Symbiotic fungi and algae of a special kind of plant. No roots, stems and leaves of differentiation, can live in various environments, known as the vegetable kingdom's pioneering vanguard. "Symbiotic fungi are mostly ascomycetes, basidiomycetes few are able to absorb water and inorganic salts, and coated algae; symbiotic algae mainly cyanobacteria and green algae, can carry out photosynthesis, create organic matter.
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No. 2
Symbiotic fungi and algae, a kind of special plants. No roots, stems and leaves of differentiation, can live in various environments, known as the "Flora of the pioneering vanguard." Symbiotic fungi are mostly ascomycetes, basidiomycetes few are able to absorb water and inorganic salts, and coated with algae; symbiotic algae, cyanobacteria and green algae, mainly, to carry out photosynthesis, manufacturing organic matter.
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The general characteristics of lichens (continuity)
1, lichens are symbiotic algae and fungi together complex organism. There is no differentiation of root, stem, simple, and perennial plants of the original implant. Between algae and fungi as long-term closer together and become a separate group of fixed organisms. It neither fungi in general, but also different from algae. And has a unique shape, structure, physiological and genetic characteristics. They are the result of the development and evolution of plants for many years. Therefore, the lichens treated as a separate door. The doors around the world about 500 genera and 25,000 species. Lichens, algae composition: mainly cyanobacteria and green algae. Cyanobacteria are mainly Nostoc, Chlorella algae are mainly Sphere. Fungi form lichens: Most ascomycetes, few are basidiomycetes. The fungi form lichens in many ways different from the general physical characteristics of fungi, especially called "lichen-type fungus." On fungi in lichens accounted for the main part of the structure. Lichens of the original form of implant is almost entirely determined by the symbiotic fungus. Algae, lichens distributed in the interior of cells to form a layer of algae or algal cell or a number of groups scattered hyphae. Algae, bacteria symbiotic relationship is this: photosynthesis of algae cells manufacturing plants throughout the lichens of organic nutrients, while the mycelium is absorb water and salts, to provide raw materials for the photosynthesis of algae, algal cells and to maintain a certain humidity, not dry death. Algae that form lichens bacteria symbiotic relationship of mutual benefit between. But the test was done, the lichens, algae, plants and fungi in the separation of culture and found that algae can live for a long time, while the fungus was starved to death. That fungi can not live alone, lichens, fungi must rely on the body of living algae. This is because, fungi and algae symbiosis long after the life of their own cells produce substances or enzymes has been changed.
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The form of lichen structure
(A) the form of lichen By growth form, the form of lichens can basically be divided into 3 types: 1, shell-like lichens: Lichens body is a shell with a variety of colors, seemed to hyphae closely linked with the matrix, and some hyphae also _insert_ed into the matrix. Therefore, the lichens and the matrix is difficult to peel. About all the lichen crust-like lichens 80%. Such as living in the tea stains on the clothes rock is (lecanora) and was born in the text on the bark clothing is (graphis). 2, leafy lichens: lichens flat, with dorsal and ventral of the points, was the leaf-shaped, surrounded by a flap-like lobes, the lower (ventral) to rhizoids or umbilical fixation on the base material, easy and matrix stripping. Such as life rolled on the grass, is clothing (peltigera), umbilical clothing is (umbilicaria) and born in May on a rock or tree bark clothing is (parmelia) (Figure). 3, branched lichens: lichens erect or drooping, dendritic or columnar, the majority of a branch, only the base attached to the substrate. If the litmus upright on the ground is (cladonia) and overhanging branches, was born in spruce, hemlock, fir branches on the genus Usnea (usnea) and so on. (Pictured) faster than the growth of branched shell lichen-like, leafy lichens much faster. Usnea spent a lot of clothes hanging in the trees territories will result in tree death. (According to another report: Usnea lichens are the main food of Yunnan snub-nosed monkey, the Yunnan golden monkey food one, and now may be a lot of extinction. (B) the construction of lichens Cross-section of the lichens, we can see its internal structure: General can be divided into the internal cortex, algal cell layer, medullary layer and lower cortex. Under the epithelium and cortex by hyphae form dense interwoven. Algal cells in lichens according to the distribution of the internal, usually in the structure, the lichens were divided into 2 types: 1, the different layers lichens: algae gathered in the epithelial cells under the formation of a layer of clear cell layer of algae. Medullary layer between the algae and in the cortical cell layer between the composition by a number of loose hyphae. Medullary layer with little or no algal cells. This structure is called "cross-layer lichen. Mei Yi is (parmelia) and centipedes clothes are (physcia). 2, the same layer lichens: in transverse section, under the epithelium there is no obvious single algal cell layer of algal cells in the pulp evenly distributed layer of hyphae. This structure was known as "lichen the same floor." Clothing such as cat ears are (leptogium). Leafy lichens lichens are generally different layers. Shell-like layer of lichens, mostly with lichens, crust-like lichens not in the cortical, medullary layer and the substrate directly. For the different layers branched lichens lichens. The internal structure was radiant, dense outer cortex, a thin layer of algal cells surrounded by axial medullary layer, or pulp layer is hollow. Some lichens have a variety of color, mainly by the composition of the hyphal cells in the cortex contains a lot of orange, yellow or other colors formed.
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The propagation of lichens
Breeding methods nutritious lichen reproduction and sexual reproduction. 1, vegetative propagation: the reproduction is the most common form. The fracture is mainly lichens, a lichens off (broken) split into several lobes, each lobe can develop into new individuals. 2, sexual reproduction: sexual reproduction for the lichens in the ascomycetes and basidiomycetes carried out. Produce ascospores or basidiospores. The former said ascomycetes lichens, covering most types of clothing; which said basidiomycete lichens, a small number. Ascomycete fruiting bodies formed by lichens are mostly ascus disk. Ascospores or basidiospores mature released, fell a suitable environment (with nutrients and algal cells), then the germination of algal cells to hyphae, algal cells and hyphae repeatedly split to form new lichens. Ascospores fall if there is no algae cells and no nutrients in the substrate, spore germination hyphae to die soon.
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The role of lichens in nature and economic significance
1, can secrete acid in lichen, corrosion rock, for weathering, the rock pioneer plant changes the soil. 2, litmus, Usnea, etc. can be used for medical purposes. 3, alpine and polar reindeer lichen communities is the main feed. 4, some lichens can extract natural dyes and chemical indicators, such as litmus paper. 5, can be used as indicator plants for monitoring air pollution. 6, a large number of Usnea lichens hanging from trees, the cold, spruce trees have a certain hazards.