MeSH headings : Freezing; Ice; Rhododendron; Thermography / methods; Plant Leaves / metabolism; Cellulose / metabolism

TL;DR: Observations, together with the leaf- and petiole-histology, and a simulation of the rolling effect of dehydrated leaves using a cellulose-based, paper-bilayer system, suggest that thermonasty occurs due to anisotropic contraction of cell wall cellulose fibers of adaxial versus abaxial surface as the cells lose water to ice present in vascular tissues. (via Semantic Scholar)