Why do flowers smell more at night? While not all flowers do this, there are many flowers with a biological clock that results in the emission of more smell at night. The pleasant smells from plants are chemicals that are easily evaporated and disappear in the hot sun. As a result, flowers have evolved genes that lead to more smells being released at night along with an opening of the flower making it easier for insects to enter the flower and help with pollination, which is how flowers reproduce. Their male part has tiny grains of DNA called pollen which is the sperm of the plant. These grains are carried from flower to flower on the legs of pollinating insects such as bees. The bees are attracted by color and smell, but are really seeking the sweet nectar in the center of the flower. As they remove the nectar, they leave the pollen clinging to the female part of the flower called the stamen.
Plants have complex biology and evolved in a different direction than humans. However, they can be very complex with some plants catching and digesting insects such as the venus fly trap. The flowers with the most variety are orchids with over 4000 different colors and shapes all directed at attracting insects to help them reproduce.