Collema
| Collema | ||||||||||||
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Collema cristatum |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Collema | ||||||||||||
| ( L. ) Weber ex FH Wigg. |
Collema or glue lichen is a genus of lichen-forming tubular fungi . 80 species are known worldwide, 25 of which grow in Germany.
description
Collema species are dark brown to black leaf lichens. When dry, the bearings are brittle, but swell strongly when moistened and then have a gelatinous consistency. Cyanobacteria of the genus Nostoc occur as photobionts . If apothecia ( fruiting bodies ) appear, these are red to dark brown, mostly recessed, bordered discs. Many species are usually sterile and develop isidia , which are used for vegetative reproduction . The lichens are attached to the substrate with adhesives, only rarely with rhizines.
Location
The species represented in Central Europe grow on tree bark, soil and rock. The epiphytic representatives live on deciduous trees with sub-neutral bark, sometimes in warm, winter-mild locations. In some cases, humid, oceanic, mostly extremely precipitation-rich mountain areas are settled.
Rock-dwelling Collema species typically colonize light-open (often sunny) locations that remain soaked for some time after rainfall. Under these conditions, Collema callopismum , Collema cristatum , Collema fuscovirens , Collema multipartum and Collema polycarpon also colonize limestone rocks.
Danger
All species that grow on bark are partly threatened with extinction, partly already extinct. This is apparently based on a particularly low resistance to sulfur dioxide and a decrease in the pH of rainwater. Only Collema flaccidum , which also grows on silicate rock, does not react so extremely.
literature
- Wirth, Volkmar: Die Lichen Baden-Württemberg , Stuttgart 1995, ISBN 3-8001-3325-3
