 (1.56%), whereas herbs (21) were the next highest life form followed by shrubs (16) and 4 climbers (Fig. 3). Trees were also categorized into 16 families and 18 genera, herbs 13 families and 17 genera, shrubs 11 families and 15 genera, and climbers 4 families and 4 genera. In contrast, liana had the least one family and one genus (Table 10).

Fig. 3

Growth habit (life form) of wild edible plants in Soro District

Frequency of wild edible plant parts and their proportion

Out of the total reported and eaten parts of wild edible food resources, fruits contributed the most significant palatable amount and percentage, accounting for 34 (53.13%) species, leaves follow in the second place as edible part, and the proportion accounted for 20 (31.25%) species (Table 2). Species known for having edible fruit and gum accounted for 5 (7.81%), leaf and fruit 2 (3.13%), tuber 2 (3.13%), and flower–inflorescence nectar accounted for 1 (1.56%). Hence, fruits and leaves are the most dominantly consumed and widely used edible wild plant parts in the study area, respectively. Of the wild edible plants, five species (F. sur, F. sycomorus, F. thonningii, F. vasta (Moraceae) and L. buchananii (Apocynaceae) also produced milky latex used as, chewing gum, as a plastering material and sipping sap (e.g., L. buchananii). Landolphia buchananii is used for making traditional play balls with parasitic mosses using milky latex that is produced from stem bark when cut or injured the bark.

Of the total reported WEPs, 34 are fruits; of them, 16 (47.06%) trees, 12 (35.29%) shrubs, 3 (8.82%) herbs, and 3 (8.82%) climbers. Of the whole leaf edibles (20), 2 (10%) trees, 3 (15%) shrubs, and 15 (75%) herbs contributed more proportion than trees and shrubs edibles. From 5 fruits and gum consumption plants, 4 (80%) are trees, and only 1 (20%) contributed liana; of the two leaf and fruit edibles, both species are herbs (100%); from 2 tubers category herb and climber contributed 1 (50%) each.

Mode of consumption

The people in the Soro District consume plants in raw ripe form without processing or upon cooking or roasting. The majority (68.75%) of the species are harvested and used in raw mature form by cleaning the dirty, washing the edible parts with clean water, and removing thick or thin non-edible epicarp and some hard stone endocarp seeds. Some 31.25% were eaten upon processing by chopping with a knife, and some were roasted or cooked using local clay pots and metallic cookers. In a few ripe raw wild edible plants, stems of some plant species are injured or cut. Sweet-tasting latex is released out and sipped by herd of cattle-keeping children and also used for chewing gum by painting or smearing the milky latex on the hand and allowed to dry (e.g., stem latex of L. buchananii, F. sur and F. sycomorus).

Marketability of wild edible plants in Soro District

People interviewed in the local markets informed that for two decades few species were sold to generate cash income, as is the case with S. guineense var. guineense, S. guineense subsp. afromontanum and seeds of Amaranthus caudatus was mainly sold as a food source in dega and woinadega, and rarely C. spinarum in kola agroecological settings. The community, in their habitats, consumed various wild food species in ripe and raw form. FGD informants also reported few WEPs were sold in the local markets to generate local income; they used the above two fruit edibles, seeds and rarely fruit of C. spinarum in kola agroecology.

Informant consensus on the most repeatedly and frequently reported WEPs

Certain wild edible plants were commonly used in the study area as the source of supplementary and regular wild food during food insecurity/famine than other wild food plants. As a result of this, the ripe raw fruit and leaf with shoot edible plants frequently reported as a source of stable food were F. sycomorus, reported by 147 informants and eaten fruits, A. dubius reported by 140 informants, and eaten leaf with shoots, D. schimperiana was reported as, regular wild edible by 138 informants and eaten tuber, and O. spinosa was reported 136 as regular food and fruit eaten, S. guineense subsp. afromontanum by 125 informants and eaten fruits as supplements, and B. pachyloma reported by 118 eaten leaves as regular with young shoots. The remained others were preferable supplementary wild edibles and all of them are potential plants for food security as well as food sovereignty in the study area for future food scarcity due to drought (Table 3).

Table 3 Informant consensus of most commonly eaten fruits and leaves with shoots eaten plants

The number of ICFs (0.72) which resulted in greater than 0, approximately 1, showed that different WEPs are used for various purposes for the local people who lived in the community in addition to food.

Preferences for some WEPs

The key informants ranked 13 edible fruits based on the degree of preferences among the highly cited wild edible plants in the Soro District. The wild edible fruit most preferred by the community scored “13” and the lowest score “1,” others being in between (Table 4).

