A total of 137 Zhuang respondents were selected for interviews, including 57 from Shangsi County, 39 from Fangcheng District, 15 from Dongxing City, and 26 from Gangkou District. Among these respondents, 67 were male, while 70 were female. The age of the respondents ranged from 17 to 94, with the majority falling within the 30–60 age group (Table 1). The informants had diverse occupations, including farmers, wage workers, and traders, with farmers being the most prominent group. They reported a total of 163 Wild Edible Plants (WEPs), and detailed ethnobotanical information about these plants is provided in Table 2. This information includes the scientific name, vernacular name, Chinese name, family, habit, food category, used part, mode of consumption, collection season, recipe, specimen number, and CFSI.

These species belong to 67 botanical families, of which the largest are Asteraceae (14 species), Fabaceae (11), Poaceae (7) and Rosaceae (7) (Fig. 2a). There are 35 families with only one species. The habitats of these WEPs are mostly herb (74) followed by trees (30), shrubs (27), Liana (16), Shrub or Dungarunga (11) and Bamboo (5) (Fig. 2b). Local consumption of rare and endangered plants is not common, with three species classified as “Endangered” and three more categorized as “Vulnerable”, while the remaining species are considered “Least Concern”. Furthermore, it is worth noting that 17 of these wild edible plant species are non-native, as indicated by asterisks in Table 2. Out of these, seven species have been identified as invasive alien species.

a Family distribution of WEPs species of angiosperm category; b Habitats of WEPs used by Zhuang people

Wild vegetables and tea substitutes are two main categories of WEPs (Fig. 3). All WEPs are typically consumed in the form of stir-fried dishes, boiled items, soups, served cold, and dressed in sauces. Plants have edible parts, such as stems, leaves, fruits, seeds, flowers, roots, and tubers. Among them, the most commonly consumed parts are fruits (37, 22.7%), followed by whole plants (33, 20.2%) and leaves (21, 12.9%) (Fig. 4). The availability of wild edible plants remains high throughout the year, with peak seasons in August (101) and October (101), followed closely by July (98) and November (96). The lowest abundance is observed in January (75), with a difference of 26 plant species compared to the highest abundance in August and October. Therefore, the period from July to November is considered the most suitable for consumption of wild edible plants in Fangchenggang. During this time, the market also offers the widest variety of plant species for sale (Fig. 5).

Main food categories of WEPs used by Zhuang people (Abbreviations in this figure are the same as those in Table 2)

Main edible parts of WEPs used by Zhuang people

Months of collecting WEPs

Wild vegetables were the most extensively utilized food category, comprising 53 edible species. Additionally, there were ten plants that served as both vegetables and tea substitutes, five species that functioned as both vegetables and spices, one plant that served as both a vegetable and a nut, and one plant that served as both a vegetable and a fruit, making a total of 69 species belonging to 40 families. The primary edible parts of wild vegetables are the whole plant (34), tender branches and leaves (21). They are commonly consumed in diverse forms such as salads (after treatment), cooking in hot water, or stir-frying. Additionally, they are used as ingredients in soups or when stewed with pork or chicken. It is not common to consume wild raw vegetables without pre-treatment (Fig. 6).

Some wild vegetables in the study area [(1) Plantago asiatica; (2) Portulaca oleracea; (3) Emilia sonchifolia; (4) Toona sinensis; (5) Oenanthe javanica; 6.Houttuynia cordata]

Wild vegetables are typically priced slightly higher than conventional vegetables, such as Pentaphragma spicatum, which is an endemic species of China and belongs to the family Pentaphragmataceae. This plant species is found exclusively in southern Guangxi, including Shiwan Mountains, Dongxing, Fangcheng, Daxin, Xinyi in Guangdong, and Baisha and Baoting on Hainan Island [34]. It thrives in the dense forests of tropical valleys. Prior to this research study, there were no reports on the edibility of this plant. However, in Shangsi, local residents refer to this plant as a “jade vegetable” due to its jade-like edible leaves. The leaves can be picked and stored for up to a month without deterioration and can be stir-fried or used in soups. At the tourist restaurant of Shanwan Mountains in Shangsi County, there is a special dish called “Stir-Fried Jade Vegetable” served to visitors. The best taste of P. spicatum, nurtured by Shiwan Mountains, is achieved when it is stir-fried. Its flesh-like leaves are crisp and fragrant. The villagers who collected P. spicatum shared with us that consuming this plant can serve as a natural source of iron. Additionally, they mentioned that boiling the whole plant in water and using the resulting infusion externally may be effective in treating rheumatism, bruises, promoting blood circulation, and alleviating blood stasis [35]. The local residents near Shiwan Mountains are familiar with this plant and know precisely where it grows. However, due to the high environmental requirements of P. spicatum, villagers have been unsuccessful in transplanting it to their courtyards despite various attempts.

Consequently, the limited utilization of P. spicatum as a source of domesticated species and valuable genetic resources for developing new crops through hybrid screening naturally [36] results in higher prices (Fig. 7).

