Undifilum

Undifilum is a genus name that has appeared in mycological and plant-pathology literature to refer to a group of endophytic fungi associated with grasses. In older or informal classifications, Undifilum was used for systemic symbionts in the family Clavicipitaceae that colonize above- and below-ground tissues of grasses without causing obvious disease. Over the last two decades, molecular phylogenetics has prompted taxonomic revisions in this group, and several species previously placed in Undifilum have been reassigned to other genera such as Epichloë, Neotyphodium, or Balansia. As a result, the status of Undifilum as a distinct, currently accepted genus is contested, and many modern databases treat it as deprecated or as a synonym of related genera.

Biology and ecology: The organisms historically labeled Undifilum are endophytes living inside grass tissues. They typically form mutualistic relationships with their hosts, sometimes producing alkaloids or other metabolites that affect herbivore resistance, growth, or stress tolerance. The exact phenotype depends on the strain, host species, and environmental conditions, and some lineages can be asymptomatic or variably virulent.

Habitat and distribution: Endophytic in temperate grasses, particularly in agricultural and recreational grasses used for pastures and lawns. Reports have arisen from various regions where such grasses occur, though the name Undifilum is less commonly used in contemporary taxonomy.

Taxonomic notes: Index Fungorum and MycoBank provide records for Undifilum, but recent reviews prefer alternative genera for the species formerly assigned to it. Researchers rely on DNA sequence data (e.g., multi-locus phylogenies) to resolve placement within Clavicipitaceae.

See also: Epichloë, Neotyphodium, Balansia, grass endophytes.

References: MycoBank entry for Undifilum; reviews on Epichloë and Neotyphodium; taxonomic studies of Clavicipitaceae.