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Crustose lichens are lichens that form a crust which strongly adheres to the substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. [1] The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla.
A leprose lichen, which is typically considered to be a form of crustose lichen, is one with a powdery or dust-like appearance. Its undifferentiated thallus is an irregular mix of fungal hyphae and scattered photobiont cells, lacking a cortex or any definable layers.
Leprose lichens consist of crusts without a layered structure. [4] Crustose lichens have learned to adapt to their environment, with the shells helping with adaptation to dry and drought resistant climates. Crustose lichens have been found in deserts, ice free parts of Antarctica, and in the Alpine and Arctic regions. [5]
A fruticose lichen may have flattened "branches", appearing similar to a foliose lichen, but the underside of a leaf-like structure on a fruticose lichen is the same color as the top side. The leaf-like lobes of a foliose lichen may branch, giving the appearance of a fruticose lichen, but the underside will be a different color from the top side.
The lower cortex of foliose lichens often bears rootlike fungal structures known as rhizines, which serve to attach the thallus to the substrate on which it grows. Lichens also sometimes contain structures made from fungal metabolites, for example crustose lichens sometimes have a polysaccharide layer in the cortex. Although each lichen thallus ...
The thallus of this crustose lichen has a distinctive areolate structure, with the individual areoles varying considerably in their appearance. They typically range from 0.2–0.6(−1.2) mm in diameter, displaying an angular, irregular shape.
Buellia frigida is a species of saxicolous (rock-dwelling), crustose lichen in the family Caliciaceae. It was first described from samples collected from the British National Antarctic Expedition of 1901–1904. It is endemic to maritime and continental Antarctica, where it is common and widespread, at altitudes up to about 2,000 m (6,600 ft).
Usnea filipendula – one of about 20,000 described species of lichen. The following outline provides an overview of and topical guide to lichens.. Lichen – composite organism made up of multiple species – a fungal partner, one or more photosynthetic partners, which can be either green algae or cyanobacteria, and, in at least 52 genera of lichens, a yeast. [1]