Solution: Short day plants require long period of darkness and short period of light to flower. Long day plants will flower when they are exposed to short period of darkness and long period of light. Long day plants flower in summer and short day plants flower in spring. Day neutral plants do not depend upon the amount of darkness or daylight hours. Examples of day neutral plants are sunflower, cucumber, tomato. Examples of short day plants are rice, tobacco, cotton. Examples of long day plants are lettuce, spinach, potato. Bryophyllum is a long short day plant. It requires a certain number of short days preceded by a certain number of long days to flower.