Thigmotropism is a response to touch. Nastic movements are not oriented toward a stimulus. Thigmonasty is response to contact. Nastic response to light and dark is photonasty, caused by osmotic changes that differentially alter cell volume. Thigmomorphogenesis is a growth-inhibiting response to mechanical disturbance.
Plants sense seasonal and other environmental changes.
Photoperiodism is the ability of a plant to measure length of day and night. Flowering can depend upon photoperiodism. Intermediate-day plants require days of intermediate length to flower. Day-neutral plants do not use light or dark cues to flower. The type of plant determines the season when it flowers.