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Crustose lichens on a wall Growth of crustose lichen on a tree trunk. 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 ...
With the exception of calicioid lichens, lichen growth forms are based on the appearance of the thallus, which is the vegetative (non-reproductive) part of the lichen. [5] In most species, this form is determined by the lichen's fungal partner, though in a small number, it is instead the alga or cyanobacteria (the lichen's photosynthetic ...
Lichen growth forms are used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves (foliose lichens); others cover the substrate like a crust (crustose lichens) (illustration, right), others such as the genus Ramalina adopt shrubby forms (fruticose lichens ...
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]
Roccellaceae species have thalli (the main body of the lichen) ranging in form from crust-lie to bush-like . Crustose forms are often also byssoid (wispy, like teased wool). [1] The ascomata (spore-producing structures) are typically apotheciate (open, disc-like) or lirellate (elongated, slit-like).
Buellia frigida is a crustose lichen (sometimes placodioid) with a variable thallus size, more or less circular in outline. It has a diameter of up to 7 cm (2 + 3 ⁄ 4 in), although it is often much smaller.
In squamulose lichens the part of the lichen thallus that is not attached to the substrate may also appear leafy. But these leafy parts lack a lower cortex, which distinguishes crustose and squamulose lichens from foliose lichens. [44] Conversely, foliose lichens may appear flattened against the substrate like a crustose lichen, but most of the ...
Cryptothecia rubrocincta is a crustose lichen, because it grows in the form of a surface crust. The thallus, or body of the lichen is spread out flat and can be either tightly to loosely attached to the growing surface. It is 0.15–0.30 mm thick, and can be smooth, or have low radiating ridges.