Poisonous delicacy: Market-oriented surveys of the consumption of Rhododendron flowers in Yunnan, China

Ethnopharmacological relevance: Plants from the family Ericaceae, and in particular those in the genus Rhododendron are frequently reported to contain grayanotoxins. Plant products such as honey and herbal medicines made from these plants occasionally contain grayanotoxins, and in turn may lead to intoxication. The balance between the benefits and risk of poisoning from Rhododendrons is of concerns. This study explores the ethnobotanical knowledge of the people in Yunnan, China as regards the consumption of Rhododendron flowers, and gives special focus to their assessment of the benefit-risk balance.

Materials and methods: An ethnobotanical survey was conducted across 14 county-level local markets in north and central Yunnan province, during which a total of 82 stalls selling Rhododendron flowers were visited and 204 people were interviewed. Voucher specimens were obtained under the guidance of collectors, and details about local practices and knowledge were recorded using semi-structured interviews and participatory observations.

Results: The consumption of the corollas of Rhododendron decorum Franch. flowers (RDf) or Rhododendron pachypodum Balf. f. & W.W. Sm. flowers (RPf) as a seasonal delicacy is a long-standing tradition in the study area. RDf are widely consumed in northwest and northeast Yunnan, while RPf are more prevalent in the central regions of Yunnan, and there is a high consistency in the knowledge of the process for detoxification or palatability for each species. The main reasons for eating the flowers were listed as health benefits (mostly clear heat), wild collected, tradition and good flavor. All RPf consumers stated that the corolla from this species is not toxic, while 67.4% of the RDf consumers claim that the corolla from RDf is toxic. We compared the two species and analyzed their process intensities, poisoning cases and cautions, market trade forms and existing toxicity studies, which agreed well and consistently that the corolla of RDf deserve more toxicity attention than RPf.

Conclusion: Our study provides a window to look into the ways, beyond honey and herbal medicine, by which Rhododendron species have influenced human wellbeing. The local culture can justify eating Rhododendron flowers, and meanwhile, has developed a series of skills to avoid the side effects of eating them, and therefore the study also provides a good case to answer more general questions about the rationality of eating any plant products by assessing the trade-off between benefits and side effects.

Keywords: Edible flower; Ethnobotany; Florivory; Grayanotoxin; Wild food plants.