What is a phylum?
Phylum
In biology, a phylum (/ˈfaɪləm/; plural: phyla) is a level of classification or taxonomic rank below Kingdom and above Class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent.[1][2][3] Depending on definitions, the animal kingdom Animalia or Metazoa contains approximately 35 phyla, the plant kingdom Plantae contains about 14, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta.
Cryptogam
Not all cryptogams are treated as part of the plant kingdom; the fungi, in particular, are regarded as a separate kingdom, more closely related to animals than plants, while blue-green algae are now regarded as a phylum of bacteria. Therefore, in contemporary plant systematics, "Cryptogamae" is not a taxonomically coherent group, but is cladistically polyphyletic. However, all organisms known as cryptogams belong to the field traditionally studied by botanists and the names of all cryptogams are regulated by the "International Code of Nomenclature for algae, fungi, and plants".