Crustose Lichen in Jotunheimen, Norway
November 17, 2007
Different lichen species have different growth rates, and even individuals of the same species have different rates in different locales. Growth rates have been measured ranging from fractions of mm/year for most crustose species to over 10 cm/year for a few fruticose species. For crustose species on the rocks of Jotunheimen, Norway, where this photo was taken, a ballpark estimate of the current radial growth rate is 0.5 mm/year (0.02 inches per year). The exceptionally round and large specimen shown here measures about 40 cm (15.5 inches) in diameter. Thus, this organism may have been perched on the pictured rock surface for at least 400 years and possibly 800 years! Photo taken on June 29, 2007.