Long-day plants are classified due upon the time period of flowering, as will be found with the categorization of short-day plants. The distinctive, underlying characteristic of long-day plants, that in the northern hemisphere they will blossom, typically in late spring, early summer, when daytime is at its longest, hence “long-day plants”, this period will often last till June 21st, the Summer Solstice, the longest day of the year, as the days will often shorten following this date, in the northern hemisphere. However, in the southern hemisphere it is quite the contrary, as everything is in reverse, as December 21st is the longest day of the year there. Furthermore, there are numerous examples of long-day plants, such as oats, clover, bellflower, peas, barley (Like the Heineken seen above, containing barley), lettuce, turnip, wheat, and so on. As can be seen, it is quite intriguing to understand how critical a photoperiod may be to the development of a plant.