Mycorrhization of fossil and living plants

The widespread mycorrhization together with the fossil record indicate that plants and fungi have evolved in mycorrhizal relationship since the colonization of land by early plants. In living plants most mycorrhizal symbioses are mutualistic associations in which fungus and plant exchange metabolites and nutrients required for their growth and survival. They concern either the gametophyte and/or the sporophyte of most embryophytes. A new nomenclature is suggested to define two types of mycorrhizae: (1) paramycorrhizae for the colonization of thalli and shoot systems: (2) eumycorrhizae for the colonization of root systems. The aim of this paper is to show the mycorrhizal status in relation with the various clades of embryophytes by considering both fossil and living plants and to develop the implications of mycorrhizal symbiosis in the colonization of land by early plants and in the evolution of plants.