Traditional knowledge and consumption of wild edible plants in rural households, Limpopo Province, South Africa

Abstract

Background

Globalisation, urbanisation, and modernisation all influence traditional knowledge. More specifically, the introduction of exotic plants, historical policies, stigma attached to consuming wild edible plants (WEPs), changes in lifestyles, and environmental factors are reshaping peoples’ uses and knowledge of WEPs. This study assessed the relationship between ethnobotanical knowledge and consumption of WEPs in rural villages in the Polokwane and Aganang local municipalities, Limpopo Province, South Africa.

Methods

This study was conducted in four villages in the Limpopo Province, South Africa, between May 2018 and June 2019. Data about WEPs were collected using a household survey questionnaire administered to a total of 120 participants stratified by age and gender. Additionally, a free list of WEP species known by participants was collected as well as data on the traditional uses of each species.

Results

We found that WEPs are generally well-known in the area, as participants listed an average of 17.7 ± 5.0 (8.4 ± 2.4 wild fruit species) and (9.3 ± 2.6 wild vegetable species). There was a significant difference between the number of species listed by age group, with the elderly listing a higher mean number of species (9.3 ± 2.6) compared to adults (8.1 ± 2.5) and the youth (7.8 ± 1.7). Vangueria infausta, Sclerocarya birrea subsp. caffra, Ximenia caffra, Amaranthus retroflexus, Citrullus lanatus, and Cleome gynandra were among the most listed species. There was a positive correlation between knowledge of WEPs and consumption rates. Most of the knowledge about WEPs was learnt from a family member (89%), own observation (86%), and a village elder (75%). This knowledge was mostly acquired from childhood through oral tradition (63%), through participation (21%), and consumption (12%).

Conclusions

Future preservation of WEPs knowledge could be encouraged by formalising indigenous knowledge in the education system and promoting WEPs in the media.

Background

Indigenous knowledge has been a pivotal part of human history of survival and adaptation. Indigenous communities worldwide have utilised natural resources for food and medicine, enabling them to thrive in different environments [1, 2]. Indigenous knowledge is defined as knowledge that is held by local people of a particular geographical area and culture, which is passed from generation to generation [3]. This knowledge forms part of the culture of people in rural and urban communities and it can be applied to many aspects of their daily living, such as water resource management, disaster management, agriculture, natural resource management, medicine, and ethnobotanical knowledge of food plants and many others [4]. In recent times, the contribution of Indigenous knowledge has been acknowledged in efforts to address global challenges such as climate change [5], biodiversity loss [6], and for food security [1]. With the rising levels of malnutrition due to poor intake of micronutrients in poor regions across the world (including in Africa) [7], the erosion of indigenous knowledge related to traditional or wild food plants would be particularly concerning. This is because several studies have shown that the intake of traditional fruits and vegetables is limited and particularly low among urban populations in various countries including Namibia [8], Bolivia [9], and South Africa [10,11,12]. A contribution to this decline in consumption might be the erosion of ethnobotanical knowledge about traditional plants, especially among the youth [4, 9]. There are several factors implicated in the decline of indigenous knowledge related to wild edible plant species [4]. These include the introduction of non-native cultivated species and varieties, historical policies, stigma attached to consuming Wild Edible Plants (WEPs), changes in lifestyles, and environmental factors. According to Fox & Norwood-Young [13], precolonial societies in South Africa ate a diet that was mostly comprised of wild plants, wild cereals, milk, and meats, with wild vegetables consumed as a daily relish while meats were consumed occasionally. The introduction of cultivated species through colonisation and modern agriculture catalysed a rapid dietary change, posing a threat to the local traditional food systems [11]. This was aided and abetted by agricultural and health policies that promoted the cultivation and consumption of non-native, cultivated species at the expense of the indigenous ones [4, 14].

Negative attitudes related to the consumption of WEPs, especially by the youth, have contributed to the knowledge erosion as traditional plant foods are often regarded as unsophisticated or poverty foods [15, 16]. Changes in lifestyle have meant that young women today are increasingly losing knowledge on the collection and preparation of wild plants because their participation in these activities has declined [10, 17]. Lastly, environmental challenges such as climate change and deforestation threaten the distribution and abundance of many wild plant species. Habitat loss induced by deforestation and other land clearing activities, as well as climatic events such as droughts, contribute to the local decline or disappearance of certain WEPs [4, 18]. These challenges need to be addressed to ensure that ethnobotanical knowledge relating to WEPs remains intact. There are several ways that indigenous knowledge challenges can be addressed, including through policy change and implementation. South Africa’s indigenous knowledge policy of 2004 laid a foundation of highlighting the key issues that require attention, such as knowledge preservation and documentation [19]. It also placed South Africa as one of the few countries on the continent where the government is promoting the diversification of knowledge [20]. Despite these strides, the policy has its shortcomings.

