lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. /ref> One variety that grows in northern
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
is brilliant red. It is ( monophyllous) with a single 1 – 5 cm flattish leaf-like cap on top of an anchoring stem ( umbilicate). The leaflike top is smooth with some lobes, roughly circular, thin, and brittle.
The lower surface is light gray to light brown. It has up to 2.5 mm black circular to slightly polygonal spots that are the fruiting bodies ( apothecia), slightly sunken into the main nonfruiting body part (
thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...
). It grows on siliceous boulders in very dry climates of western North and South America, where it is usually the most common member of its genus.