 Lactarius deterrimus has traditionally been considered to have a strict mycorrhizal host specificity with Norway spruce . In 2006 , it was reported that the fungus can also form arbutoid mycorrhiza with bearberry ( Arctostaphylos uva @-@ ursi ) . Arbutoid mycorrhizal associations are variants of ectomycorrhiza found in certain plants in the Ericaceae characterised by hyphal coils in epidermal cells . The mycorrhiza formed by L. deterrimus on both bearberry and Norway spruce show typical features such as a hyphal mantle and a Hartig net ; the distinguishing characteristic between the mycorrhizal symbioses with the different hosts is that the hyphae penetrate the epidermal cells of bearberry , although there are also some differences in the form of the Hartig net , branching pattern , and colour . Although bearberry has been shown to form mycorrhiza with a wide range of fungi both in the field and in laboratory experiments , it had never previously been known to form mycorrhiza with fungi thought to be strictly host @-@ specific . Bearberry may function as a nurse plant to help re @-@ establish Norway spruce in deforested areas . 
