Here are some Collarette, Single, Orchid and Orchette open forms, all from shows or other gardens...

Gorgeous! I didn't have many of these types on my wish list this year but maybe next year.

I especially love the one with the bee giving the dahlia a bear hug :)

I grow all my open-centered dahlias around my apiary (honey bee area), and along my raspberry rows wherever I can squeeze the extras in. They have such a light and fun feel, contrasting almost too much with the majestic and elegant feel of most other forms of dahlias.

Dahlia hybridizers that are trying to breed for ball, waterlily or cactus forms traditionally stay well away from growing any open-centered or laciniated (frilly-petalled) forms, as those traits are dominant, and the resulting seedlings are disappointingly opposite of their goals.