According to Green [20], one of the challenges is related to the commercialisation of knowledge where intellectual property rights and patents in relation to shared knowledge need to be established. Additionally, Mhlongo [21] bemoaned the lack of indigenous knowledge content in public libraries. Secondly, related to the first, is the issue of indigenous knowledge sharing or knowledge transfer at the household level. Since the elderly are usually more knowledgeable about wild plants and their use [22], they can pass on the knowledge to the younger generation to promote continued future use [4]. Lastly, the negative attitudes, perceptions, and stigmatisation of the consumption of WEPs, especially by the youth, also need to be attended. This could be done by integrating indigenous knowledge systems into higher education to create opportunities for students to learn about and appreciate the knowledge of elders [23]. This is particularly pertinent because the consumption of WEPs typically depends on whether people know the appropriate plant species [24].

The idea of preserving indigenous knowledge is accompanied by an assumption that the more knowledge people have about WEPs is the more likely they are to consume them. For example, Ladio & Lozada [25] showed that in Argentina, people who know more edible plant species consume them more frequently. However, according to Reyes-Garcia et al. [24], in Bolivia, the relationship between knowledge and consumption does not always correlate. Their study showed that the relationship between those two variables can be influenced by socio-economic factors such as location, i.e., how isolated or accessible villages are and how accessible substitute foods (cultivated crops) are [24]. Therefore, socio-economic change can create or widen the gap between people’s ethnobotanical knowledge of WEPs and their use and consumption [24].

It is evident that the preservation of indigenous knowledge is paramount for future use. Additionally, the consumption of WEPs differs according to an individuals’ level of ethnobotanical knowledge. Since an individuals’ level of ethnobotanical knowledge changes throughout their lifetime [24], this means that individuals of different ages and socio-economic backgrounds are likely to have varying levels of knowledge of WEPs. Within this context, this paper assessed the relationship between ethnobotanical knowledge and consumption of WEPs in a subtropical region of South Africa. The objectives of the study were to assess: (1) the number of wild edible fruits and vegetable species participants know; (2) how their knowledge of these species was produced and transferred; (3) which WEPs species are consumed and how often; and (4) if there is a correlation between the number of species known, the number of species consumed and how this changes with age. This study hypothesised that there would be a positive relationship between the number of species known with the number of species consumed, as well as that the number of species known would increase with age.

Materials and methods

Study setting

Aganang local municipality¹

Aganang Local Municipality is small municipality (1852 km²) in the Capricorn district of Limpopo Province, South Africa (Fig. 1). This municipality is located between the Tropic of Capricorn to the north and 24°00 latitude to the south. It spans two vegetation types, i.e., Makhado Mixed Bushveld and Polokwane Plateau Bushveld [26]. The Makhado Mixed Bushveld is characterised by a variety of tree genera, with Combretum, Terminalia, Senegalia and Vachellia dominating, along with diverse grasses and shrubs [27]. In contrast, the Polokwane Plateau Bushveld is more open and dominated by Burkea, Combretum, and Senegalia species [27]. The climate of Aganang is defined by dry winters and wet summers, with average maximum temperatures reaching 24 °C in winter and 32 °C in summer, alongside a mean annual precipitation of 550 mm [28]. As a rural municipality, Aganang has a population of approximately 131,164 residents spread across 33,918 households within 106 villages [29]. Demographically, 17% of the population is aged 14 years old or younger, while 10% are elderly (over 65), and 53% fall within the working-age group (15–64) [29]. The unemployment rate stands at a significant 50%, with youth unemployment even higher at 65% [29]. Educationally, adult literacy rates are at 72%, and youth literacy rates are at 86%, both below the national averages of 80% and 95%, respectively [29]. Economically, many households (29%) report an annual cash income between R9,600 and R19,600 ($528—$1078), while about 13.2% have no cash income [29]. The municipality experiences a negative economic growth rate of −1.13% over the past decade. Much of the land falls under communal administration by traditional leaders [29]. The land is used for subsistence agriculture, livestock farming, forestry, residential areas, mining activities, and the collection of non-timber forest resources (such as firewood, medicinal plants, wild foods, craft, and building materials) with subsistence agriculture being the primary economic driver [30].

