Thinleaf Sunflower

Have you ever heard of thinleaf sunflowers?  I had never heard of them, until today.  However, I've SEEN them dozens of times.  

Here's a picture:

See the thinner, sharply pointed leaves?

These sunflowers are also called "ten-petal sunflowers", although they can actually have 8 - 12 petals.  They are woodland flowers, and I found these in western Illinois.

Butterflies seek out this plant to lay their eggs, and muskrats favor this plant as well.  

The species name is Helianthus decapetalus.  Isn't that perfect?  Helianthus comes from Helios, god of the sun (that equates with Hyperion of Green mythology), and decapetalus represents the ten petals.