Diversity of wild edible plants

The variety of WEPs traditionally used by the Tujia ethnic group in Laifeng is abundant and diverse. Through extensive investigation and categorization, 163 different wild edible plants belonging to 64 families and 118 genera have been identified. Botanical and ethnobotanical information including family names, scientific names, Chinese names, habits, food categories, edible parts, consumption mode, collection months, multiple uses, FC, RFC, and CFSI is listed in Table 2. These WEPs comprise three groups: ferns (4 families and 4 species), gymnosperms (1 family and 1 species), and angiosperms (59 families and 158 species), with the angiosperms being the most plentiful. The families containing the most WEPs are Rosaceae (23), Poaceae (10), Asteraceae (10), Amaranthaceae (7), and Lamiaceae (7), accounting for 35.0% of the total number of species (Fig. 2a).

Table 2 Inventory of wild edible plants used by the Tujia ethnic group in LaifengFig. 2

Diversity of wild edible plants used by the Tujia ethnic group in Laifeng. a Family distribution; b habit distribution; c edible parts distribution; d collection months; e consumption mode distribution; f food category distribution

Categorized by their habits, the WEPs traditionally utilized by the Tujia ethnic group in Laifeng predominantly consist of herbs (69), comprising for 42.3% of the total. This is followed by shrubs (40, 24.5%), trees (24, 14.7%), and lianas (21, 12.9%). Bamboo plants are less common, with a total of 9 species (Fig. 2b). Due to their ease of harvesting, diverse variety, and broad distribution, herb plants are more frequently consumed than other habits.

The WEPs have also been categorized by their edible parts, yielding 16 categories including fruits, leaves, stems, aboveground parts, flowers, roots, seeds, rhizomes, the whole plant, etc. Fruits (68, 41.7%) are the most commonly consumed edible parts, followed by leaves (40, 24.5%) and stems (34, 20.9%) (Fig. 2c).

While the collection months may vary for different categories of WEPs, they are generally concentrated from March to October (Fig. 2d). The Tujia ethnic group in Laifeng prefer to collect tender stems and leaves of wild plants as vegetables for consumption, predominantly gathering wild vegetables from March to May in spring. Wild fruits and nuts have more variety, with the greatest collection occurring in summer and autumn from July to October, during which mature fruits and seeds are more abundant.

Owing to the diversity WEPs and dietary habits, various consumption modes are employed. There are 15 consumption modes for WEPs, including being eaten raw, stir-fried, boiled, stewing with meat, soaking in wine, used as spices, and cold and dressed with sauce, etc. Eaten raw is the most common method, with a total of 63 species, accounting for 38.7%, followed by stir-fried (49) and boiled (31) (Fig. 2e).

Classification of wild edible plants

Based on the diverse purpose of consumption, the WEPs can be categorized into 9 distinct groups: vegetables, fruits, wine-soaking plants, spices, food substitutes, tea substitutes, nuts, coagulants, and oil. Among these, wild vegetables (78) and wild fruits (52) constitute the majority, accounting for 79.8% of the total species (Fig. 2f). This is followed by wine-soaking plants (12) and spices (11), as along with food substitutes (9), tea substitutes (6), nuts (5), and coagulants (2). Oil use is the least category, with only 1 species.

Wild vegetables

A total of 78 types of wild vegetables are traditionally utilized by the Tujia ethnic group in Laifeng, primarily cinsisting of leaves, stems, and aboveground parts. These are principally processed using methods such as stir-frying, boiling, and stewing with meat. The most frequently mentioned ones are Allium macrostemon, Houttuynia cordata, Pseudognaphalium affine, and Artemisia indica. A macrostemon is a wild vegetable universally consumed by households of the Tujia ethnic group in Laifeng. It is typically served as a cold or pickled vegetable and can also be employed as a spice (Fig. 3a, b). A macrostemon is widely distributed in Laifeng County and is also cultivated in some Tujia courtyards as a supplement to Allium fistulosum, which is the principal spice. According to the Tujia ethnic group in Laifeng, A macrostemon possesses a more potent aroma and certain medicinal properties, rendering it beneficial as a vegetable and spice.

Fig. 3

WEPs used as vegetables. a Allium macrostemon being dried; b Allium macrostemon and Pteridium revolutum being sold; c Houttuynia cordata; d Artemisia indica; e Pseudognaphalium affine; f Make Artemisia indica and Pseudognaphalium affine cakes; g Artemisia lancea; h she Fan; i process Artemisia lancea

Houttuynia cordata is a medicinal and edible plant deeply cherished by the Tujia ethnic group in Laifeng. Every spring, as the temperature rises and new leaves sprout from the roots of H cordata, it is an optimal time to consume its tender roots and stems. Contrarily to the practice in Yunnan and Guizhou where the entire H cordata is consumed, the Tujia ethnic group in Laifeng restrict their consumption to the tender roots and stems, served cold and dressed with sauce. The above ground parts are more commonly utilized as herbal medicine to treat colds. In the local market town of Laifeng in spring, it is common to see vendors selling washed or pickled H cordata roots (Fig. 3c).