Table 4 Simple preference ranking (SPR) values of the most commonly used top 13 wild edible fruits

The top thirteen (13) are the most preferable wild edibles based on the criteria of availability in common in the locality, pulp content,  organoleptic properties of tastes, smell, flavor, and other features, size of non-edible seeds and thickness of exocarp and one (1) is the least with relative to others. Among the compared WEPs, fruit edibles F. sycomorus was scored the highest and scored first (SPR = 96) based on fleshy pulp with very small seeds and better sensation of the flavor and used as regular wild food. Landolphia buchananii scored second (SPR = 94) and was used as supplementary wild food with better flavor and pleasant taste; S. guineense var. guineense was the third score (SPR = 93) and supplementary with suitable better taste, W. ugandensis scored fourth (SPR = 89) used as supplementary with light white flesh pulp and sweet taste and O. spinosa was scored fifth (SPR = 81); it has dense dark brown pulp with small sized berry seeds, with better flavor, used as regular wild food and others were scored and ranked accordingly.

In another comparison among preferable leaf edibles using ten key informants, Solanum nigrum (SPR = 75), A. dubius (SPR = 73), and B. pachyloma (SPR = 69) were the scored highest, second and third preference ranking scores (SPR); others supplementary wild edibles of A. caudatus, P. thonningii, Solanum sp, Urtica urens, Commelina benghalensis, Rumex abyssinicus and R. nervosus were ranked, respectively, with the SPR values of 68, 56, 53, 50, 48 and 37 and used as supplementary food (Tables 5 and 6).

Table 5 Direct matrix ranking score of 10 key informants of nutraceutical plant species with various other uses in Soro District based on use value criteria (5 = for the best, 4 = for very good, 3 = for good, 2 = for less used, 1 = for the least used and 0 = for no use category/value)Table 6 Result of paired comparison of eight wild edible plant species used by the people in the study district

The top ten potential WEPs were quantified using the index of fidelity level (Table 7). The ripening and availability of these species varied and were mainly used to fill gaps in food shortages. F. sycomorus, A. dubius, and D. schimperiana had higher scores and were used as more regular wild food sources including O. spinosa, whereas L. buchananii, C. spinarum, X. americana and P. thonningii were reported for use as supplementary wild food sources. Both W. ugandensis and S. guineense subsp. afromontanum were noted for being used as additional and regular wild edibles, particularly during famine and the food insecurity gaps. These species required sustainable use and conservation priority in the community of the study area.

Table 7 The relative value of fidelity level for potential wild edible plants in the study areaIndigenous knowledge distribution in different socio-demographic members

More WEPs were reported by male informants on average (12.52 ± 6.07); frequently reported/cited 1553 (84.68%) of all respondents reported WEPs (1834) than females (9.37 ± 3.62); cited 281 (15.32%); and the statistical comparison is also significant (P < 0.05). This is usually because males are movable from one area to another, and they had opportunities to gain and share as well as quote more indigenous knowledge about WEPs use than females (owners of households). Although comparing gender informants for indigenous knowledge practices based on WEPs’ preparation for feeding, women are better knowledgeable and familiar with food preparation and cooking, caring for their families and children in their house than men. Key informants frequently reported 474 (25.84%) species, and general informants 1360 (74.15%) frequent species, and significantly varied (P < 0.05) at the mean average number (18.23 ± 6.43).

On the other hand, there were insignificant differences (P > 0.05) occurred among educational status, agroclimatic zones, and age categories even if a more frequent number of WEPs were reported and accounted by literates 1044 (56.92%) than illiterates 790 (43.07%); woinadega 1318 (71.86%) than dega 365 (19.90%) and kola 151 (8.23%). As well as more indigenous knowledge of WEPs was also frequently reported by old ages (> or = 60 years); 735 (40.07%) and an ages in-between adult ages (36–59 years); 635 (34.2%) than in-between young ages (18–35 years); 464 (25.30%). It might be due to less knowledge transfer among the 26 key and 128 general interviewed informants.

Based on the distance of informants relative to the main town, frequently more WEPs 1376 (75.03%) were reported from far rural areas (> or = 5 km) than nearby 458 (24.97%) of (< 5 km), indicating that people were more relation with the plants and more vegetation availability in the far rural community than urban. The frequently reported result indicated that more varieties of WEPs can be available in rural communities due to potential vegetation sites along forest patches away from an urban community. Statistical it also varied insignificantly (P > 0.05) with distance from the town.

Male informants reported more information on WEPs with ethnobotanical knowledge than females and varied numbers of wild edible plants; key informants have rich knowledge information on wild food plants than general informants when they computed their knowledge (Table 8). Frequently more species were reported from woinadega than dega and kola agroclimatic zones, as well as the distance from the town or population center was more in localities closer to natural forests and woodlands compared to urban areas.

