Hypomyces cervinigenus 
Hypomyces luteovirens 
Hypomyces melanocarpus 
Hypomyces papulasporae 
Hypotrachyna livida 
Hypoxylon multiforme 
Hypoxylon Oak Canker 
Hypoxylon tinctor 
Imleria pallida 
Inocutis dryophila 
Inocybe fuscodisca 
Inocybe lacera 
Inocybe mixtilis 
Inocybe subochracea 
Inocybe tahquamenonensis 
Inocybe xanthomelas 
Inonotus obliquus 
Inonotus quercustris 
Inosperma subrubescens 
Insidious Gomphidius 
Iodine bolete 
Irpex lacteus 
Irregular Earth Tongue 
Ivory bonnet