Pseudognaphalium affine and Artemisia indica are frequently used by the Tujia ethnic group in Laifeng to prepare glutinous rice cakes (Fig. 3d–f). In March and April, the Tujia ethnic group in Laifeng gathers the tender stems and leaves of P affine and A indica, processes them to removes their bitterness through hammering, kneading, and washing, and then mixes them with glutinous rice flour to produce cakes. These cakes are filled with ingredients such as bacon, Allium macrostemon, Allium sativum, dried tofu, and peppers, and are covered with leaves of Citrus sinensis. Cakes sold in the market town are typically made by combining P affine and A indica. Using only P affine results in softer cakes that are less easy to shape, while using A indica alone gives the cakes a darker color. The perfect blend of P affine and A indica results in cakes with a harmonious balance of color, aroma, and taste. Apart from P affine and A indica, Artemisia lancea, also known as “bitter Artemisia” by locals, is often used to prepare Shefan, a meal made by steaming a mixture of A lancea and glutinous rice (Fig. 3g–i).

Wild fruits

A total of 52 wild fruits are utilized for consumption by the Tujia ethnic group in Laifeng, typically eaten raw or employed for fruit wine production. The most popular ones include Hovenia acerba, Rosa laevigata, and Rosa roxburghii f. normalis. H acerba is consumed in the form of mature fruit stalks. In addition to eat it raw, the Tujia ethnic group in Laifeng also soaks it in wine, positing that the H acerba wine can alleviate weakness and cramps in the hands and feet (Fig. 4a). Studies have indicated that the extract from the stem of H acerba possesses robust antioxidant activity [45].

Fig. 4

WEPs used as fruits. a Hovenia acerba wine; b Rosa laevigata wine; c Rosa roxburghii f. normalis wine; d Rosa laevigata; e Rosa roxburghii f. normalis; f Rubus corchorifolius; g Rubus coreanus; h Rubus setchuenensis; i galls on Camellia oleifera

Rosa laevigata and Rosa roxburghii f. normalis are colloquially referred to as “sugar jars” and “prickly fruit,” respectively. They are both shrubs of the Rosaceae family and can also be soaked in wine for consumption apart from being eaten raw (Fig. 4b–e). These two WEPs typically flourish near rivers and ditches. However, their populations have largely diminished due to the construction of production and living infrastructure, as well as resent environmental damage.

Further, Rubus sp. are also cherished wild fruits of the Tujia ethnic group in Laifeng. Rubus corchorifolius, R rosifolius, R coreanus, and R setchuenensis are frequently mentioned and highly favored for their taste (Fig. 4f–h). In the case of Camellia oleifera, galls derived from its fruits and leaves are consumed. During periods of food scarcity, these are also stir-fried to alleviate hunger (Fig. 4i).

Spices

Spice plants, encompassing a total of 11 wild species, feature prominently in the diet of the Tujia ethnic group in Laifeng. The Tujia ethnic group in Laifeng favors the consumption of the unripe, tender fruits of Litsea mollis, harvested from May to July. Following harvesting, it is immersed in oil and vinegar and consumed as a spice (Fig. 5a-b). Certain varieties of spices are cultivated in homegardens for convenient harvesting and use. The leaves of Perilla frutescens and Perilla frutescens var. crispa are frequently used to cook fish to eliminate the fishy smell (Fig. 5c). The leaves of Acorus gramineus are employed for stewing meat to enhance its aroma (Fig. 5d). The fruits of Hedychium coronarium are used for stewing chicken, the flowers are used for crafting oil tea soup, and the rhizomes are stir-fried. Heptapleurum delavayi, colloquially termed “fermented soybean leaf,” is favored by housewives, but is not directly utilized as a spice (Fig. 5e). Rather, it serves as a bedding to augment the aroma of fermented soybean during its production.

Fig. 5

WEPs used as spices, food substitutes and tea substitute. a Litsea mollis; b Litsea mollis oil; c Perilla frutescens; d Acorus gramineus; e Heptapleurum delavayi; f Amorphophallus konjac cakes; g Pteridium revolutum cake; h Nekemias grossedentata; i Nekemias grossedentata tea

Food substitutes and tea substitutes

A total of 9 plant species serve as food substitutes, with Amorphophallus konjac and Pteridium revolutum being particularly favored by the Tujia ethnic group in Laifeng. A konjac tofu, made from tubers, and P revolutum cake, derived from rhizomes, are commonly witnessed in the market town. Nevertheless, the powder production yield for both these plants is relatively low. Informants report that only approximately 3 kg of P revolutum cake can be produced from 50 kg of its rhizomes (Fig. 5f–g).

Six types of tea substitutes exist, among which Nekemia grossedentata, colloquially referred to as “vine tea,” has emerged as a major industry in Laifeng County, exhibiting robust growth (Fig. 5h–i). The Tujia ethnic group of Laifeng harvests the tender stems and leaves of wild N grossedentata in early spring, producing vine tea through the process of kneading, frying, and drying. Studies have indicated that tea brewed from N grossedentata is rich in diverse flavonoids, exhibiting antibacterial and anti-inflammatory properties [46].