Fig. 1

Study setting map

Data collection

Permission to conduct the study was obtained from the relevant authorities in all the sampled villages. A stratified purposive sampling technique was used to choose 120 individuals categorised into three age groups and two gender groups. The 120 participants were selected from villages in both the Moletjie (Mphela and Lonsdale) and the Matlala areas (Mabopane and Tibane). The 120 participants were divided into three age groups (youth 18–35; adult 36–59; and elderly > 60) of 40 participants, balanced between 20 males and 20 females.

A household questionnaire was used to collect data on the consumption and traditional knowledge of WEPs. The questionnaire included both closed- and open-ended questions. A free list of species known by each respondent was collected as well as data on the traditional uses of those species. Participants also provided information on how this knowledge was obtained, from whom it was learnt and how it was transferred. Additionally, data of the consumption patterns of WEPs were collected, including the WEP species and the frequency of consumption. On top of listing species to demonstrate the extent of knowledge, participants were asked to provide information about locations where the species were collected besides the home garden, the months when the species are available, the description of the taste and other uses of the species. Prior to the field work, the study approach and the questionnaire were approved by the Rhodes University Human ethics research Committee (No. ES18/26).

The interviews were conducted in the local language of Northern Sotho in which the researcher and assistants were fluent. Interviews took between 45 and 60 min, and the responses were directly recorded on the questionnaire as the responses were given. These data were collected between May and June 2018 and June 2019. Interview data were supported by confirmed by field observations and field walks in participants’ home gardens and in the nearby fields where WEPs are available and collected. Collected specimens were submitted to Dr Bronwyn Eagan at the Larry Leach Herbarium, University of Limpopo, where they were identified and kept.

Data analysis

Interview data were coded and entered into a Microsoft Excel spreadsheet, and then transferred into SPSS for analysis. Data were summarised and descriptive statistical analyses, such as frequency distributions and measures of central tendency, were performed. Frequency indices (Fidelity Level) were calculated using the following formula: FL = (Np/N) × 100 where Np is the number of respondents reporting the use of a certain species and N = the total number of participants. Two-way ANOVA tests were performed to determine statistical significance between age and gender groups with various variables. Tukey’s Honest Significant Difference tests were used to perform post-hoc tests. Correlation coefficients were computed to determine relationships between the number of listed wild fruits and vegetables as well as the relationship between listed species and consumed species.

Results

Participant profile

The average age of participants was 48.6 ± 18.9 years, ranging from 19 to 95 (Table 1). The average age for the youth group was 27.8 ± 5.0 years, ranging from 19 to 35, for the adult group it was 46.8 ± 6.1 years (36–57), and the elderly group had an average of 71.2 ± 7.5 years, ranging from 61 to 95. Half of the participants (50%) in the youth group had completed a tertiary qualification, while 47.5% had completed secondary schooling. About 37.5% of the youth are students, 12.5% are employed full-time, 15% are self-employed while 20% are unemployed. Most of the participants in the adult group (55%) had completed a secondary education and 40% of them are unemployed. Most of the elderly (45%) have completed primary schooling, 85% are retired and not working. Most of the participants (82%) grew up in a rural village, 8.3% in a township, and 7.5% in farms. Most of the participants (55%) have always stayed in rural villages while 40% have lived over half of their lives in the villages.

Table 1 Summary profile of respondents (n = 120)

Traditional knowledge of WEPs

Wild fruits

All the participants indicated some knowledge of WEPs species. The average number of wild fruit species listed by participants was 8.4 ± 2.4, ranging from four to sixteen species. There was a significant statistical difference between the number of wild fruit species listed by age group (F = 4.96, p = 0.009), being highest amongs the elderly (9.3 ± 2.6) compared to the adult group (8.1 ± 2.5) and the youth group with the least (7.8 ± 1.7 species). Post-hoc tests showed a statistical significance was observed only between the elderly group and the youth group (p = 0.011). There was no significant statistical difference between the number of species listed between genders (F = 0.45, p = 0.503), with males listing 8.5 ± 2.4 and females 8.2 ± 2.4 species. Participants free-listed a total of 24 wild edible fruit species of which 22 were identified to species level (Table 2).

