areolate
Lichens are composite organisms made up of multiple species: a fungal partner, one or more photosynthetic partners, and sometimes a basidiomycete yeast. They are regularly grouped by their external appearance – a characteristic known as their ...
crustose
Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks and ...
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.mesic to arid habitats.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Acarospora strigata, Lichen Flora of the Greater Sonoran Desert Region. Vol 3, Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001 /ref> It is brown but may appear white or pale gray if it is covered in a
pruina Pruinescence , or pruinosity, is a "frosted" or dusty-looking coating on top of a surface. It may also be called a pruina (plural: ''pruinae''), from the Latin word for hoarfrost. The adjectival form is pruinose .
Entomology
In insects, a "blo ...
. The lichen is common in southwestern deserts of North America.
Areolas (from tiny to 3mm) surrounding dark reddish-brown to black
apothecia
An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...
are both highly variable in shape and size, and variable in size relative to each other. Measuring 0.1–1 mm, the apothecia range in size from small dots on the areolas to almost as wide as the areola.Lichen Flora of the Greater Sonoran Desert Region. Vol 3, Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001 /ref> They can be pointlike to round, polygonal to star-shaped, stellate radiating fissures, and one to many per areola. The lichen as a whole can thus appear as a collection of contiguous light rimmed dark circular forms, to a collection of whitish warts with dark dots.
Areoles may be cracked on the surface, especially toward the apothecia.
Lichen spot test
A spot test in lichenology is a spot analysis used to help identify lichens. It is performed by placing a drop of a chemical on different parts of the lichen and noting the colour change (or lack thereof) associated with application of the chemical ...