Adequate knowledge on the use of high-value vegetables is key to achieving the nutritional, medicinal, and socio-economic needs of the communities. The information serves in devising strategies for promoting the cultivation, consumption, processing, storage, and commercialization of these high-value vegetable species, thus potentially contributing to improving the nutritional and health needs, living standards, and expansion of vegetable markets and employment [1
]. The information is particularly significant for smallholder farmers of sub-Saharan Africa (SSA), whose diets are dominated by carbohydrates and often lack vitamins and minerals. These farmers face challenges in participating in high-value foods at a global level, leading to changing focus towards promoting nutraceutical and insecticidal indigenous vegetables [1
] than the exotic vegetables.
Spider plants (Gynandropsis gynandra
, L. Briq.) have a potentially critical role in food, nutrition, and generation of income amongst the rural households yet it continues to be neglected and underutilized. In several parts of the SSA, spider plants grow naturally in the wild and in farmers’ fields during the rainy season [7
]. Tender leaves, stems, pods, and flowers are consumed as vegetables by boiling in water or milk, with or without mixing with other vegetables [9
]. Furthermore, the initial cooking water may be decanted, and fresh boiling water added to reduce the bitter taste particularly in purple stemmed accessions. The draining of water during cooking might, however, reduce the quantities of water-soluble micronutrients, such as vitamin A and C. Nevertheless, when compared with other vegetables, Silue [10
] observed that spider plants best retain vitamin C after cooking.
In Benin, spider plants are used as a nutraceutical and medico-magic protection amongst different sociolinguistic groups [11
]. In some areas, such as Kenya and South Africa, seed companies sell the seed of spider plants to farmers who either establish it in the field as a vegetable or plant it in association with other crops. Namibia, on the other hand, depends on South Africa for the supply of seeds but unfortunately, spider plants are not amongst the traded seeds. Studies show that spider plants grow naturally around the country, mostly in North Central and North Eastern Namibia, which consist of the regions of Kunene, Okavango East and West, Ohangwena, Omusati, Oshana, Oshikoto, and Zambezi regions [12
]. The vegetable is known by several names in Namibia, ranging from spider flower to cat’s whiskers in English, Ombidi in Oshikwanyama, Omboga in Oshindonga, Ombowa yozongombe or Ombowayozondu in Herero, and Gomabeb in the Damara languages [12
]. No studies, however, have been reported aimed at exploring how the rural people use the species. A few related studies have been conducted on indigenous fruits [13
], medicinal plant use by traditional healers [14
], and medicinal properties of Ximenia
]. The lack of research has perpetuated the underestimation and under-exploitation of the potential value of the vegetable, hence denying the rural households from optimizing its potential benefits. Challenges limiting the production of spider plants include lack of information on agronomic practices, limited variety development, dwindling knowledge of the species (especially amongst the younger generations), poor seed germination, and inadequate extension services [4
Dansi et al. [18
] acclaimed that ethnobotanical study aimed at evaluating, identifying, documenting, and prioritizing the interventions could have the potential to reduce production constraints and improve agronomic practices. In addition, the study could also aid in assessing the contribution of the vegetables to household income. There has been limited ethnobotanical studies, however, aimed at exploring how farming communities and consumers of different sociolinguistic groups utilize spider plants. For example, Sogbohossou et al. [4
] provide some insights on how sociolinguistic groups of Benin and Togo utilize the species, but similar studies are lacking in Southern Africa. According to Martin [19
], ethnobotany refers to “the interactions between people and plants,” which impacts on utilization. Studies aimed at establishing the levels of utilization of G. gynandra
suggested that smallholder farmers select the vegetable based on production traits and nutrient quality [20
]. As a result of different degrees of selection, agro-morphological diversity [21
] is created. In Namibia, spider plants are commonly seen being sold in open markets and used during different traditional ceremonies, such as Olufuko. However, no study has been conducted to determine the extent of use of the species amongst farming communities and consumers.
It is against this background that the study was conducted to (1) identify the uses and utilization traits of spider plants amongst the farming communities and consumers; and (2) determine the level of consensus and rank utilization traits of spider plants amongst the farming households and consumers in the five regions of northern Namibia. In this study, a farming household refers to individuals living in the same house and primarily depending on farming as a source of livelihood. Furthermore, consumers referred to individuals who paid some amount of money to acquire vegetables at the open markets. It was assumed that consumers played important roles in influencing decisions at farm level hence affecting the agro-economic system. Rohm et al. [22
] suggested that the behavior of people in the utilization of food, including vegetables, is shaped by health, supply, and culture and family habits which are inherited from generation to generation. It was, therefore, hypothesized that belonging to different user groups (farming households or consumers), sociolinguistic groups, regions, gender and age groups, and those of different education levels does not affect the utilization of spider plants.
