Why is a sunflower yellow

Sunflowers are annual flowers with a thick and fairly big flower head usually consisting of bright yellow petals. These Native American flowers are known as the sunflower because of the overall shape and structure of the flower. The receptacle and the petals together resemble the sun with bright yellow flames coming out of it and thus the name sunflower. There is a belief that sunflowers follow the sun’s movements throughout the day but that is not entirely correct. Although the sunflower buds and leaves follow the sun from east to west, the fully blossomed flowers do not do the same. The heliotropism is discontinued by the sunflower plant once it has reached maturity. The photosensitive movement of the young sunflower plant and the overall look of its flowers jointly had contributed to the origin of the name “sunflower”.

As is the case with everything else as well, sunflowers look yellow to us because yellow is the only wavelength of light that the flower does not absorb and thus reflects back. However, the real question is “why sunflowers reflect this particular color?” All colored flowers are colored for a reason and almost always, the reason is to attract insects and birds to them. The pigment in the sunflower enables it to reflect the light wavelengths in such a manner that what appears yellow to human eyes, appeals to the butterflies and honeybees enough in order for them to be attracted to the flower. The large flower base of the sunflower also acts as an appropriate base for the insects to settle on. The reason as to why the flowers have evolved in this way to attract insects to them is of course, pollination. As plants cannot move on their own, they need agents to carry the pollen from the anther of a stamen to the stigma of a carpel in order for the species to breed and survive. Wind and water serve this purpose up to a certain extent but they are not effective enough in certain places for certain species and thus the sunflower has evolved to attract insects with their bright yellow color.

After the attracted insect settles on the flower, the nectar within the sunflower acts as a reward for the insect. The sweet nectar is consumed or stored as food by the pollinators and that also ensures the fact that the insect, in its search for more nectar will again sit on the next flower of the similar kind that it finds. Each time the insect sits on an anther, it picks up the pollens and each time it sits on a stigma, the fertilization process becomes a success. The relation between the flowers and their locomotive pollinators are a relationship of mutual benefit.