How lichens multiply and disperse
The upper surface of many lichens bears special structures which appear as miniature jam tarts, delicate cups, or tiny volcanoes with a minute pore at the tip. Some are brightly coloured, others more muted, and many are black. A special group of crustose lichens found on the smooth bark of hazel, rowan, holly and ash (particularly in the west) are known as 'script lichens' as they have short, scribble-like lines scattered over their surface. All these structures are known as 'fruit bodies' as they forcibly discharge tiny spores to a height of a few millimeters where they have a good chance of becoming airborne.
Reproduction by spores is a risky business as, on landing and germination, they need to meet the right algal partner before they can form a new lichen.
Many lichens increase their chance of successful reproduction by producing special parts that become detached and grow into a new plant (propagules) containing both alga and fungus. The most common are powdery structures (soralia) that develop as pustules on the upper surface. These release small clumps of algal cells (soredia) held together by a web of fungal threads (hyphae). The other structures for vegetative reproduction, also unique to lichens, are isidia. These are fragile, peg-like outgrowths on the upper surface which contain both partners. Numerous lichen isidia and soredia are picked up following stormy nights by pollen-sampling equipment run for hay-fever sufferers in a rooftop location in Edinburgh
If you look through a hand lens you will see that the upper surfaces of lichens with their varied fruit bodies, soralia, isidia and range of hues look extremely beautiful.