Birch Witch's-Broom 
Birch Woodwart 
Bisporella citrina 
Black bulgar 
Black Knot 
Black Morel 
Black Sooty Mold 
Black Tar Spot 
Black-Eye Lichen 
Bleach cup 
Blistered Cup 
Blue Jellyskin 
Bolete eater 
Boreal button lichen 
Boreal Oakmoss 
Botryosphaeria dothidea 
Bottlebrush Frost Lichen 
Branched pixie-cup lichen 
Bristly Tropical Cup 
British soldier lichen 
Brittle cinder 
Brown-eyed Camouflage Lichen 
Browned Pixie-cup Lichen 
Buellia stillingiana