My speculations about the origin of lichens (“It takes two to tango …”) has led me to one final post about Malham’s lichens. Tucked into a shady cranny at the base of the trunk of a large tree was grey-green powdery lichen called Lepraria which represents one of the most primitive types of lichen: little more than some algae amongst a tangle of fungal hyphae.
Lepraria sp at the base of a beech tree in the grounds of Malham Tarn field centre, April 2014. Inset left: fungal hyphae and inset top right, algal cells. Scale bar: 10 micrometres (1/100th of a millimetre)
It was not easy to get an image showing both fungi and algae at the same time. Scraping the lichen off the bark and onto a microscope slide resulted in small pieces of bark and soil being mixed in with the lichen itself. Some could be teased apart but many clumps were too dense to photograph. You can see some of these dense particles in the background of the image of hyphae. However, looking at these primitive lichens does give you some idea of the starting point in the gradual evolution of the complex structures that we saw in “More about Malham’s lichens”.