Here’s some interesting facts about sunflowers from WikiPedia
What is usually called the flower is actually a head (formally composite flower) of numerous flowers (florets) crowded together. The outer flowers are the ray florets and can be yellow, maroon, orange, or other colors, and are sterile. The florets inside the circular head are called disc florets. The disc florets mature into what are traditionally called “sunflower seeds”, but are actually the fruit (an achene) of the plant. The true seeds are encased in an inedible husk.
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