This study interviewed 161 informants from three communities in the Rongjia Township (Table 1). Among the informants, 106 were men and 55 were women. The number of male informants (65.84%) was almost twice as high as that of female informants (34.16%). When we used the snowball sampling method to select informants, they mostly recommended men. In addition, in the process of our household interviews, men in the family usually came forward to be interviewed, whereas women often did not. The ages of the informants ranged from 18 to 99 years. The mean age of the informants was 51 years. All informants of the township are Tibetan.

Fifty wild edible plant species belonging to 28 families and 42 genera were identified (Table 2). The results showed that the most frequently mentioned family was Rosaceae (seven species), followed by Amaryllidaceae (four species), Brassicaceae, Ericaceae, Grossulariaceae, and Polygonaceae, each containing three species. Five families comprised two species. The remaining 17 families contained only one species each (Table 2). At the genus level, the most common genus was Allium (four species), followed by Ribes (three species), Lindera (two species), Rosa (two species), and Zanthoxylum (two species). The life forms of these WEPs were mostly herbs (29 species) and shrubs (13 species) (Fig. 2).

We found that many parts of the plants were consumed, such as the leaves, fruits, stems, seeds, and roots (Fig. 3). The most commonly consumed part was the leaves (19 species), followed by fruits (17 species) and stems (six species). Wild vegetables and fruits were the two main categories of WEPs. The parts used for wild vegetables were the leaves, whereas the parts used for wild fruits were the fruits.

Based on the information provided by the participants, we summarized the WEPs into six categories (Table 3). The WEPs consumed by the Tibetan people in the Rongjia River Valley included vegetables, fruits, spices, healthcare food, substitute grains, and beverages. Wild vegetables were the most commonly consumed (24 species), followed by wild fruits (12 species).

The WEPs were typically collected from April to September (Fig. 4). The collection time for WEPs depended on the maturation of the parts used. Most of the wild vegetables were collected from June to July. Wild fruit was collected primarily from July to September.

Months of collection for WEPs

Half of all species were wild vegetables (24 species) belonging to 17 families: Brassicaceae and Polygonaceae (each having three species); Amaranthaceae, Apiaceae, and Ericaceae (each having two species); and the remaining 12 families each having one species. The main edible parts were the tender leaves and stems. Wild vegetables were usually collected from April to September and used only for the family’s own consumption, not for sale. The processing method was found to be relatively simple, usually involving boiling and then stir-frying or making soups. The three most frequently mentioned species were U. hyperborea (RFC = 0.71), Heracleum nyalamense R. H. Shan & T. S. Wang (RFC = 0.56), and Chenopodium album var. viride (L.) Pursh (RFC = 0.52).

U. hyperborea is a seasonal vegetable, and Tibetans in the Rongjia River Valley only collect and consume it from April to May. Because U. hyperborea stems and leaves have sharp thorny hairs, they have unique collection and processing methods. Most locals wear gloves and use scissors to collect the tender leaves of U. hyperborea for consumption. To handle the sharp thorny hair, they were rinsed slightly with boiling water prior to cooking. After boiling, the prickly hair of U. hyperborea did not cause any irritation to the skin; therefore, U. hyperborea was added to the broth and cooked into a thick soup. During the interviews, many informants (n = 64) said that they had to eat U. hyperborea once a year.

H. nyalamense is endemic to Tibet, and Tibetans in the Rongjia River Valley collect it annually from June to August. The stem can be peeled and then eaten raw. Interestingly, when local people go up to the mountains, they consume H. nyalamense as a snack.

C. album var. viride can be consumed in several ways. After collection from April to May, its tender leaves can be cooked, fried, steamed, stuffed into buns, or added into a broth like U. hyperborea to make a thick soup.

Fruits (12 species) were the second largest use category of WEPs, belonging to five families: Rosaceae (six species), Grossulariaceae (three species), and the remaining three families each having one species. Wild fruits were found to be available from June to September, and all fruits were used only for the family’s consumption and not for sale. They were typically consumed as fresh fruits, such as snacks, and their main edible parts were fruits. The three most frequently mentioned species were Rosa sericea var. glandulosa Osmaston (RFC = 0.76), Rosa macrophylla var. glandulifera T. T. Yu & T. C. Ku (RFC = 0.68), and Fragaria nubicola Lindl. ex Lacaita (RFC = 0.68), which was observed throughout the Rongjia River Valley.

