Foliicolous lichens are lichens that grow on the living leaves
of angiosperms, fern fonds, phyllodes, phylloclades and young
bamboo culms. Generally they occur on the leaves that shed off in 2-5 years or stayed longer (e.g. Agave and palm leaves), except few
taxa which were found to grow on annually deciduous leaves.
Majority of the foliicolous lichens were found on the upper side of
the leaves i.e. epiphyllous, but few also grow on the lower side i.e.
hypophyllous. Foliicolous lichens generally prefer growing over
leaves of lower branches which not only enjoyed thepartial shade of
the over growing branches but also had a more humidenvironment
than others. Based on their substrate specificity, they can be divided
into three groups:
1) Eufoliicolous lichens: they grow and reproduce entirely
on the leaves and have a crustose thallus that is tightly
adnate to the substrate.
2) Facultative foliicolous lichens: they usually grow on
barks, petioles and twigs but exceptionally on leaves.
3) Pseudofoliicolous (indifferent or ubiquitous) lichens:
besides growing on leaves they can grow on different
substrates, such as rock, bark, soil etc.
The diversity and density of foliicolous lichens isabundant in
the tropical rainforests of Central and South America, Africa and
Southeast Asia, due to availability of optimum temperature, humidy,
sunlight and shade throughout the year. Besides tropical rainforests,
they are also reported from subtropical and temperate rainforests
having humid areas, but the diversity and density in the subtropical
and temperate regions is less in comparison to tropical regions
because of lack of suitable macro- and micro- climatic conditions
responsible for the luxuriance growth of these lichens.
