Nikon Small World - Winning Photos

Each year Nikon sponsors a photo contest of small subjects, many of which, but not all, are biological. Usually a number of the subjects are botanical too, although perhaps fewer this year than in the past, and of those, too many, including the winning image, are of one plant species, Arabidopsis thaliana, the botanical equivalent of a lab rat, whose common name is, appropriately enough, the mouse-ear cress. Here's another botanical image taken by Dr. Shirley Owens of Michigan State University. Can you guess what these are? Here's your hint, but it won't help: they are magnified 450X and are found on the black-eyed susan vine.