Fungus

Fungi is one of the five kingdoms in Linnaean Taxonomy. It contains the Phyla :

Phylum Chytridiomycota - of definite relationship to the fungi, but often placed among the Protista.
Phylum Zygomycota
Phylum Ascomycota
Phylum Basidiomycota
Phylum Deuteromycota: fungi of uncertain placement, grouped for convenience

Lichens are a long-standing symbiotic relationship, formed between a fungus and a green alga or a cyanobacterium. Lichens are named based on the fungal component, typically a member of the Ascomycota, rarely a member of the Basidiomycota. Some place lichens in their own phylum (Mycophycophyta) but this ignores the fact that the components belong in separate lineages.