Xishuangbanna Dai Autonomous Prefecture is the study area of the present paper. It is located in the southernmost part of Yunnan Province, China. The Lancang-Mekong River flows through this prefecture from the north to the south, and the whole territory belongs to its watershed. The total land area of the prefecture is more than 19,000 km2, bordering Laos and Myanmar to the south (Fig. 1). It has tropical monsoon climate with an average annual temperature of 15.1–21.7 °C. The annual precipitation varies from 1000 to 2500 mm [31]. Throughout the year, the region maintains a warm and humid climate, characterized by the absence of harsh cold during winter, the absence of extreme heat in summer, and favorable light conditions. Xishuangbanna is the home to the largest tropical forest in China, with an area of approximately 15,500 km2 (81% forest coverage) [28]. The geographical environment and rainforest climatic conditions have nurtured rich local plant resources, with nearly 5000 species of higher plants, accounting for about 16% of China’s higher plant species, making it one of the areas with the richest biodiversity in China [32].

The study area. The colored map is Xishuangbanna Prefecture, in which markets in towns/townships and villages investigated are marked with black dots and blue/pink triangles

Xishuangbanna Prefecture, under the jurisdiction of Jinghong City, Mengla County and Menghai County, has been a multi-ethnic settlement since ancient times. In addition to the Dai people, there are 12 other linguistic groups, including the Han, Hani, Lahu, Bulang, Yi, Jinuo, Yao, Wa and Hui. The ethnic minority population is about 790,000, or 69.97% of the total population, of which the Dai are the most numerous, accounting for about one-third of the total population [33]. In the ancient Dai language, “Xishuangbanna” means “ideal and magical land of happiness” [28]. Each ethnic group has its own language and traditional culture as well as its way of perceiving and using local natural resources, creating a rich cultural diversity in Xishuangbanna [24].

The Dai people live in the basins and lowlands of Xishuangbanna, with a population of 334,500. They have their own oral and writing language belonging to the Zhuang-Dai branch, the Zhuang-Dong language group, Sino-Tibetan family. The Dai people believe the Hinayana Buddhism and animism. They grow sticky rice in the paddy fields and manage homegardens. The glutinous rice is their staple food. Vegetables are mostly grown in homegardens, while wild food plants are collected as supplements (www.xsbn.gov.cn, accessed 21 August 2023).

The Hani people live in the mountains of Xishuangbanna. They have other names such as Aini and Akha, with a population of 211,800. The Hani do not have written language. Their spoken language belongs to the Yi branch, Tibetan-Myanmar language group, Sino-Tibetan family. They grow rice, upland crops such as maize and tea. It is common for the Hani people to collect wild food plants. They believe animism and worship ancestors (www.xsbn.gov.cn, accessed 21 August 2023).

There are 62,100 Lahu people living in Xishuangbanna. They speak Lahu language, which belongs to the Yi branch, Tibetan-Myanmar language group, Sino-Tibetan language family. Most Lahu people believe animism, but some of them believe Buddhism. They live in the mountains and practice upland farming. Collecting edible plants become one of their essential activities.

The Yi people live in the Northeastern part of Xishuangbanna, with a population of 59,500 (www.xsbn.gov.cn, accessed 21 August 2023). They have oral and written language, belonging to the Yi branch, Tibetan-Myanmar language group, Sino-Tibetan family. The Yi people believe animism and worship ancestors. They grow upland crops and collect edible plants in the mountains.

There are 52,800 Bulang people living in Xishuangbanna (www.xsbn.gov.cn, accessed 21 August 2023). They speak their own language but do not have written characters. Their language belongs to the Bulang branch, Mon Khmer group, South Asian language family. They live in the uplands of Menghai County, believe the Hinayana Buddhism. It is essential for the Bulang people to manage teagardens and collect wild edible plants to support their lives.

Most Jinuo people concentrate to live in Jinuo Township of Jinghong City, with a population of 25,800 (www.xsbn.gov.cn, accessed 21 August 2023). They grow upland crops while collecting becomes important livelihood form. The Jinuo people believe animism, and worship their ancestors.

The Yao people live in the mountainous areas of eastern Xishuangbanna, with a population of 23,700 (www.xsbn.gov.cn, accessed 21 August 2023). They do not have written language. Their spoken language belongs to Yao branch, Miao-Yao group, Sino-Tibetan language family. The Yao people grow upland crops and collect wild edible plants for food.

In addition to the Han Chinese, a few thousands of Miao, Wa, Zhuang, Jingpo and Hui people also live in Xishuangbanna. The Hui ran good business, while the others earn their livelihoods based on agricultural production. Most Han people in the prefecture migrated from Hunan Province in 1960s to clear lands for rubber plantations.

Traditionally, the Hani, Bulang, Wa, Yao, Miao, Yi, Lahu and Jinuo people who lived in the mountainous areas practiced shifting cultivation (slash-and-burn agriculture). They cultivated upland rice, taro (Colocasia esculenta), buckwheat and beans, but rarely grew vegetables. The ancestors of uplanders and Han Chinese in Xishuangbanna had planted tea seedlings in natural forests. The old tea gardens scattered in the prefecture can still produce high-quality tea products called Pu-er tea.

