Plant dyes are natural colorants and cultural heritage that reflect human perceptions of nature and have made significant contributions to human civilization [1]. Plant dyeing refers to the extraction of natural pigments from various plant parts, such as flowers, fruits, roots, stems, and leaves, and the use of methods such as immersion dyeing or mordanting to color fabrics [2]. Plant dyeing, a natural dyeing technique, has garnered significant attention in the context of the sustainable economy. The environmental friendliness of natural dyes has expanded the application of plant dyes in the food, fabric, and pharmaceutical industries [3]. Natural dyes are widely favored as high-quality alternatives to synthetic dyes [4]. Although chemical dyes dominate the modern textile industry, plant dyes are still widely used in ethnic clothing, such as Dong people using Strobilanthes cusia and Dioscorea cirrhosa for cloth dyeing [5], Zhuang people making black garments and five-color rice [6], and traditional clothing of the Baiku Yao [7](Fig. 1). The application of dyeing plants not only preserves ethnic identity but also embodies the wisdom of harmonious coexistence between humans and nature.

China has a long-standing history of plant-based dyeing, with a rich tradition of dyeing plants, particularly in remote mountain villages [7]. However, issues such as limited color variety, fading, and complex extraction processes hinder the widespread application of plant-based dyes [8]. Chemical dyes have gradually replaced natural dyes because of their low cost, wide color range, ease of acquisition, and resistance to washing and sunlight [9]. However, chemical dyes pose risks to human health and the environment owing to their non-biodegradable, non-renewable, toxic, and carcinogenic properties [10]. This has prompted scientists and researchers to seek sustainable alternatives to mitigate environmental pollution. Dyeing plants offer environmental benefits, are renewable, produce natural colors, have a soothing effect on the eyes, and are non-toxic and harmless [11]. Additionally, many dye plants also have edible and medicinal values [12, 13, 14]. For example, curcumin from Curcuma longa has antitumor, anti-inflammatory, and antioxidant effects [15].

Guangxi is a multi-ethnic autonomous region located in southwestern China, with the Zhuang ethnic group as the main population. Its unique geographical location and favorable climate have fostered rich biological and ethnic cultural diversity [16, 17]. As of December 2023, 10,466 species of native higher plants have been identified in Guangxi [18]. The history of plant-based dyeing in Guangxi is long-standing, particularly among ethnic minorities. For example, the Zhuang use Liquidambar formosana, Curcuma longa, and Peristrophe bivalvis to create five-colored glutinous rice [19]. The Dong use Strobilanthes cusia and Toxicodendron succedaneum for indigo dyeing of Dong cloth [5], the Napo Zhuang use Strobilanthes cusia and Toxicodendron succedaneum to create black Zhuang clothing [6], and the Nandan Baiku Yao mix Strobilanthes cusia, and Vernicia fordii to create a dye solution for their clothing [7]. With the growing awareness of environmental protection, plant dyes are increasingly being used in modern textiles, and related research has become a popular topic [20]. Therefore, it is urgent to research dyeing plants in Guangxi, which will not only provide a scientific basis for biodiversity conservation but also promote the sustainable use of natural dyes.

To systematically document Guangxi’s dye plants and techniques, we conducted a comprehensive ethnobotanical survey and systematically assessed the parts of dye plants used in Guangxi, their applications, dyeing techniques and effects, harvesting seasons, and challenges. The objectives of this study are as follows: (1) to compile statistics on the types of dye plants used in Guangxi and their distribution characteristics and to compile a detailed plant catalog; (2) to explore the methods of using dyeing plants in the local area and the cultural connotations behind them; and (3) to assess the dyeing plants preferred by local people. By systematically organizing this traditional knowledge, we can not only promote the protection and development of dyeing plants in Guangxi but also provide a scientific basis for biodiversity conservation, facilitate the development of new environmentally friendly dyeing and weaving products, and promote the inheritance of minority cultures.

This survey was conducted 12 times between March 2021 and October 2024, covering different seasons and dye plant harvest periods to ensure that the information collected was representative and timely. Based on records from references, suggestions from the local government, our knowledge and experience, and the results from snowball interviews, 26 villages and 10 traditional markets in Guangxi were selected as study locations (Table 1,Fig. 2). Before each interview, informed consent was obtained throughout the study [23]. A total of 262 informants were interviewed in the study area (100 males and 162 females); among them, 82 were key informants, and the remaining 180 were selected using a snowball sampling method from the market and village. The ages of the survey participants ranged from 10 to 82 years. We gathered traditional information from local residents about commonly used dye plants, documenting their habitats, parts used, purposes, dyeing processes and effects, and harvesting seasons. Of the informants, 80% were over 45 years old, most had a low education level, and the informants were almost equally male and female. Product samples and voucher specimens were collected from markets, mountains, forests, and farmland. In addition, photographs of all plant species and gathering activities were taken simultaneously. Voucher specimens of all plants available during field investigations were collected and deposited in the herbarium of Guangxi Institute of Traditional (GXMI), Guangxi Institute of Traditional Medicine and Pharmaceutical Science. Product samples, voucher specimens, and photographs were identified and confirmed by referring to Flora of China, Flora of Guangxi, and botanical websites (e.g., http://www.tropicos.org/, http://www.cvh.ac.cn/search, http://www.plant.csdb.cn/). The botanical names were listed following the Plants of the World Online database (https://powo.science.kew.org). Finally, the identified specimens were confirmed by other taxonomists at GXMI, and a list of dyed plant species was compiled.

This study used relative citation frequency (RFC) to evaluate the traditional utilization value of dye plants in Guangxi (Table 1). RFC reflects the relative importance of dye plants in Guangxi. The RFC values of all dye plants ranged from 0 to 0.66, with the highest value being that of Liquidambar formosana (RFC = 0.66). As the most frequently used dye plant, its leaves can be crushed to extract black dye, primarily used for food coloring (e.g., the source of black pigment in Guangxi's five-color glutinous rice). The availability of leaves throughout the year enhances the convenience and practicality of maple dyeing. Buddleja officinalis is the second (RFC = 0.63), with the flowers as the dyeing part. Yellow dye is obtained through decocting and is widely used in food and silk threads, such as the five-color glutinous rice dish in Guangxi and the cured meat and yellow flower rice dish in Daxin County, Chongzuo City. Impatiens balsamina (RFC = 0.58) uses flowers as the core dyeing part. After being pulverized, it is directly used for fingernail dyeing (commonly known as “fingernail dyeing flower”), and its vibrant red color makes it an important dyeing plant in summer. Strobilanthes cusia (RFC = 0.57) contains blue pigments, and most plant-dyed blue fabrics use Strobilanthes cusia. Curcuma longa (RFC = 0.56) has stems that, when crushed, can dye food and silk threads yellow. The high RFC values (> 0.56) of these five plants reflect their central role in Guangxi’s dyeing traditions and their significant potential for development and utilization. (Fig. 5)

Guangxi boasts a rich variety of dye plants, providing the color foundation for local traditional fabric and food, and holds significant value for utilization and conservation. Traditional dyeing techniques in Guangxi primarily rely on simple processes such as pulverizing and decocting, not only preserving ancient dyeing skills but also fostering a dyeing culture that combines practical, medicinal, and symbolic significance. These findings are important for the development of environmentally friendly and healthy dyes, regional economic development, the inheritance of ethnic culture, and the protection of biodiversity. However, Guangxi's dyeing plants face challenges from chemical dyes and difficulties in industrialization. Future efforts should focus on three areas: resource protection, process innovation, and industrial integration. This will promote sustainable utilization and industrial development, protect traditional knowledge, and provide scientific theoretical support for a green economy.