Table 2 Listed wild fruit species (by number of users)

Vangueria infausta was the most frequently listed species, mentioned by 104 participants with a frequency index of (87%), followed by Ximenia caffra (83%), Sclerocarya birrea (64%), Grewia flava (63%), and Ziziphus mucronata (48%) (Table 2). The frequency index also showed that the least mentioned species were Grewia caffra (1%) and Flueggea virosa, (1%) followed by Boscia albitrunca (2%), Ficus sycomorus (3%), and Ficus sansibarica (3%). Participants demonstrated knowledge about many species, for example by mentioning that Vangueria infausta also grows widely in the abandoned fields, it is mostly harvested around February/March and the fruits also attract snakes. Similarly, Sclerocarya birrea also grows at the old fields and fruits between December to March, has a sweet/sour taste, and can be fermented into an alcoholic beverage.

Wild vegetables

A slightly higher average number of 9.0 ± 2.98 wild vegetable species, ranging from four to seventeen were listed per respondent as compared to wild fruits. There were no statistically significant associations between the number of listed wild vegetable species with age group (F = 1.83, p = 0.165) nor gender (p = 0.134). In terms of age group, the elderly listed an average of 9.8 ± 3.0 species, the adult group listed 8.6 ± 3.0 species, ranging from four to fifteen, and the youth listed an average of 8.8 ± 2.9 species ranging from four to fourteen. Like wild fruits, males recorded a slightly higher mean of 9.4 ± 2.9 species than 8.6 ± 3.0 females. A total of 18 wild vegetable species were mentioned, and all but one were identified (Table 3).

Table 3 Listed wild vegetable species (by number of users)

Vigna unguiculata was the most frequently listed vegetable species with a frequency index of 93% (Table 3), followed by Citrullus lanatus (92%), Cleome gynandra (84%), and Amaranthus retroflexus (76%). The least listed species were Momordica balsamina (1%), Waltheria indica (5%), Convolvulus farinosus (14%), and Oxygonum sinuatum (14%).

There was wide agreement that Amaranthus retroflexus grows widely as a “weed” at crop fields, it is available from December to around February, and it can be cooked, dried, and stored for later consumption. Corchorus tridens is well known for being slimy and slippery when cooked. Parapolydora fastigiata also grows in the rainy season, it can also grow around crop fields, and it is described to having a bitter taste.

Table 4 shows that most of the respondents who know a high number of species are elderly and have been residing in the village all their life. They are also among the respondents who consume a high diversity of WEPs and have lower education levels. In contrast, respondents who know relatively few species are a mixture of the youth and adults who have not resided in rural villages for most of their lifetime. They also consume fewer WEPs species and most of them a have a tertiary qualification. However, there was no significant correlation between the number of WEPs known and education level (r = 0.11, p = 0 0.233).

Table 4 Summary profile of the most and the least knowledgeable respondents

There was a strong positive correlation between the number of wild fruits and wild vegetables listed per respondent (r = 0.67, p < 0 0.0001) (Fig. 2).

Fig. 2

Correlation between the number of wild fruits and wild vegetables listed per respondent

Knowledge production and transfer of WEPs

Knowledge about the identification, use, and taste of WEPs was learnt and passed from diverse sources, although most of the participants across all age groups agreed or strongly agreed to have learnt from a family member, with the level of agreement ranging from 90% for adults to 98% for the elderly (Fig. 3). This was followed by respondents who learnt from their own observations (86%) across all age groups and those who learnt from a village elder (75%). Most of the participants disagreed that knowledge about WEPs was learned from the media or from school, with an average disagreement level of 79% and 66%, respectively.

Fig. 3

Sources of knowledge of WEPs by age group. *NS not sure, SD strongly disagree, D disagree, N neutral, A agree, and SA strongly agree

Most of the participants (90%) learnt about WEPs during their childhood, with knowledge acquired through oral tradition (63%), followed by participation in collection (21%), through consumption (12%) and to a lesser extent, through observation (4%). It is possible that the majority (90%) who learnt about WEPs from childhood would have also learnt through consumption. Most participants (83%) acknowledged that they have passed this knowledge to others. Elders reported passing on the knowledge to their children (44%), friends (29%), grandchildren (18%) and siblings and other relatives (9%). Similarly, the youth pass their knowledge mostly to their friends (67%), siblings (19%) parents (11%) and relatives (3%).

