Socio-economic characteristics of the participants
Table 1 shows the demographic characteristics of the participants. Of the one hundred and forty seven participants, 68.7% were female and 31.3% were male. Their ages ranged from 16 to 87 years, with 52 years as the median. Most (78.9%) of the participants were heading households. The majority of participants were married (69.4%), 17% widowed, 8.8% single and 4.8% divorced (Table 1). The majority of households (64.6%) comprised between 5 and 8 family members, while 22.4% comprised 1 to 4 family members and 12.9% had more than 9 family members (Table 1). The majority (66%) of the participants were educated up to primary level, while 19.7% had attained secondary education, 12.2% were illiterate and 2% had attained tertiary education. More than three quarters of the participants (85%) were unemployed, surviving on less than $100 a month (Table 1). A very small proportion of the participants had constant income as civil servants (2%) and pensioners (4.1%) and their income was more than $150 a month (Table 1).
Diversity of edible weeds
A total of 21 edible weeds belonging to 11 families and 15 genera were identified in Shurugwi District, Zimbabwe (Table 2). These findings compare favourably with 19 edible weeds recorded in Hondey Valley, eastern Zimbabwe . A large number of edible weeds in the current study (16, 76.2%) are from 6 families (Table 3). Plant families with the highest number of edible weeds were: Amaranthaceae (4 species), Asteraceae and Tiliaceae (3 species each), Capparaceae, Cucurbitaceae and Solanaceae (2 species each). The genera with the highest number of edible weeds were Amaranthus and Corchorus with three species each, Cleome and Cucumis with two species each. Family Asteraceae is among the largest plant families worldwide and is known to contribute most of the agricultural and environmental weeds . Similarly, previous research by Drummond  and Wild  showed that a number of species belonging to Asteraceae, Amaranthaceae, Caryophyllaceae, Chenopodiaceae and Solanaceae were among the common weeds of agroecosystems in Zimbabwe. Heywood  examined the patterns and extent of invasions by agricultural weeds and concluded that most weeds come from the largest plant families like the Asteraceae and Poaceae.
Of the documented edible weeds, 52.4% are indigenous while 47.6% are exotic to Zimbabwe. With the exception of Cucumis metuliferus and Moringa oleifera which are semi-cultivated, the rest are categorized as agricultural weeds [22, 28, 30]. These edible weedy plant species grow naturally in farmlands, abandoned gardens, homesteads and many other ecological areas where they usually occur as weeds and can exist independently of direct human action. They may be harvested from the wild or from fallow and cultivated fields, or they may be cultivated. Similarly, the majority of traditional vegetables in Kenya exist as weeds of agriculture and are procured from the bushland and previously cultivated farmlands where they are communally gathered, and a few grow in kitchen gardens and along the lakeshores .
Interviews with participants revealed that the majority of edible weeds mature quickly and were collected during rainy and harvest season (Table 2). Only four species (19%): Cleome gynandra, Cucumis anguria, Cucumis metuliferus and Moringa oleifera were also available during the dry season, enabling households to obtain food in different times of the year (Table 2). These four species are domesticated or tolerated in home gardens. According to participants, Cleome gynandra, Cucumis anguria and Cucumis metuliferus are deliberately spared during digging, weeding and land clearing activities for the benefits or usefulness they provide to households as traditional vegetables. These species were available during the dry season because the leaves of Cleome gynandra and Cucumis anguria were preserved for latter use by sun drying (Table 2). Ripe fruits of Cucumis metuliferus were stored for 1 to 3 months in shade without any treatment. These preservation procedures extended the shelf-life of the edible parts of weedy plants. According to participants, preserved edible weeds formed an important component of the food resources in dry season when they were out of season and during drought periods. Similar results were obtained by Shava et al. , who found sun drying to be an important food preservation procedure, allowing rural communities to fill the food gap during periods of scarcity, particularly in the cold and dry winter season. During such periods of food shortage, traditional vegetables previously preserved by drying become very important in household food security. Research by Mnzava  showed that preservation of edible leaves is one of the strategies developed to help face times of food shortages.
Among the main uses of edible weeds were leafy vegetables (81%), followed by edible fruits (19%), edible corms (9.5%), edible flowers and seeds (4.8% each) (Figure 2). The vegetable dishes were prepared mainly as relish which accompanied maize, millet and sorghum porridge. Young leaves and shoots were boiled with salt and fried in cooking oil with other ingredients such as tomatoes and onions. Peanut butter was sometimes used instead of cooking oil. Corchorus tridens was cooked with bicarbonate soda or ash to lessen the mucilaginous state of the dishes. When the participants were asked to rate the importance of the species used, the most important edible weeds were Cleome gynandra, cited by 93.9% of the participants, Cucumis metuliferus (90.5%), Cucumis anguria (87.8%), Corchorus tridens (50.3%) and Amaranthus hybridus (39.5%) (Table 2). However, the most frequently used edible weeds in Hondey Valley, eastern Zimbabwe were Bidens pilosa, Galinsoga parviflora and Commelina zambesica. Commelina zambesica was not among edible weeds documented in Shurugwi District, while Bidens pilosa and Galinsoga parviflora were characterized by low frequency of consumption (Table 2).
