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Usnea is a genus of fruticose lichens in the large family Parmeliaceae. The genus, which currently contains roughly 130 species, was established by Michel Adanson in 1763. Species in the genus grow like leafless mini- shrubs or tassels anchored on bark or twigs.
Its undifferentiated thallus is an irregular mix of fungal hyphae and scattered photobiont cells, lacking a cortex or any definable layers. [6] [47] Morphologically, it is the simplest growth form. [48] The cell walls of leprose lichens contain chemical compounds which make them hydrophobic, and thus largely water repellent. However, the lack ...
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 ...
The thallus is different from those of either the fungus or alga growing separately. The fungus surrounds the algal cells, often enclosing them within complex fungal tissues unique to lichen associations. In many species the fungus penetrates the algal cell wall, forming penetration pegs or haustoria similar to those produced by pathogenic fungi.
The Parmeliaceae is a large and diverse family of Lecanoromycetes.With over 2700 species [2] in 71 genera, it is the largest family of lichen-forming fungi.The most speciose genera in the family are the well-known groups: Xanthoparmelia (822 species), Usnea (355 species), Parmotrema (255 species), and Hypotrachyna (262 species).
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]
A fungus that lives within the thallus of a lichen without producing any visible symptoms of disease; these fungi are transmitted horizontally. [165] Lecidea laboriosa is an endolithic lichen; the thallus, hardly visible, grows under and around the rock crystals, while the apothecia are visible on the surface. endolith Also endolithic.
Download as PDF; Printable version; ... Diagram of a plant cell and its constituent organelles. --> ... An example of the template with all diagrams activated.