Lifelong learning about WEPs

Most participants (88%) acknowledged to continually acquiring new knowledge relating to WEPs. In our study, new knowledge refers to the recent (past 5 years) acquisition of a new piece of information about a WEP species, such as discovering the use of a previously unknown species, discovering a different use and value of the species. Approximately one-third of the elderly (35.8%) said that they had acquired some new knowledge about one or more WEPs in the past 5 years, compared to adults (33%) and youths (31%). There was no statistical difference in acquiring new knowledge between age groups (F = 5.758, p = 0.451) and gender (F = 1.771, p = 0.621).

Participants provided a variety of newly learnt knowledge that was categorised into themes. Most of the newly learnt information pertains to health and nutrition (85%), followed by economy (16%), culture (4%) and the environment (1%). In terms of health and nutrition, participants reported learning how WEPs are nutritionally dense foods and species like Ziziphus mucronata leaves have medicinal value. Economically, participants learnt that WEPs are sold in urban areas where they are most in demand. Environmentally, participants learnt that some species might disappear because of poor rainfall.

Loss of traditional knowledge

Despite the knowledge participants have about WEPs (including new knowledge), the majority (95%) perceive traditional knowledge of WEPs to be eroding. The most cited reasons for this were the growing dependence on cultivated foods (91%), change in lifestyles (88%), lack of youth interest (83%), lack of promotion of WEPs in the media (69%), and lastly, the lack of education about WEPs in schools (61%). Even most of the youth group conceded (68% agreed) to not being interested in WEPs and thus contributing to the loss of knowledge (Fig. 4). Out of all the reasons provided, participants disagreed that the lack of interest from elders to pass knowledge was not a contributing factor to the loss of traditional knowledge of WEPs.

Fig. 4

Reasons for loss of tradition WEPs knowledge by age group. *NS not sure, SD strongly disagree, D disagree, N neutral, A agree, and SA strongly agree

Species collection

Most participants communicated that they had collected WEPs in their childhood. Most participants (92%) collected wild fruits more than wild vegetables (80%), although consumption rates were similar (96% for wild fruits and 94% for wild vegetables). Today, participants still collect wild fruits and vegetables. Participants (88%) indicated that they purposely left their houses to collect WEPs rather than it being an ad- hoc activity. Most of the WEPs were collected around their home gardens (45%), around the village (33%), in the fields (20%) and on mountains and riparian areas (2%).

Consumption of WEPs

Wild fruits

All the participants indicated that they consume wild fruit species. On average, participants consumed 5.2 ± 1.19 wild fruit species, ranging from two to eight. The adult group consumed 5.0 ± 0.9 species, compared to the youth and elder group with 5.3 ± 1.3 and 5.4 ± 1.2 species, respectively (H = 3.72, p > 0.05). Females consumed an average of 5.3 ± 1.20 species and males consumed 5.2 ± 1.19 species (p > 0.05).

Frequently consumed wild fruits

Participants listed a total of 18 wild fruit species that they have consumed in the past 5 years. The frequency index showed that the most consumed wild fruit species were Vangueria infausta (70%), followed by Englerophytum magalismontanum (62%), Grewia flava (50%), Sclerocarya birrea (45%), and Ziziphus mucronata (40%) (Fig. 5). The frequency index also showed that the least consumed species were Ximenia caffra (3%) and Ehretia rigida (5%). Most of the participants (78%) perceive the abundance of wild fruits to be in decline because of indigenous trees being cut and a shortage of rainfall, while 20% do not see any changes in abundance. As a result, most participants (83%) believe that consumption of wild fruits is declining.

Fig. 5

Frequently consumed wild fruit species

Wild vegetables

A slightly higher average number of 5.42 ± 1.55 wild vegetable species were consumed, ranging from one to nine species. There was no significant statistical difference between the number of species consumed between age groups (H = 2.58, p > 0.05), being 5.7 ± 1.50 for the youth followed by the elderly group (5.5 ± 1.53) and the adult group (5.1 ± 1.59). There was also no significant difference by gender (p > 0.05), with males consuming 5.5 ± 1.46 species and females 5.3 ± 1.64 species.