Nowadays, all people in Xishuangbanna have gotten rid of poverty and lived at a higher-level livelihoods. The locals who live in lowlands earn incomes from rubber and tropical fruit productions, while those in uplands from tea production. Also, the tourism in Xishuangbanna brings a lot of opportunities to the local people. In general, their economic status is at the middle level in the country. However, the locals still collect a lot of wild edible plants from the forests, farming lands, roadsides and wetlands for daily lives. It becomes a custom or traditional culture to gather food plants from the wild lands.

The field ethnobotanical surveys were conducted in Xishuangbanna during five visits in 2021 and May 2023. It covered 48 villages and 19 markets (Fig. 1) in all three county-level areas, Menghai and Mengla, and Jinghong in the prefecture. Different linguistic groups including Dai, Hani, Bulang, Jinuo, Yao, Miao, Lahu, Yi, Wa, Lisu and Han Chinese were involved.

The maps were downloaded from the official site (http://bzdt.ch.mnr.gov.cn/). The investigation sites including markets and villages were marked based on ArcGIS 10.7.

In villages, free listing, key informant interviews and participatory observation were conducted [34, 35]. In total, 201 people ranging from 16 to 87 years old were interviewed during the field surveys, including 92 females. The informants were mostly interviewed in local markets, reaching 128 people consisting of 65 females and 63 males (Table 1). Among these respondents, 24 people were selected as the key informants. In the context of this article, EFs are defined as floral components consumed by individuals for culinary, beverage, or supplementary dietary purposes. Consumption may involve the flower alone or in combination with other plant parts. The interviews were conducted using a semi-structured approach, covering topics such as EF species, their pronunciation, edible parts, processing techniques, medicinal advantages of consuming the flowers, additional uses of the consumed plant, and the motivations behind their consumption.

The linguistic group, age, education level and occupation of informants were also recorded. Before the interviews, each informant who participated in was informed of the purpose of the project, and their consent was obtained.

The availability of the EFs influenced by seasons and processing, making comprehensive coverage challenging in limited field surveys [19]. A pivotal reference for this study was the comprehensive investigation by Prof. Yitao Liu and Prof. Chunlin Long (one of the corresponding authors of this paper), pioneers in the field of edible flowers in Yunnan [21, 22]. Local market was the entrance of local food system with the largest concentration of flower-eating plants in the region [3]. They were also gathering places for traditional knowledge from the stallholders and consumers [17]. In our survey, we examined 19 markets within an urban area and 11 towns across Xishuangbanna. Our interviews encompassed EFs' vendors as well as select consumers purchasing these items. The traded flower-eating plants in the markets and supplementary insights shared by local individuals (both vendors and consumers) were meticulously documented.

The flowers collected and consumed by the local people in Xishuangbanna can be divided into different categories according to their edibility of different parts of the flower. A single flower consists of bract, pedicel, receptacle, calyx, petal and corolla, stamens (filament, anther and pollen), pistils (ovary, style and stigma), nectars, and sometimes appendix. In many cases, there are inflorescence consisting of flowers. People consume flowers together with leaves and stems if all these parts are edible or taste better. But sometimes only a single part of flower (for example, petal or pedicel), or male flower only, is selected for food. Therefore, the edible parts of EFs were recorded and calculated in the market surveys and field investigations.

The multiple uses of flowers including their cultural values were also investigated. Some species of EFs consumed as food can be used for different purposes such as ornamentals, medicine and pigment. The EFs have contributed to the development of local culture in Xishuangbanna. Their values with cultural significance were also investigated and recorded, in addition to their role as food.

The voucher specimens were collected through the process of conducting market surveys or en route to subsequent locations. The nomenclature of all vascular plants follows Plants of the World Online (Kew) (powo.science.kew.org, accessed on 16–17 August 2023) and World Flora Online (www.worldfloraonline.org, accessed on 23–28 May 2023). Prof. Chunlin Long and Zhuo Cheng identified the plant species, and the voucher specimens were deposited in the herbarium at Minzu University of China, Beijing.

Quantitative analysis of the data was conducted to understand the diversity of edible flower species in Xishuangbanna. It will help to evaluate the potential of traditional knowledge of the target communities. Thus, the number of species, the number of respondents who provide information, and information on the edible flower species were presented based on the citations. Our quantitative analysis was followed by ethnobotanical indexes using relative frequency of citation.

The relative frequency of citation (RFC) in this study was used to evaluate the local importance of EFs in Xishuangbanna. The formula for RFC is RFC = FC/N, which means the number of respondents mentioning an EF divided by the total number of respondents [36]. FC is the number of respondents who gave citations at each species, and N is the number of respondents. The index varies from 0 to 1. A higher RFC value means more local people know the EF [37]. The RFC values for each EF are added to the database.