We determined the size of genets of late‐stage ectomycorrhizal fungi in field sites in coastal Northern California. Basidiocarps were collected, mapped and subjected to genetic fingerprinting using amplified fragment length polymorphisms (AFLPs). The minimum size estimates for the largest genets of Amanita francheti , Lactarius xanthogalactus and Russula cremoricolor were 1.5, 9.3 and 1.1 m 2 , respectively. The molecular mark...