Scanning electron micrograph (SEM) of a wing feather from a lanner falcon (Falco biarmicus). The feather has numerous parallel barbs, which branch from a central stem called a rachis (not seen). The barbs themselves branch into thin parallel barbules, which terminate in tiny hooks (barbicels), which attach to the adjacent barbule. These links allow the feather to present a flat blade. The lanner is a large falcon that inhabits open country in Africa, southest Europe and western Asia.