The extent of utilization of vegetable species is believed to be shaped by cultural beliefs or ethnicity [27
], norms [33
], geographical location [34
], and availability of the species. The multiple utilization traits and perceived nutritional and medicinal benefits of spider plants amongst farming households and consumers of different sociolinguistic groups implied the cultural significance of the vegetable and the potential for domestication in northern Namibia. The medicinal and nutritional utilization traits of spider plants identified in this research were consistent with the findings of other researchers [36
] who reported nutritional properties which were believed to heal eyesight, and cure marasmus and scurvy. Furthermore, researchers [2
] reported the major use of spider plants as food and medicine, with 80% and 40% of the respondents, respectively. The use of the vegetable for income generation was third, with 20% of respondents, while the use for cultural reasons was the least (5% of respondents) [2
]. Kolbeg [12
], citing Kakujaha-Matundu [37
], reported income of N$
1131.36 per season per household in Namibia, while in South Africa [38
], researchers reported average income of R413 per month. Their findings, however, put less emphasis on social use, which was contrary to the finding of this study. Differences in cultural values and beliefs might explain the differences in spider plants use across sociolinguistic groups. The strong link on the use of spider plants in social ceremonies in northern Namibia was supported by the vegetable’s historical perspective in other countries, such as Kenya and Uganda, where the vegetable was used to service chiefs and important people in the society [39
]. In addition, a study conducted in Kenya [16
] reported that the vegetable was used to serve high profile visitors to signify respect amongst the Luo and Kisii communities, thus agreeing with the findings of this study. In Namibia, the leaves of spider plants are sometimes mixed with other species, such as Amaranthus
spp., for consumption. Oftentimes, cooked leaves are dried into cakes locally known as “omavanda” which are flattened and either stored for consumption during the months of scarcity or for sale at the open markets [12
]. These findings suggested that spider plants were important to the social and cultural systems of the sociolinguistic groups of northern Namibia; as such, its reducing trends in diversity [40
] might likely lead to undesirable impacts on the cultural identity and stability of these sociolinguistic groups, as observed by other researchers [41
]. The vegetable could, therefore, be classified as a cultural keystone species [43
], according to theories and major hypotheses in ethnobotany. The differences and similarities observed across the sociolinguistic groups, however, call for an in-depth study of the specific cultural differences that might be responsible for the similarities and differences. We found, in this study, that leaves were the main component of the plant used, but we do not have evidence of the factors that might have influenced the choice of the plant part.
The three clusters related to the ranking of the uses of spider plants suggested that sociolinguistic groups close to each other were more likely to rank the utilization traits in a similar way, which could imply that the clustered groups shared similar cultural beliefs. This observation is consistent with the findings of other researchers [44
], who found that traditional knowledge on the use of indigenous vegetables was more likely to be passed on amongst relations. In this study, sociolinguistic groups from Omusati formed the first cluster, Ohangwena, Oshana and Oshikoto formed the second cluster, while the third cluster comprised sociolinguistic groups from Okavango West. The clusters were consistent with the geographical location of the regions, whereby Omusati is in the northwest, and Ohangwena, Oshana, and Oshikoto shared boundaries in the north-central area, while Okavango is located far north-east. Researchers [35
] reported differences in the importance and uses of vegetables across regions and communities and attributed the differences to cultural influence, tradition, geographical separation, and biology. For example, researchers in Benin [34
] observed that geographic region was a strong determinant of the use of traditional vegetables. However, Powell and other researchers [35
] identified significant variation in knowledge and use both between the geographical regions and between socio-linguistic groups within the regions. In addition, a study on the use of Strychnos spinosa
] identified climatic zone and sex as general factors influencing the choice of the use categories of the species. These observations could be applied to the case of northern Namibia, where the study regions were geographically separated and had unique sociolinguistic groups which could imply cultural differences playing the role as well.
Furthermore, women were found to value sociocultural uses of spider plants more than men and this could have been influenced by differences in local knowledge distribution between the gender groups, as suggested by Pfeiffer and Butz [47
]. According to researchers [48
], rural women are usually unemployed and tend to combine sociocultural information as they discharge household and subsistence activities. This tends to give women an edge over men on the knowledge of sociocultural values. The positive association between age and socio-cultural use of spider plants, with the older people considering socio-cultural uses as more important than the younger generations, would suggest erosion of cultural values amongst the young generation.
Moreover, other researchers [49
] reported that the differences in cultural influence, tradition, geographical separation, and biology could account for the shaping of the agro-morphological diversity of the species. Furthermore, the existence of strong culture, tradition, and gender [49
] was reported to have an influence on the utilization of indigenous crop species. These findings underscore the importance of considering a range of factors in each geographical region, in order to identify and determine the relative contribution of each factor on the differences in utilization of traditional vegetables. In this study, however, gender did not influence the ranking of the utilization traits. The findings, therefore, called for an adequate understanding of cultural norms, tradition, and gender in influencing utilization of spider plants to shape future attempts in popularizing the vegetable. Voster, et al. [50
] reported organoleptic quality as one of the factors influencing the use and preference of vegetables across age and gender groups. In addition, the follow-up studies would also aid in determining the Cultural Food Significance Index (CFSI) [49
], in relation to other vegetables and across the different sociolinguistic groups.
Finally, the study found that farmers were knowledgeable that spider plants had nutritional and medicinal attributes. This finding was consistent with other researchers [51
], who confirmed that several underutilized crops were nutrient-dense. Nutrient density of the underutilized crops offers an opportunity to enhance access to diversified diets amongst the rural households, which remains a challenge particularly in SSA, including Namibia. The respondents perceived that the nutritional value of spider plants superseded all other indigenous vegetables, hence putting it at the advantage of being widely domesticated and adopted. Other researchers considered a diversification of the diets using indigenous vegetables, such as spider plants, as cost-effective and sustainable in alleviating malnutrition for the households living below the poverty line [53
]. The nutritional and medicinal attributes [52
], therefore, make the spider plant an ideal vegetable for its inclusion in healthy diets and the promotion of food and nutritional security. The research provided a good understanding of the uses and utilization traits of spider plants, including the influence of sociocultural factors. These provided insights towards sustainably, popularizing the domestication of spider plants amongst the farming communities of northern Namibia. The rolling-out of a robust and demand-led breeding program aimed at developing production technologies that would ease production changes constitutes the first step. The breeding program should capitalize on the nutritional value of the plant, organoleptic quality, and cultural customs which generate utilization habits from generation to generation, as observed by Nemeth et al. [54