Reproductive and Pollination Characteristics of Three Understory Impatiens Species

Understory flowering plants often face limitations in pollinator availability. This necessitates an investigation of pollination mechanisms and reproductive traits to understand their survival strategies. Floral syndromes, which are critical determinants of plant–pollinator coevolution, significantly impact the reproductive success and diversification dynamics of angiosperms. The genus Impatiens is known for its remarkable floral diversity and varied pollination systems and it is also serves as an exemplary model for examining plant–pollinator interactions. Therefore, this study was performed to elucidate the pollination characteristics and breeding systems of three sympatric species, Impatiens davidii, Impatiens jinggangensis, and Impatiens commelinoides. The results indicated all the Impatiens species exhibited similar individual flower longevity (4–5 days). However, I. commelinoides and I. jinggangensis peaked in July-August, whereas I. davidii primarily flowered in August-September. These species shared a self-compatible breeding system that requires pollinators for facultative outcrossing, with bumblebees (Bombus) and polyester bees (Amegilla) identified as the primary pollinators. The presence of wing petals had a significant impact on fruit set in both I. davidii and I. commelinoides. The three Impatiens species demonstrated notable interspecific differences in their floral scent profiles, accompanied by distinct variations in floral morphology and scent characteristics. These differences collectively represent pollination strategies and life-history tactics that highlight pronounced interspecific divergence. The variation in pollination strategies is attributed to the synergistic interaction between floral morphology and scent chemistry. Thus, these findings offer valuable insights for the investigation of forest understory plant conservation, resource utilization, and co-evolutionary relationships with primary pollinators.