R. sericea var. glandulosa and R. macrophylla var. glandulifera are wild fruits of the Rosaceae family that ripen in July. These two wild fruits are very similar in appearance. R. macrophylla var. glandulifera requires peeling and removal of the small thorns before consumption, while R. sericea var. glandulosa can be consumed directly.

F. nubicola matures in September and typically thrives in habitats such as ditches, forest areas, and hillside grasses. The ripe fruit can be eaten directly as wild fruit. Thus, these three plants are important and readily available as wild fruits for vitamin C supplementation between July and September.

Seasoning are an important food category for WEPs in the Rongjia River Valley, with ten documented species belonging to five families: Amaryllidaceae (four species), Lauraceae and Rutaceae (having two species each), and the remaining two families each having one species. Data were collected from April to September. The main edible parts of these plants were found to be the fruits. The three most frequently mentioned species were Zanthoxylum bungeanum Maxim. (RFC = 0.75), Zanthoxylum acanthopodium DC. (RFC = 0.66), and Allium wallichii Kunth (RFC = 0.53).

The ten seasoning plants were used in a similar manner by the local people, grind seasoning plants, adding chili peppers mixed for seasoning (Fig. 5). Potatoes are the main food crop in the Rongjia River Valley, and it is common practice to season them with these homemade spice blends. In addition to potatoes, locals use these homemade spice blends for their various other staples. Although the method of consumption is consistent, distinct plants and proportions produce diverse and delicious flavors cherished by the local people. Notably, A. wallichii, which has an excellent flavor, has been introduced into home gardens by the local people.

A The most commonly used seasoning, Zanthoxylum bungeanum Maxim. B Tools used for grinding wild seasoning plant. C A homemade seasoning used for serving with flatbread

Three substitute grains were also observed, including Arisaema erubescens Schott (RFC = 0.18), Pinellia ternata (Thunb.) Makino (RFC = 0.17), and Satyrium nepalense var. ciliatum (Lindl.) Hook. f. (RFC = 0.17).

From June to September, A. erubescens tubers are collected by the local people and are subsequently peeled and served. One informant reported that "after eating A. erubescens once, we have completed a great event in our life." We also found that before the liberation of the Rongjia Township, some farmers would go to their landlord's house to help them hoe the fields for free in order to collect A. erubescens from the land. At that time, the local people were very dependent on A. erubescens.

The consumption of P. ternata is special. Its seeds are collected from July to August and are washed, ground, wrapped, and buried for seven days. Finally, the mixture is stirred with highland barley flour to prepare dough bread.

Although reports were collected (n = 11), we discovered that A. erubescens and P. ternata are no longer utilized. However, in the former Rongjia River Valley, these were important substitutes for grain plants.

S. nepalense var. ciliatum is consumed in a unique manner. Locals collect their tubers from August to September every year, wash and steam them, remove the skin, and grind them into a cylindrical shape—similar to that of sausage—before consumption.

Five WEPs from other food categories, including healthcare food and beverages, were identified. Four species were found to have medicinal value and have been used to treat rheumatism, sore throat, toothache, rhinitis, cold, and begma. The three most frequently mentioned healthcare foods were Z. bungeanum (RFC = 0.75), Z. acanthopodium (RFC = 0.66), and Rhododendron anthopogon subsp. anthopogon (RFC = 0.32).

Z. bungeanum and Z. acanthopodium are simultaneously used as seasoning and healthcare food by Tibetans in the Rongjia River Valley. After chewing Z. bungeanum, it is applied for toothache, having an analgesic effect, while soaking it in water is said to prevent rheumatism. Some informants (n = 6) mentioned that for people with hypertension, it is necessary to use Z. bungeanum as little as possible, as it can lead to increased blood pressure.

R. anthopogon subsp. anthopogon leaves are collected in June and July of each year and are chewed as a snack by Tibetans in the Rongjia River Valley. Soaking the leaves of R. anthopogon subsp. anthopogon in water is employed to treat colds and begma. These medicinal plants are important for residents to improve their health and prevent diseases.

Only one wild plant was used as a beverage by the Tibetans in the Rongjia River Valley: Berchemia edgeworthii Lawson. Local people collect B. edgeworthii leaves in May and June of each year, which are then dried, stored, and soaked in drinking water.