These five edible weeds that are regarded as important in Shurugwi District are given special attention and their nutritional value is presented in Table 4. These edible weeds are important sources of macro and micro nutrients which are important for the maintenance of good health and prevention of diseases. The calorific value of 17–308 kcal of the edible weeds (Table 4) compare favourably to 23–84 reported in some South African traditional leafy vegetables ; and vegetables in general are known to have low energy values . The protein content of edible weeds (Table 4) is also higher than the protein content of some commercial vegetables [33, 35]. Table 4 shows a carbohydrate content range of 2.2-75 g. Only Cucumis anguria has a carbohydrate content lower than the 2.65-12.8 g carbohydrate range reported in some South African traditional leafy vegetables . All the five edible weeds have high levels of minerals in comparison to those available in the published literature. For example, only Cucumis anguria has calcium content lower than the daily requirement of calcium of 260 mg/day . These substantial amounts of minerals, trace elements and vitamins in the five edible weeds represent potential sources of critical nutrients in the diets of the local community. Previous research by , provided evidence that traditional leafy vegetables in South Africa mainly collected from the wild, which do not require formal cultivation could be important contributors to improving the nutritional content of children and other vulnerable groups.
The remainder of the edible weeds were characterized by low frequency of consumption (Table 2). These included Amaranthus spinosus (8.8%), Amaranthus thunbergii (12.2%), Bidens pilosa (6.1%), Celosia trigyna (16.3%), Chenopodium album (23.8%), Cleome monophylla (25.9%), Corchorus asplenifolius (6.8%), Corchorus olitorius (4.8%), Cyperus esculentus (10.2%), Galinsoga parviflora (7.5%), Hibiscus articulatus (11.6%), Moringa oleifera (8.2%), Oxalis latifolia (9.5%), Physalis angulata (10.9%), Solanum nigrum (13.6%) and Sonchus oleraceus (2.7%). The low frequency of consumption was mainly due to their taste, which was said to be bitter and somewhat discouraging. Similar results were obtained by Łuczaj [47, 48] who documented a decline in the use of wild green vegetables in Poland; used mainly in times of food scarcity. The reasons interviewees gave for the continued consumption of these edible weeds in Shurugwi Distict included economics and lack of alternatives. Harvesting of edible weeds in Shurugwi District, Zimbabwe is driven by the fundamental concern to secure food. In this context, the interest in edible weeds is therefore, to mitigate the consequences of insufficient agricultural production. The majority of these edible weeds characterized by low consumption frequency are collectively referred to as “poor man’s food” , because they are regarded as inferior and marginalized by the majority of people. Some of these traditional vegetables may be used both as food and medicine. Examples include Bidens pilosa and Moringa oleifera. Field interviews revealed that some people consume Bidens pilosa to ease their “high blood pressure” worries, stomach pains, oral thrush, to boost the immune system and rheumatism.
When preparing a Cleome gynandra dish, participants often added Amaranthus hybridus, Amaranthus spinosus, Amaranthus thunbergii, Chenopodium album and Cleome monophylla to increase bulk. Interviews with participants revealed that Cyperus esculentus, Oxalis latifolia and Physalis angulata were mainly collected and eaten by children. The corms of Cyperus esculentus and Oxalis latifolia were eaten raw, excluding the peel of the underground parts. Previous research by Campbell  and Campbell et al.  showed that this opportunistic collection was done by children while undertaking activities such as firewood gathering or water collection.
The importance of edible weeds for local livelihoods was ubiquitously perceived, with all participants reporting their contribution towards food security and nutrition (Table 5). About one fifth (21.1%) reported the importance of edible weeds as traditional medicines and 10.2% reported the contribution of edible weeds towards reduction of poverty levels and food inequalities. A smaller proportion of the participants, 8.2% and 2% reported that edible weeds were sold on local markets to supplement family’s income and exchanged with other goods and services respectively (Table 5). Although perceptions on the actual benefits derived from the collection and management of edible weeds in Shurugwi District were variable among the participants (Table 5), there is no doubt that this category of plant resources is important in meeting household food needs and food security (Table 5).