Collema tenax

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Collema tenax
Collema tenax Jymm.jpg

Apparently Secure (NatureServe)
Scientific classification
C. tenax
Binomial name
Collema tenax

Collema tenax is a species of lichen known by the common names jelly lichen, black lichen, and desert lichen. It occurs in Arctic and temperate regions in the Northern Hemisphere.[1] It is very common in North America, and it is present in Europe, Asia, and Africa. It is the most widely distributed Collema.[2]

This lichen has a thick black or dark green gelatinous thallus which is variable in size. It is generally 1 to 3 centimeters wide.[2] It contains a symbiont, the cyanobacterium Nostoc commune. It reproduces when pieces of the thallus break off, or when isidia, soredia, and apothecia are produced.[1] It is tolerant of desiccation, shrinking when dry and swelling up when water is present.[2]

This lichen is terricolous, growing on the soil surface. It is an indicator of basic soils, and is often found on gypsum-rich and other calcareous soils. It is a common component of cryptobiotic soil crusts, for example, in the dry regions of the western United States. It fixes nitrogen, increasing the nitrogen levels in the soil.[1]


  1. ^ a b c Matthews, Robin F. 1993. Collema tenax. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
  2. ^ a b c Lange, O. L., et al. (1998). Photosynthesis of the cyanobacterial soil-crust lichen Collema tenax from arid lands in southern Utah, USA: Role of water content on light and temperature responses of CO2 exchange.[permanent dead link] Functional Ecology 12 195-202.

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