Frequently consumed wild vegetables

On average, respondents had consumed a total of 16 wild vegetable species in the past 5 years. Seventeen of the sixteen wild vegetable species were identified. The frequency index showed that the most consumed wild vegetables species were Amaranthus retroflexus, Cleome gynandra, and Citrullus lanatus leaves, all consumed by 44% of the participants (Fig. 6). The frequency index also showed that the less frequently consumed species included unidentified species such as Tlowane (6%), Mophato (2%), and Waltheria indica (5%). Unlike with wild fruits, just less than half (49%) of the participants perceive the abundance of wild vegetables to be declining while 42% see no difference in the past 5 years. However, most participants (62%) indicated that the consumption of wild vegetables is decreasing, while 30% believe that the consumption has stayed the same.

Fig. 6

Frequently consumed wild vegetable species

Knowledge and consumption

Correlation between knowledge and consumption of WEPs

There was a positive significant correlation between participants’ knowledge of WEPs and their consumption (r = 0.42, p < 0.001). In this case, the higher the number of WEPs species known, the higher the number of WEPs species consumed. Related results were observed when wild fruits and wild vegetables were analysed separately; wild fruit species (r = 0.31, p < 0.001) and wild vegetables (r = 0.42, p < 0.001).

However, there were slight differences when the correlation was analysed based on gender and age groups. In terms of gender, the correlation between knowledge and consumption was strong, positive, and significant for both males (r = 0.51, p < 0.001, n = 60) and females (r = 0.34, p < 0.001, n = 60). In relation to age groups, there was positive and significant correlation of knowledge and consumption for the adults (r = 0.67, p < 0.001, n = 40) and the elderly (r = 0.34, p < 0.05, n = 40), but not the youth (r = 0.28, p > 0.05, n = 40).

Discussion

Traditional knowledge of WEPs

On average participants listed 17.4 ± 5.0 WEP species, which is significantly higher than similar studies such as Turreira-García et al. [31] in Guatemala, where participants free-listed an average of 7.2 ± 0.7 species. However, differences in climatic conditions and vegetation types, and hence possibly local species richness, between these studies should be noted. The Guatemala study was conducted in a region characterised by subtropical forests with a higher mean annual rainfall compared to this study [31]. Studies that determine WEPs knowledge through the free-list method are rare in locations that have similar environmental and climatic conditions to this study. Vangueria infausta (87%), Ximenia caffra (83%), Vigna unguiculata (93%), and Citrullus lanatus (92%) were among the most listed species. This might be because these species grow abundantly in people’s backyards and surrounding areas; hence, they are frequently recalled. This was confirmed by field observations and field walks in participants’ home gardens and in the nearby fields where WEPs are available and collected.

Knowledge is not shared equally among different members of society [32]. This study corroborated this by showing that the elderly were more knowledgeable about WEPs than the youth. This also supports the study’s hypothesis that knowledge of WEPs species would increase with age. This could be attributed to factors such as modernisation that has reduced the amount of time young people spend in the natural environment [33]. Bruyere et al. [34] noted that as more young people pursue formal education, there is a shift away from pastoralism and agrarian livelihoods which results in reduced exposure to and interest in, and unfamiliarity of the youth with some traditional knowledge. Their study found that young boys in Kenya who participated in the formal education system had less knowledge of traditional plant species than those who practised traditional pastoralism [34]. Another study in South Africa, identified the schooling system to be the driving force responsible for changing value systems among the youth, undermining traditional knowledge transmission and contributing to the disruption of traditional knowledge acquisition [35]. Additionally, formal education contributes towards traditional knowledge loss because it usually lacks any indigenous knowledge content in the curriculum [21].

The elderly have a higher ethnobotanical knowledge of WEP species because they have lived longer and thus have more cultural and lived experience of them, and even continue to learn new things about WEPs despite their long familiarity with and use of them. This study showed that the most knowledgeable participants were those who had resided in rural villages all their lives. Even though most of the youth have also lived in rural villages all their lives, the elderly have accumulated more knowledge because they lived longer and secondly, some of them have migrated from different localities to their current residence because of new opportunities or marriage. This migration might have exposed them to a new set of species that may have not been available at their village of origin which might have been in a different ecological zone. The relationship between age and plant knowledge is corroborated by other studies such as [36] and [37] who found a correlation between plant knowledge acquired over time in Venezuela and Bolivia, respectively.