Table 8 Statistical test of significance using one-way ANOVA the average number of reported WEPs among various variables in the study area, Soro District

Insignificant differences (P > 0.05) occurred in the number of wild edible plants reported by illiterate and literate; young, adult, and elderly; near and distant. Numerous WEPs were frequently reported from dominant informants living in areas from woinadega agroclimatic zone. Key informants reported more ethnobotanical knowledge on WEPs relative to the general and age-old, middle and younger; rural dwellers than urban.

Nutraceutical wild edible plants

Of the 64 WEPs, 53 were reported for traditional medicine to treat one or more than one human and livestock ailments (Table 9). Leaves were reported the highest numbers (54.02%) by informants’ citations, followed by roots (18.97%), and other proportions of small use citations accounted for 27.01%, which include fruit, actively growing buds, stem bark, aboveground and belowground part, whole part, latex, and resin. Due to the widely used conventional medicinal plants by indigenous people, fresh leaves with buds were dominantly used, followed by fresh roots and fruits. Of the total WEPs, 53 nutraceutical plant species were used to treat 70 human ailments, 18 livestock ailments, and 5 for human and livestock ailments. One or a combination of two or more wild edible plants treated those ailments.

Table 9 Some nutraceutical wild edible plants used for the treatment of human livestock ailments

Some species (1) A. africanus, (2) C. spinarum, (3) Cordia africana, (4) X. americana, (5) S. nigrum, (6) Physalis peruviana, (7) O. spinosa, (8) T. asiatica, (9) L. buchananii, (10) Moringa stenopetala, (11) Erucastrum arabicum, (12) F. sur, (13) F. sycomorus, (14) S. guineense var. guineense (15) S. guineense subsp. afromontanum, (16) D. schimperiana, (17) Balanites aegyptiaca, (18) Dovyalis abyssinica, (19) P. reclinata, (20) P. thonningii, (21) Trichocladus ellipticus and (22) W. ugandensis were the most commonly reported wild edible and medicinal plants in the study sites by different informants used the same edible and medicinal plant parts including different medicinal and wild edible used parts. Of these food security edibles, medicinal plant species No. 1, 4, 7–9, and 12–22 were locally extinct plants. Therefore, they need attention for in situ conservation. Here, M. stenopetala rarely occurs species in the kola agroclimatic community; it is naturalized in the wild of the study area, and it came from another site. Indigenous people practice growing and diversifying in wild natural habitats to adapt to kola (semidesert) around Gibe River for the source of traditional food security of leaf vegetable as well as local food sovereignty.

Agroclimatic zones and abundance of WEPs in various habitats

Natural habitats are home to renewable wild edible plants. In the study area, WEPs were gathered from different in situ habitats with various percentages (Table 10). Informants collected more WEPs from wild habitats 59 (92.19%) than non-wild habitats from semi-wilds 5 (7.81%). Large in and around purposively sampled vegetation areas of forest patches and community homegardens even if they were rare due to human activities, mainly deforestation for agricultural expansion and settlements. Few WEP species C. africana, Mimusops kummel, S. guineense var. guineense, S. guineense subsp. afromontanum and W. ugandensis are economically very important trees in addition to their uses as wild edible and medicinal plants in the area.

Table 10 Ethnobotanical wild edible plants diversity collected in Soro District, southern EthiopiaThreats and conservation strategies of wild edible plants

In the study area, human activities (anthropogenic factors) are the main threats to vegetation which causes the decline of multi-purpose indigenous wild food plant species. Deforestation is one of the leading impact factors due to the new settlement and agricultural expansion. Cutting/illegally hunting trees and shrubs from remnant forest patches, grass, riverine and bush lands unwisely for fire and selling local charcoal, timber/furniture production, dry fence, house construction, and Eucalyptus trees substitution are also threats that decrease potential vegetation species that provide wild edible plants for food security. For example, C. spinarum, C. africana, F. sur, F. sycomorus, D. schimperiana, L. buchananii, O. spinosa, P. thonningii, S. guineense var. guineense, S. guineense subsp. afromontanum, W. ugandensis and X. americana need conservation priority in the community. Overgrazing in the protected vegetation areas, lack of attitudes toward bare land replantation to form afforestation, less knowledge share for a young new generation, and changing climatic condition in the environment also contributes to the threats.

Focus group discussions in the district in the 13 sites of the study kebeles, above various threats, were identified and discussed and followed by suggestions for solutions to conserve and manage those indigenous potential wild edibles and/or medicinal plants in the community, which help to conserve more other potential plants including wildlife in their natural habitats. Mainly in situ conservation of plants in their natural habitats as well as ex situ conservation and awareness education for communities. Domestication of indigenous potential wild edible and medicinal plants by local people around home guards, agricultural land, roadsides, shade, nursery expansion, reducing exotic plantation (e.g., Eucalyptus trees), reforestation, and afforestation. Hence these strengthening conservation strategies of vegetation (remaining forest patches) in the study area. These are with the help of nearby governmental institutes with community linkage.