A division containing the *lichens
. It was created before it was realized that lichens are symbiotic associations between fungi and algae. Now lichens are considered to be fungi especially adapted to obtain food from algae living within their tissues. They are consequently classified in the appropriate rank of the Eumycota, according to the nature of the fungus. However, since the affinities of many lichens are still unknown, the division Lichenes is maintained for convenience. It is divided into the three classes Ascolichenes (see Lecanorales
), Basidiolichenes, and Lichenes Imperfecti. The Basidiolichenes, e.g. Cora and Dictyonema, are limited to the tropics. They superficially resemble bracket fungi and produce basidia in an even layer on the undersurface of the thallus. The fungi involved are considered closely related to members of the Agaricales. The Lichenes Imperfecti, which contain imperfect fungi, include such common genera as Lepraria and Crocynia. Reproduction in such lichens is wholly by dispersal of fragments of the thallus and asexual conidiophores are not formed.