One of the things nobody in this list seems to be taking into account is that we are unable to imagine just what a bird sees when it looks at a flower. Birds have 4 types of color receptors, while we have only three. And the colors they are sensitive to are more widely separated than ours. They can see colors totally invisible to us. So, we might look at a yellow flower and conclude it is plain and simply yellow, while the hummingbird sees it as having a compelling color design, which might not even be different, except for shade, from that of a red flower. Whatever draws the hummers to particular flowers, I'm certainly glad we can list those which attract them, so that we can grow them. Now, who's going to start a thread on butterfly attracting flowers? David