Multiple uses of wild edible plants

The 124 species (76.5%) of WEPs traditionally used by the Tujia ethnic group in Laifeng hold not only edible value, but also serve multiple uses such as medicinal, ornamental, material, and fodder (Fig. 6). Of these, 70 species are primarily used for their medicinal purposes. For example, Polygonum sibiricum (Fig. 7a), Eleutherococcus nodiflorus, Aralia echinocaulis, and others are frequently mentioned as medicinal and edible plants for treating conditions like rheumatism, traumatic injury, and bone grafting. Moreover, 23 species are regarded as tonics by the Tujia people in Laifeng, including Corallodicus cordatulus, Sceptridium ternatum, and Disporum longistylum, often used in meat stews for their medicinal properties (Fig. 7b–d).

Fig. 6

Multiple uses of wild edible plants used by the Tujia ethnic group in Laifeng

Fig. 7

WEPs used for multiple uses. a Polygonatum sibiricum; b Corallodiscus cordatulus; c Sceptridium ternatum; d Disporum longistylum; e Caragana sinica; f Taxus wallichiana var. mairei; g Rhododendron simsii; h Phyllostachys edulis pipe; i Zongzi wrapped in Indocalamus tessellatus

In addition, certain WEPs have also been introduced and planted as ornamental plants in the homegardens of the Tujia ethnic group in Laifeng due to their ornamental value, such as Caragana sinica, Taxus wallichiana var. mairei, Rhododendron simsii, and Elaeagnus sp. (Fig. 7e–g). Castanea henryi, Castanopsis eyrei, and Castanopsis tibetana, which belong to the Fagaceae family, are commonly used as firewood and building materials. Musa basjoo, Cryptotaenia japonica, and Oenante Javanica are used as fodder for pigs and poultry. Bamboo is crafted into baskets, dustpans, pipes, among other production tools and everyday utensils (Fig. 7h). The leaves of Musa basjoo and Indocalamus tessellatus are used to wrap cake and Zongzi (Fig. 7i). In addition to making cake, Artemisia indica is also hung outside the door with Artemisia argyi during the Dragon Boat Festival to ward off evil spirits, possessing cultural value. The roots of Rubus setchuenensis are employed in fabric dyeing.

Quantitative evaluation of wild edible plants

The RFC and CFSI were employed to evaluate the value and importance of WEPs among the Tujia ethnic group in Laifeng. The results are shown in Table 2. The CFSI value ranges from 0.05 to 6120. Referring to Pieroni’s research, the CFSI values were divided into 6 groups, namely very high significance (CFSI ≥ 300), high significance (100 < CFSI ≤ 299), medium significance (20 < CFSI ≤ 100), low significance (5 < CFSI ≤ 20), variable low significance (1 < CFSI ≤ 5), and negligible significance (CFSI ≤ 1) [39].

In the 6 groups, the majority of species are clustered in the 4 groups with variable low significance, low significance, medium significance, and negative significance, comprised of 42, 40, 30, and 22 species, respectively. Next are two groups, high significance and very high significance, with 15 and 14 species, respectively.

A heat map analysis was performed on 59 species with high CFSI values in three groups: very high significance, high significance, and medium significance. The results are shown in Fig. 8. When comparing the top 59 species in the CFSI and RFC rankings, a total of 43 species are shared. RFC alone represents the frequency at which a certain species is mentioned by the Tujia ethnic group in Laifeng, while the CFSI is a comprehensive score that includes not only the frequency mentioned, but also indices such as consumption method, consumption frequency, and consumption taste. For instance, Sceptrum ternatum, considered a tonic by the Tujia ethnic group in Laifeng, boasts a good taste, but is relatively rare, with a CFSI of 37.8, placing it within the medium significance. During periods of scarcity, Lactuca indica, Alternanthera philoxeroides, and Chenopodium album were frequently consumed as wild vegetables, yet with the enhancement of living standards, they are presently seldom consumed. Instead, they are utilized as fodder for pigs and poultry, and their CFSI is of negligible significance.

Fig. 8

Heat map analysis of the top 59 CFSI of wild edible plants used by the Tujia ethnic group in Laifeng

Comparison of wild edible plants between Tujia ethnic group in Laifeng and other ethnic groups in different areas

In order to explore the differences in WEPs utilized by the Tujia ethnic group in Laifeng and other ethnic groups in different areas, we conducted a Jaccard index between our study on the Tujia ethnic group in Laifeng and data from five distinct ethnic groups and areas in China [17, 20, 47,48,49]. The results indicate that among the five selected areas, the Gelao ethnic group in northern Guizhou exhibits the highest similarity to our study area, with a JI of 0.20, followed by the Gaowangjie area in Hunan and the Jianghua Yao Autonomous County in Hunan, with JI of 0.19 and 0.17, respectively. The Yi ethnic group in Liangshan Prefecture, Sichuan, and the Zhuang ethnic group in Fangchenggang, Guangxi, demonstrate the lowest degrees of similarity with our study area, with only 0.10 and 0.09, respectively (Table 3).

Table 3 Jaccard similarity index for wild edible plants between Tujia ethnic group in Laifeng and other ethnic groups in different areas