Cyanotype is a photographic printing process that results in a print that is blue. Cyan comes from Greek, meaning a dark blue substance.
The pictures in Blue Prints: The Natural World in Cyanotype Photographs are all, as the title says, cyanotypes of objects from nature - leaves, flowers, feathers, eggs. They are quite striking. Some of them are obviously manipulated to make patterns not seen in nature. "Chicken Egg" (pages 40-41) and "Starfish" (pages 76-77), for example, both have added lines and shapes.
Some of these cyanotypes just look weird. "Toad" (page 29) is a cyanotype of a toad's skeleton, looking very much like a Rorschach print. Others are quite beautiful (many choices; see, for example, "Japanese Painted Fern" on page 59).
There is a very enthusiastic foreward by Tracy Chevalier, author of Girl with a Pearl Earring and, appropriately, The Virgin Blue.