Collections in global botanical gardens reveal charismatic species bias in conservation

Biodiversity conservation efforts are often concentrated on a narrow subset of charismatic species, which attract disproportionate attention and funding.¹ While this bias is usually reported in animal conservation,^2,3,4 whether botanical gardens exhibit similar patterns remains poorly understood. Recent studies have revealed geographic and taxonomic imbalances in botanical garden collections,^5,6,7 but which species drive these patterns and the underlying mechanisms remain unexplored. China is recognized as the "mother of gardens" for its contribution to global horticultural diversity.^8,9 The long introduction history of Chinese endemic plants provides an opportunity to examine the historical factors shaping current ex situ conservation patterns. We analyzed 5,158 Chinese endemic plants across 636 botanical gardens, revealing that 43 species (0.83%) appeared in 100 or more gardens. Ginkgo biloba and Metasequoia glyptostroboides appeared in more than 300 gardens, whereas 45% existed in only a single garden. The factors that promoted the widespread collection of certain Chinese endemic plants in botanical gardens include not only ornamental or conservation value but also relict "living fossil," centuries-long introduction histories, and cultural symbolism. Species co-occurrence network analysis revealed that Rhododendron co-occurrence across gardens is far from random. These Rhododendron hub combinations are held almost exclusively by gardens outside China (94.7% of holding gardens), reflecting Rhododendron-focused collecting by Western plant hunters during the late 19th and early 20th centuries in China. Our findings demonstrate that botanical garden collections must shift from charismatic species bias toward conservation-driven strategies that prioritize underrepresented endemics based on extinction risk rather than horticultural fame.