Crustose Rock & Bark Lichen Photos
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Crustose Rock & Bark Lichens
In Cuyamaca State Park, San Diego County

Lecanora mellea. A crustose, chinky-lobate rock lichen with a shiny, cinnamon-brown, marginally-lobate thallus. The apothecia (red arrow) are lecanorine with a thalline rim containing algal cells. Dimelaena thysanota also has a brown thallus that is marginally-lobed and more distinctly areolate. The latter species has lecanorine apothecia with black hymenial disks. The colorless spores of L. mellea are small (less than 20 um) and 8 per ascus, unlike the spores of Dimelaena which are brown and 2-celled.


Ochrolechia oregonensis. A crustose lichen forming pale gray patches on the bark of white fir (Abies concolor). The apothecia are conspicuous (1-3 mm) with a lecanorine margin (thalline rim with algae). Apothecial disks are tan-colored with 8 colorless spores per ascus. The ascus is relatively large compared with other species. At 400x magnification, one ascus fills the entire field of view of a compound microscope. O. subpallescens typically grows on the bark of deciduous trees. The early red dye "cudbear" is from O. tartarea.


Diploschistes actinostomus. This gray, crustose rock lichen superficially resembles Aspicilia. It has large muriform spores typical of the genus Diploschistes.


Dimelaena thysanota. A brown, marginally-lobate crustose rock lichen (lobate margin is shown by red arrow). The apothecia are numerous with thalline rim and black hymenial disk. Spores are brown, 2-celled, 8 per ascus. The medulla is K- (D. californica K+ red). A common lichen on boulders with Lecidea atrobrunnea.


Grayish-brown Aspicilia cuprea growing on a boulder at Cuyamaca State Park. The thallus is areolate, divided into many sections called areoles. A black lichenicolous fungus (Lichenochora verrucicola) is parasitic on the lichen thallus. The dark mass (called a gall) contains several perithecia. The "eye" of an ordinary sewing needle is shown as a size relationship. It was placed next to the fungus, not someone's misplaced sewing needle that just happened to be in the picture. Aspicilia cinerea is another common, gray crustose species that appears like gray paint on granitic boulders.

See Straight Pin & Sewing Needle Used In Wayne's Word Articles


Trepeliopsis flexuosa. A common crustose lichen with a greenish, granular thallus and dark apothecia. It commonly grows on dead wood in the forest. T. granulosa is similar, but has a greenish-gray thallus with pinkish or brownish apothecia.


Images Of Desert Varnish And Rock Lichens:

References:

  1. Armstrong, W.P. 2001. "Lichens of Palomar Mountain." Wayne's Word: 27 Oct 2003. http://waynesword.palomar.edu/lichpal1.htm (Accessed on-line 27 October 2003).

  2. Brodo, I.M., S.D. Sharnoff and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven & London.

  3. Nash, T.H. III, B.D. Ryan, C. Gries and F. Bungartz. 2002. Lichen Flora of the Greater Sonoran Desert Region. Volume I. Lichens Unlimited, Arizona State University, Tempe.


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