The habitat of Pentaphragma spicatum and dishes made from it

Tea substitutes are the second largest food category of wild edible plants (WEPs) used by the Zhuang people, consisting of 42 species. Among them, 10 species serve as both wild vegetables and tea substitutes, while 3 species serve as both oils and fats and tea substitutes. The whole plants (21) of wild species are the most commonly used part, followed by the leaves (19). The usual method of preparation involves boiling in water or steeping in hot water. The tea substitute plants in the Fangchenggang region can be classified into two main types based on their different uses: Liáng chá and flavor-enhancing tea substitutes. There are 27 plant species such as Sarcandra glabra, Centella asiatica, and Gynostemma pentaphyllum, which are used by local residents as Liáng chá to cope with hot weather. Another 15 species like Camellia petelotii, Camellia euphlebia, and Helixanthera parasitica are chosen by Zhuang people living in remote areas when tea is not readily available, in order to enhance the flavor by steeping these plants (Fig. 8).

Some Liáng chá plants in the study area [(1) Lophatherum gracile; (2) Murdannia bracteata; (3) Artemisia indica; (4) Osbeckia chinensis; (5) Striga asiatica; (6) Imperata cylindrica]

In eight different markets, a total of 24 vendors offer both fresh and dried Liáng chá plants. These vendors are distributed as follows: 6 in Shangsi County, 9 in Fangcheng District, 5 in Gangkou District, and 4 in Dongxing City. Customers have the flexibility to purchase specific plant species or opt for pre-mixed blends of Liáng chá. Sarcandra glabra, Centella asiatica, and Gynostemma pentaphyllum are the most commonly available plants used for making Liáng chá. Similar findings can also be found in the "Ethnobotanical study on herbal tea drinks in Guangxi, China” [37].

Some vendors prepare Centella asiatica with added sugar to create a refreshing tea beverage, which is sold at a price of 10 yuan per cup. Moreover, they also boil Abrus pulchellus, Grona styracifolia, Siraitia grosvenorii (cultivated, not listed in the inventory), Lonicera japonica (cultivated, not listed in the inventory), and Hedyotis effusa mixed with sugar to create a tea drink known as “Xia huo cha”, which helps to cool down the body. The price of this beverage is the same as that of Centella asiatica.

Ilex confertiflora, known as “Qingming tea” among the Zhuang people in Shangsi County, is a highly regarded tea substitute plant traditionally harvested during the Qingming Festival. Interviewees have praised its exceptional taste, with a TSAI score of 9.0. However, in recent times, many younger individuals have migrated for employment opportunities, making them less inclined to invest their time in gathering and processing these plants in mountainous areas. Consequently, this traditional practice is primarily upheld by the older generations. Considering the plants in the Ilex genus of the Aquifoliaceae family often possess anti-inflammatory activities and other medicinal properties [38, 39], we interviewed 28 households and 71 individuals, with 56% of respondents stating that it has the effect of clearing heat and detoxification, 24% claiming it can lower blood pressure, and 20% being unsure about its specific effects. Further studies on its chemistry, biological activity, and toxicity are needed for potentially developing new tea substitute (Fig. 9).

Ilex confertiflora and Qingming tea

A total of 30 plant species are consumed as fruits. Among them, 3 species serve as both vegetables and fruits, while 1 species is considered both a nut and a fruit. The majority of the fruits we commonly consume in our daily lives are cultivated within the Rosaceae family [40]. Similarly, among the wild fruits surveyed, the Rosaceae family has the highest diversity of plant species, with many of them being shrubs that are easily gathered, such as Rubus leucanthus, Rubus cochinchinensis, and Rubus pluribracteatus. Many studies have revealed that wild fruits possess a higher nutritional value compared to cultivated fruits [41, 42]. Wild fruits are especially popular among children as they serve as a source of essential vitamins and minerals, particularly when cultivated fruits are not readily available. Additionally, Saurauia tristyla and Phyllanthus emblica are also commonly sold on the market (Fig. 10).

Some wild fruits in the study area [(1) Saurauia tristyla; (2) Garcinia oblongifolia; (3) Phyllanthus emblica; (4) Baccaurea ramiflora]

In addition to being consumed as fresh fruit, the wild fruits abundant in the area are traditionally fermented along with rice by the Zhuang people, such as Rhodomyrtus tomentosa, Rosa laevigata, Vitis balansana, and Ficus hirta, to produce a traditional alcoholic beverage known as “guo jiu”. This type of liquor typically has a lower alcohol content, usually around ten degrees. Local inhabitants believe that these beverages can promote blood circulation, stimulate metabolism, and have a beneficial effect on the body. Scientific research has also indicated that such as mature fresh fruits of Rosa laevigata contain high levels of vitamin C, reaching up to 1187.38 mg/100 g. Additionally, they have a total sugar content of 25.76%, with a reducing sugar content of 24.38% [43]. The fruit pulp contains 19 types of amino acids, including 8 essential amino acids for the human body. Transforming these fruits into alcoholic beverages can confer health benefits due to their nutritional composition [44].

