Map lichen (Rhizocarpon geographicum) on rock
Map lichen (Rhizocarpon geographicum) on rock The European Space Agency has discovered that lichens can survive unprotected in space. In an experiment led by Leopoldo Sancho from the Complutense University of Madrid, two species of lichen—Rhizocarpon geographicum and Xanthoria elegans—were sealed in a capsule and launched on a Russian Soyuz rocket on 31 May 2005. Once in orbit the capsules were opened and the lichens were directly exposed to the vacuum of space with its widely fluctuating temperatures and cosmic radiation. After 15 days the lichens were brought back to earth and were found to be in full health with no discernible damage from their time in orbit. Under magnification, a section through a typical foliose lichen thallus reveals four layers of interlaced fungal filaments. The uppermost layer is formed by densely agglutinated fungal hyphae building a protective outer layer called the cortex, which can reach several hundred μm in thickness.[20] This cortex may be further topped by an epicortex μm thick in some Parmeliaceae, which may be with or without pores, and is secreted by cells—it is not itself cellular.[20] In lichens that include both green algal and cyanobacterial symbionts, the cyanobacteria may be held on the upper or lower surface in small pustules called cephalodia. Beneath the upper cortex is an algal layer composed of algal cells embedded in rather densely interwoven fungal hyphae. Each cell or group of cells of the photobiont is usually individually wrapped by hyphae, and in some cases penetrated by an haustorium. Beneath this algal layer is a third layer of loosely interwoven fungal hyphae without algal cells. This layer is called the medulla. Beneath the medulla, the bottom surface resembles the upper surface and is called the lower cortex, again consisting of densely packed fungal hyphae. The lower cortex often bears rootlike fungal structures known as rhizines, which serve to attach the thallus to the substrate on which it grows.
Size: 4287px × 2848px
Location: Map Lichen Beer beach Dorset England United Kingdom
Photo credit: © Roland Pargeter / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: algal, compatible, dispersal, fungal, fungi, fusion, lichen, manner, map, meet, meiosis., partner, producing, reproduce, result, rock, sexual, sexually, spores, typical
