Walter Foster Book, Assorted

William F. Powell was a Very talented artist. I have several of his books. He starts with discussing shading techniques and the pencil grades he prefers. He discusses composition, and floral arrangements. Then he talks about basic flower shapes. On page 7, he starts with simple 4 or 5 step progressions of pictures to show how he draws and shades 28 kinds of flowers. Once you have mastered this book, you would be able to apply this information to draw any kind of flower that you wanted to.