While the variety of wild spice plants is not extensive, their frequency of use is remarkably high, with a total of 15 species. Among them, 6 plants serve as both wild vegetables (Wv) and spices (Sp), and 1 plant also functions as wild fruit (Wf). Most of these spice plants are well-suited to complement local cuisine's unique flavors, offering elements of acidity, umami, and taste enhancement (Fig. 11).

Stalls selling only spice plants

One particularly noteworthy combination of spices is used to make a dipping sauce for sashimi (thin slices of raw fish). It typically includes Piper sarmentosum, Persicaria viscosa, Perilla frutescens var. purpurascens, Houttuynia cordata, and Ocimum basilicum. This combination is commonly found in the market (there are 18 vendors in total), where vendors often sell these plants bundled together. It is rare to find them sold separately, and some stalls specialize exclusively in these spice plants, highlighting their importance in the local cuisine. In more remote villages located far from the city, people also prepare this delicacy during festivals and special occasions. Although the condiments used may not be as diverse as those in urban areas, Piper sarmentosum, Persicaria viscosa, Houttuynia cordata, and Ocimum basilicum are essential ingredients that can be easily collected.

The comparison results of the cultural food significance index (CFSI) of Zhuang edible wild plants in Fangchenggang are shown in Table 2. The edible wild plants in this area were clustered based on the CFSI, and those with broad application and high value, which played an important role in the local people's traditional diet, are highlighted. To classify the plants cited plants into four groups: species with very high significance (CFSI > 500), high significance (500 > CFSI ≥ 100), moderate significance (100 > CFSI ≥ 10), low significance (CFSI < 10).

In the very high significantcategory (CFSI > 500), there were a total of 15 plant species identified. Tea substitutes were the primary plants within this category, followed by vegetables. The notable plants in this category include Camellia oleifera, Plantago asiatica, Sarcandra glabra, Portulaca oleracea, Centella asiatica, Piper sarmentosum, and Elephantopus scaber. They are widely distributed in this area and are found almost everywhere.

Camellia oleifera, displaying the highest CFSI (The cultural food significance index) value, is extensively distributed in the Fangchenggang region. During periods of limited availability of edible oil, it has traditionally served as a source for oil extraction to meet daily dietary requirements. Contemporary scientific researches have revealed that C. oleifera oil possesses an unparalleled concentration of unsaturated fatty acids, ranging from 85 to 97%, thereby surpassing various other edible oils [45]. Its consumption has been linked to the effective prevention and treatment of cardiovascular and cerebrovascular ailments [46], leading to its recognition as the “oil of longevity”. Consequently, individuals persist in favoring C. oleifera oil due to its beneficial impact on health and its nutritional value.

A total of 53 plant species were classified in the high significant category (500 > CFSI ≥ 100). These species exhibit wide distribution in the area and offer a diverse range of fruits, vegetables, food dyes, snacks, and substitutes for tea to the local inhabitants. The relatively lower CFSI value of these plants is primarily attributed to factors such as the edible parts, taste, and the extent of domestication and cultivation carried out by the local residents. For instance, frequently encountered species like Basella alba, Ocimum basilicum, and Curcuma longa are predominantly cultivated, although not to the same extent as common staple vegetables. However, people also enjoy consuming them due to their high nutritional value [47].

Additionally, there are specific plants utilized for dyeing purposes, including Liquidambar formosana, Curcuma longa, Peristrophe japonica, and Asystasia nemorum. While these plants also hold significance in local wild vegetable consumption, they are predominantly associated with significant festivities and ceremonies rather than daily meals, such as the Dragon Boat Festival, Spring Festival, and weddings. Particularly on the third day of the third lunar month within the Zhuang ethnic group. Dyeing plants are indispensable components during these occasions [48]. The naturally occurring seasonal plants are utilized to dye glutinous rice into four colors: red, black, purple, and yellow. As glutinous rice is inherently white, only four types of dyeing plants are involved. Most Zhuang people used similar plant-based dyes (pigments), although slight variations may occur due to differences in the availability of plant resources in different regions. Additionally, the five-colored glutinous rice holds multiple significances, serving as both a festive delicacy and an offering to ancestors, symbolizing familial unity and harmony. The skill to make five-colored glutinous rice is possessed by every household, indicative of the widespread adoption and preservation of this culinary tradition [49]. Despite the time constraints faced by contemporary youth in preparing five-colored glutinous rice, they still purchase it from markets or restaurants. In comparison with other traditional cultural practices, the production and consumption of five-colored glutinous rice have been relatively well-maintained.

There were a total of 72 plant species classified in the moderate significant category (100 > CFSI ≥ 10). Herbaceous plants accounted for the highest number in this category. Moreover, several plants with medicinal properties were included, such as Bidens pilosa, and Garcinia oblongifolia and Cibotium barometz. In the low significant category (10 > CFSI), the number of plants was the lowest, with a total of 18 species. The plants in this category primarily consisted of species with special distribution areas, unappealing taste, or specific uses. An example of such a plant is Praxelis clematidea. In previous hard times, it was common to rely on this plant as a source of sustenance. However, with the availability of more options nowadays, it is frequently utilized as animal feed, particularly for pigs.