This document defines and describes various plant responses and adaptations, including tropisms like thigmotropism and phototropism, short-day and long-day plants and their response to photoperiodism mediated by the phytochrome pigment, dormancy which allows plant embryos to survive without growing, and the abscission layer which seals off leaves from the vascular system. Key concepts are that tropisms demonstrate how plants respond to external stimuli, photoperiodism times seasonal activities, and deciduous plants prepare for winter by transporting materials and sealing off leaves.