A single head-sized rock is like a colourful miniature garden. Measuring just a few millimetres, the fragile orange-red fingers of the Namib Sun (Caloplaca elegantissima) seem to cling to the stone. The Lüderitz Cobblestone lichen (Acarospora luederitzensis) adapts in a yellow mosaic pattern to the uneven surface. Next to it, the grey Herero lichen (Santessonia hereroensis) looks like a small leafless shrub, surrounded by Lecanora panis-erucae, a rim lichen species with the appearance of white gravel. On the far side, a rampantly growing miniature shrub with large leaves: the foliose Walter’s lichen (Xanthoparmelia walteri). The ‘leaves’ are a light green and white on the inside and a very dark green, almost black, on the outside. When it has absorbed enough moisture, the whole lichen is soft, but as soon as the moisture evaporates in the sunshine the ‘leaves’ become hard and fragile. There are ten or twelve different lichens on this stone, and the same number on all the others nearby.

Lichen
The foliose Walter’s lichen (Xanthoparmelia walteri) is found throughout the Namib Desert and the Northern Cape Province of South Africa, where it grows on rocks and pebbles. In the Namib it occurs up to 40 km from the coast.

The vast gravel plains just north of Wlotzkasbaken sport an orange shimmer. A closer look reveals the fruticose Cape Hair lichen (Teloschistis capensis) by their thousands. Taking an even closer look, you will notice that light green hair-like pieces of Ramalina angulosa are partly entangled in the yellow Cape Hair. Various crustose lichens can be seen on the small stones next to it. In this part of the Namib Desert several square kilometres are covered with lichen.

Lichens are not plants but a symbiosis of tubular mushrooms and blue-green algae. They only exist because of the mutually advantageous relationship between the two living organisms. Lichen is classified into crustose, foliose and fruticose species. Professor Volkmar Wirth, an experienced lichenologist and author of the book Lichens of the Namib Desert – A guide to their identification, says that “categorisation is an easy way to describe the different shapes of lichen, but all their transitions and forms make it is difficult to apply these terms”. According to him there are 200 to 250 species in the Namib Desert (depending on where the border of the Namib is drawn) and more than 1,000 species are probably found in the whole of Namibia. A very large number of species has not yet been identified. Professor Wirth has been to Namibia nine times since 1986 for research on lichen. He says that he has encountered at least ten species that so far he has been unable to identify.

Lichen
The Herero lichen (Santessonia hereroensis) grows on pebbles all over the Namib Desert and in the Northern Cape Province.

The identification of lichen is not an easy task, as it often requires an analysis of the substances and microscopic examinations. Professor Wirth says that even the knowledge on some of the identified species needs improvement and further clarification. For example, according to molecular phylogenetic studies there are two types of Ramalina angulosa. Most of the scientifically described lichens in the Namib Desert do not even have English or German common names.

Countless species still have to be discovered and researched in Skeleton Coast National Park, Dorob National Park, Namib-Naukluft National Park and Sperrgebiet National Park. We have already destroyed many lichens – be it out of ignorance or recklessness – by driving all over the desert with off-road vehicles, instead of sticking to existing and well-frequented tracks. It takes decades for lichens to settle, and they grow only a few millimetres a year.

Author: Dirk Heinrich

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