Milkcaps belong to several genera (Lactarius, Lactifluus and partially Multifurca) in the family Russulaceae within the Basidiomycetes. They exude a milky fluid or latex when bruised and many of them are edible, though some are not very tasty.
This study focusses on the genus Lactarius, which has a worldwide distribution and about 450 species have been described, but we estimate the real diversity to be closer to 1000 species. They live in an obligate, mutualistic symbiosis with trees and shrubs and via the ectomycorrhized roots of their plant hosts, water and minerals are exchanged against carbohydrates. The most comprehensive molecular phylogenies of Lactarius that have up to now been published, comprise only a fraction of the species that have been described. The aim is to understand better the worldwide diversification and historical biogeography of the genus Lactarius. This research is based on a global sample of morphologically and molecularly well-documented collections, which will allows us to translate phylogenetic results into a stable systematic framework.