There was no significant difference in the number of wild fruits and vegetables listed between genders. This is contrary to widely held belief that women are more knowledgeable about wild vegetables than men because often they are the ones responsible for collecting and cooking them [14, 38, 39]. From this study, men and women listed almost equal numbers of wild fruits and vegetables. Ghorbani et al. [40] observed similar findings where slight differences in listed species between men and women were found in China. Dovie et al. [41] also found no gender differences in the Bushbuckridge area of Limpopo Province.

Knowledge production, transmission, and loss

Knowledge about WEPs is mostly acquired and transmitted socially through relatives or community members [31]. This indeed was the case as most participants learnt their knowledge of WEPs from a family member, a village elder, and from their own observations. WEPs knowledge was mostly acquired during childhood through oral tradition, participating in collection and during consumption. These sources of knowledge corroborate Zarger’s [42] stages of knowledge acquisitions characterised by familiarisation, observation, and participation. As young children, participants acquired knowledge about WEPs by assisting their parents in the fields, they learnt by observing, by helping to prepare meals, and also through consumption [31]. This study also supports others [31, 34] that found a negative relationship between formal education and traditional knowledge, as most of the participants disagreed to have acquired knowledge from school or other media sources. However, this study did not find a correlation between knowledge and education level.

Most participants affirmed passing on their knowledge of WEPs to other people. Knowledge passage usually occurs from the older to the younger generations (vertical transmission) or between peers (horizontal transmission) [43]. From this study, the elderly passed knowledge mostly to their children and grandchildren, while the youth passed to their friends and siblings. The continuous transmission of knowledge across and between generations affirms that the acquisition of knowledge is a lifetime process [44]. Indeed, the learning about WEPs never stops as both the elderly and young participants reported learning added information in the past 5 years about species they did not know before, benefits that they were not aware of and preparation methods they were not familiar with. However, Zarger [42] reports that knowledge fades away when one becomes too old, usually because they become frail and forgetful. This is why it is vital to transfer indigenous knowledge to the younger generation to ensure its future preservation [4].

The decline in indigenous knowledge over time is observed by several studies [31, 45,46,47]. Even though participants in this study have demonstrated their knowledge of local species, they perceived knowledge of WEPs, in general, to be eroding. This could be due to factors such as the dependence on non-native cultivated foods, changes in lifestyles, lack of youth interest and lack of any traditional knowledge content in formal education. Their perception of indigenous knowledge loss is not limited to their localities. Similarly, factors such as technological change, access to new food products, and access to markets that may be cause by rural/urban migration may be perceived to contribute towards this loss in other location (rural and urban) too [3, 44, 45].

Knowledge and consumption of WEPs

Consumption of WEPs

The most consumed wild fruits species were Vangueria infausta, Englerophytum magalismontanum and Grewia flava. The fruits of Vangueria infausta are small, round, and multi-seeded; they are green when raw and brown when ripe and dried, they produce a sweet–sour taste and are available from December to April [11]. In another study, Vangueria infausta was one of the most occurring fruit tree species in many of the home gardens in rural KwaZulu-Natal [48]. The abundance of this species is most likely the reason for its frequent consumption. The most consumed wild vegetables species were Amaranthus retroflexus and Cleome gynandra. A study from a similar location as this study (Capricorn municipality, Limpopo Province) found these two species to be in the top five of the most maintained and cultivated species in people’s home gardens; the only two traditional vegetable species in that list alongside Spinacia oleracea and Allium cepa [49]. Indeed, various Amaranthus spp. are commonly consumed in rural villages throughout South Africa [11, 15, 49, 50].

From a total of 24 consumed wild fruit species and 18 wild vegetable species, participants had consumed an average of five species of each in the past 5 years. The diversity of species consumed was similar across age and gender groups. This finding contradicts several studies in South Africa that found elderly females to be the most frequent consumers of WEPs, especially wild vegetables [10, 17, 51]. However, it is possible that the similar diversity of species consumed has little to do with differences in age and gender, but rather with the availability and accessibility of the species in a locality. Mncwango et al. [10] found that the major constraint to wild vegetable consumption was the lack of availability all year-round. But in some localities, some households dry wild vegetables to ensure some supply during the dry season [52]. In this study, participants (83% and 62%) perceive wild fruits and wild vegetables consumption to be in decline, respectively. This is mainly because of shortage of rainfall (drought) which may temporarily affect the abundance of WEPs during that period. Similar findings were observed in several other studies about the impact of drought on the consumption of WEPs [10, 53]. Not only does this challenge threaten the abundance of these species but can also ultimately contribute to the loss of knowledge and people’s reduced reliance on them [4, 18].

