Small genets of Lactarius xanthogalactus, Russula cremoricolor and Amanitafrancheti in late-stage ectomycorrhizal successions

We determined the size of genets of late-stage ectomycorrhizal fungi in fie ld sites in coastal Northern California. Basidiocarps were collected, mappe d and subjected to genetic finger-printing 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 markers also showed that R. cremoricolor is dimorphic, with red- and white-capped morphotypes of th is species forming a continuous population Our results suggest that spore p ropagation plays a much more important role in the life history of the Russ ulaceae in undisturbed forest settings than previously recognized. Fungi ap pearing late in the succession sequence and systems without obvious disturb ance therefore do not necessarily colonize primarily by mycelium.