Rhizocarpon geographicum (L.) DC. Yellow map lichen, world map lichen
This is one of several "map lichens," so-called because at close range, each tiny lichen is bordered by black spores that resemble borders on a map. Yellow map lichen is common in cool forests, such as the Sierra Nevada mountains, northern Maine, Canada, Greenland, Iceland, and Siberia. Closer to the equator, it is found at progressively higher elevations. Although it can withstand two weeks of exposure to space, it is sensitive to pollution, and fares best in low pollution environments. Identification: The pale yellow patches with black spore-lined edges do not closely resemble other lichens. Yellow map lichen is crustose, forming a thin, tightly attached surface on rocks. Online References:
Stephen and Sylvia Sharnoff's lichen.com site Botanyphoto.botanicalgarden.ubc.ca Alan Silverside's Lichen Pages on LastDragon.org The Toolik↔Arctic Geobotanical Atlas References:
Walewski, Joe, Lichens of the North Woods, Kollath+Stensaas Publishing, 2007, p. 66
Rhizocarpon geographicum description by Thomas H. Kent, last updated 25 May 2020. |
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