The relationship between knowledge and consumption

This study found significant correlation between individuals’ ethnobotanical knowledge (no. of species) and consumption, despite some studies showing no correlation between the two variables [25]. There was a correlation between knowledge and consumption of both wild fruits and vegetables; there was also positive correlation of knowledge and consumption by gender and age groups, except for the youth. This result also supports the study’s hypothesis that there would be a positive relation between the number of WEPs species known and species consumed. This means that the higher the level of knowledge, the higher the diversity of species consumed or vice versa. Ladio & Lozada [25] showed that people know significantly more species than they consume. Indeed, this was the case in this study as there were more species listed than were consumed. From 24 listed wild fruit species, 20 (83%) were consumed and 16 (88%) out of 18 wild vegetable species were consumed. A good example is Ximenia caffra, which was one of the most frequently listed species, but was among the least consumed. According to Ladio & Lozada [25] the relationship between knowledge and consumption is linked to ecological conditions of gathering environments. If gathering environments are depleted or eroded because of climatic (droughts) or environmental conditions such as intensive land use or overharvesting, consumption of species may decline or cease, even though knowledge persists for some time.

Additionally, Reyes-Garcia et al. [24] attributed the relationship between consumption and knowledge to socio-economic factors such as location of the villages and how integrated the communities are to the market economy. They found that communities that were scattered and with less access to markets knew more and consumed more wild plant species [24]. They concluded that rapid socio-economic change will widen the gap between indigenous people and the use of traditional plants [24, 44]. Villages from this current study are also undergoing socio-economic change characterised by a modernising youth and the infiltration of retail markets in to rural localities [54]. Effects of these changes are visible judging by the youth’s low interest in consuming WEPs. One can only wonder what this disinterest would mean for future knowledge and consumption of WEPs.

Knowledge, consumption of WEP, and livelihoods

Indigenous knowledge and consumption of WEPs are important contributors to the sustainability of livelihoods [55]. Indigenous knowledge of WEPs contributes to human capital which is one of the livelihood assets important for the pursuit and attainment of livelihood objectives. Human capital is defined as the skills, knowledge, ability to labour, and good health which in conjunction enables people to participate in different livelihood activities [56]. Indigenous knowledge includes a range of resources on rural livelihoods are based such as crop production, range management, and wild plants [55]. With this knowledge, participant can identify which wild plant species to consume, when plants are available for collection, where, and how to prepare meals using those plants. Consumption of WEPs contributes to improved food security, income, reduced vulnerability to hunger, and acts as a safety net for shocks. The loss of this knowledge as an asset can have negative implication for the future of rural livelihoods.

Conclusion

This study has shown that people in the study area still know a substantial number of wild fruit and vegetable species and these foods still form an important part of the rural diet, as was hypothesised. Participants still have access to some of the species from their home gardens and in the surrounding fields. This study also found that knowledge about WEPs is produced and transmitted across and between people of different ages and genders in a variety of ways. This continuing transmission demonstrates how knowledge about WEPs is ongoing as both the young and old have reported to have learnt something new about WEPs recently. Even though that is the case, there continues to be concerns regarding the youth and their lack of interest in knowing and consuming WEPs. This disinterest could lead to the future loss of traditional plant knowledge. If, indeed, acquiring knowledge of WEPs is a lifelong process that changes in levels overtime [24], perhaps the youth are in their preliminary stages of knowledge acquisition. However, to ensure future preservation of WEPs knowledge, certain measures could be considered. Firstly, WEPs could be incorporated into modern recipes and meals; secondly, there should be formalisation of indigenous knowledge by increasing content in local libraries and in the school curriculum [24]. Youth development can focus on establishing an industry of eco-entrepreneurs who specialise in selling products made from WEPs [57]. The presence of WEPs needs to be increased in the media (social media, print media, and televisions programmes) and through development of indigenous plant identification applications. This could be a focus of national heritage programmes, such as national heritage week in September each year. These measures could contribute to the future conservation of WEP knowledge, especially among the youth. Longitudinal studies are required to investigate changes in levels of knowledge in the youth to evaluate the impact of biophysical, socio-economic factors, or intervention measures on knowledge and consumption of WEPs.