The plants are about six feet tall right now, and just this past week the flowers opened up. Considering that it is now August, they are a bit behind in terms of the growing season here.
Still, "hundreds of seeds" seemed like a stretch. The first thing I noticed about the giant plants was the spiral pattern inside the flowers themselves and how tightly wound it was. I then went and did some research on Wikipedia, and discovered that :
"The florets within the sunflower's cluster are arranged in a spiral pattern. Generally, each floret is oriented toward the next by approximately the golden angle, 137.5°, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower there could be 89 in one direction and 144 in the other. This pattern produces the most efficient packing of seeds within the flower head."That's what I like to read: "This pattern produces the most efficient packing of seeds within the flower head." Translation: more seeds!
Then, there is this random tibdit: sunflowers can be used to extract toxic metals from the soil. I have no idea how that works. Maybe I don't want to know, either.
Still, the fact that a six to ten foot plant emerges with tons of seeds that are efficiently packed is pretty amazing.