[2] About 140 Phoma taxa have been defined and recognized[3] which may be divided into two large groups: (i) plurivorous fungi, generally saprobic or weakly parasitic, mainly from temperate regions in Eurasia, but occasionally also found in other parts of the world (including areas with cool or warm climates); and (ii) specific pathogens of cultivated plants.

[4] However other estimates place the number of taxa closer to 3000, making it one of the largest fungal genera.

[5] Traditionally nine sections (Phoma, Heterospora, Macrospora, Paraphoma, Peyronellaea, Phyllostictoides, Pilosa, Plenodomus and Sclerophomella) as described by Boerema (1997) have been recognised on morphological grounds.

[5] However phylogenetic studies suggest the genus is highly polyphyletic containing six distinct clades.

[5] Consequently, there is little justification for retaining the sections, a number of which such as Peyronellaea are now elevated to genus rank, within Didymellaceae.