Leaf spot fungus

A number of fungi are found on living leaves and some are obligatory leaf parasites. These fungi cause a variety of spots or other blemishes on leaves. The phrase  ‘leaf spot fungus’ is beautifully descriptive but it is not a precise taxonomic term since the fungi involved belong to diverse families.

They are classed as ‘local native’ on Canberra Nature Map but that is only because it is necessary to choose just one conservation level. It is undoubtedly the case that introduced species, naturally widespread species and endemic species occur in our region.

Look-alikes

Living leaves are also host to galls and insects (e.g. leaf miners) and when galls are minute or insect damage is very minor, such phenomena might be mistaken as fungal.

A great diversity of leaf-inhabiting lichens is found in humid areas (in particular the tropics and sub-tropics or rainforests in temperate areas). Here are some examples:

http://www.cpbr.gov.au/lichen/photos-captions/byssoloma-leaf-f-347.html

http://www.cpbr.gov.au/lichen/photos-captions/sporopodium-vezdeanum-f-392.html

http://www.cpbr.gov.au/lichen/photos-captions/strigula-smaragdula-f-334.html

http://www.cpbr.gov.au/lichen/photos-captions/strigula-subtilissimaf-336.html

Algae are also found on leaves in such areas and, when not green, might be mistaken for fungi.