21st Century Guidebook to Fungi

In this chapter we will give you an overview of the organisms that make up Kingdom Fungi. We'll try to emphasise a more ecosystem-oriented approach because we want to avoid rambling taxonomy-driven species lists, but there may be as many as 1.5 million species of fungi currently present on Earth (see below), so we need to know some by name and understand the natural classification of fungi. A natural classification is the arrangement of organisms into groups on the basis of their evolutionary relationships.

To begin with we will describe enough of the taxonomic structure to provide a foundation for understanding the breadth of the group we are studying, and the major phyla that make up the kingdom: Chytridiomycota, Blastocladiomycota, Glomeromycota, Microsporidia (for which see Section 16.2), Zygomycota, Ascomycota and the Basidiomycota. We will then discuss what the word (or, better, concept) ‘species’ means in fungi and the ways in which a fungal species might be defined. In the final sections of the chapter we will examine those fungus-like organisms, which we call the ‘untrue fungi’, and which have some of the characteristics of fungi without being closely related in an evolutionary sense. In our final section we draw a few key aspects about fungi in the natural environment and in their natural communities from this overview of Kingdom Fungi that we will develop more fully in later chapters about ecosystem mycology.