Hygroscopic stem reshaping promotes long-distance plant dispersal.

Cleistogenes squarrosa is a pioneer tumble plant widely distributed across the Eurasian steppes. It achieves long-distance wind dispersal through stem reshaping. However, the underlying ecological adaptation mechanisms of this dispersal strategy remain unexplored. Combining with field and laboratory observations, we revealed that four coordinated processes - plant phenology, cell wall development, water supplies, and aerodynamic adaptations - interactively facilitate the anemochory of this endemic species in the Eurasian steppes. Specifically, the development of the cell wall with heterogeneous microfibril arrangement plays a critical role in hygroscopic stem reshaping, which occurs in synchrony with seed maturation. Remarkably, the subsequently dry and windy season perfectly follows these two synchronized processes, providing ideal dehydration conditions for stem reshaping and enhancing aerodynamic efficiency for long-distance dispersal. This model for long-distance dispersal innovatively showcases how microscopic cell wall structure propels macroscopic dispersal capabilities and environmental adaptation, ultimately enhancing ecosystem resilience to environmental changes. Collectively, these results indicate the potential for promoting the introduction and cultivation of C. squarrosa to support the restoration of degraded and arid ecosystems. Moreover, this newly identified mechanism provides a valuable direction for future research aimed at developing herbaceous plant varieties with improved dispersal capabilities through molecular breeding techniques.