|
Rhizine
In lichens, rhizines are multicellular root-like structures arising mainly from the lower surface. A lichen with rhizines is termed rhizinate, while a lichen lacking rhizines is termed erhizinate. Rhizines serve only to anchor the lichen to their substrate; they do not absorb nutrients, as plant roots do. Characteristics of the rhizines are used to identify lichens, for example, whether they are dense or sparse, uniformly distributed or clumped in specific areas, and straight or branched. Only foliose lichens may possess rhizines, not crustose or fruticose lichens, which lack a lower cortex. Rhizohyphae are a type of attachment structure on some lichens. Rhizohyphae are more slender than rhizines and are one cell thick in diameter. Rhizohyphae often occur as a felt-like hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizoid
Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be unicellular or multicellular. Evolutionary development Plants originated in aquatic environments and gradually migrated to land during their long course of evolution. In water or near it, plants could absorb water from their surroundings, with no need for any special absorbing organ or tissue. Additionally, in the primitive states of plant development, tissue differentiation and division of labor were minimal, thus specialized water-absorbing tissue was not required. The development of specialized tissues to absorb water efficiently and anchor the plant body to the ground enabled the spread of plants onto land. Description Rhizoids absorb water mainly by capillary action in which water moves up between threads of rhizoids; this is in co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peltigera Praetextata-4
''Peltigera'' is a genus of approximately 100 species of foliose lichen, foliose lichens in the family (biology), family Peltigeraceae. Commonly known as the dog or pelt lichens, species of ''Peltigera'' are often terricolous lichen, terricolous (growing on soil), but can also occur on moss, trees, rocks, and many other in many parts of the world. Most species of ''Peltigera'' have the cyanobacterium ''Nostoc'' as the dominant Lichen, photobiont but some have the algae ''Coccomyxa.'' The presence of both a green alga and a cyanobacterium makes some tripartite; in this case they show cephalodium growths containing the third partner, ''Nostoc''. Because of their ability to nitrogen fixation, fix nitrogen from the atmosphere, such lichens are influential in soil composition and generation. Description Species of ''Peltigera'' are Foliose lichen, foliose, with broad lobed thallus, thalli. Although the size of the thalli is variable and species-dependent, in some species the thalli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichens
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), mutualistic relationship.Introduction to Lichens – An Alliance between Kingdoms . University of California Museum of Paleontology. . Lichens are the lifeform that first brought the term symbiosis (as ''Symbiotismus'') into biological context. Lichens have since been recognized as important actors in nutrient cycling and producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicellular Organism
A multicellular organism is an organism that consists of more than one cell (biology), cell, unlike unicellular organisms. All species of animals, Embryophyte, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social Amoeba, amoebae such as the genus ''Dictyostelium''. Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells. Colonial organisms are the result of many identical individuals joining together to form a colony (biology), colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular". There are also macroscopic organisms that are multinucleate though technically unicellular, such as the Xenophyophorea that can reach 20 cm. Evolutionary history ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root
In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the soil, but roots can also be aerial root, aerial or aerating, that is, growing up above the ground or especially above water. Function The major functions of roots are absorption of water, plant nutrition and anchoring of the plant body to the ground. Types of Roots (major rooting system) Plants exhibit two main root system types: ''taproot'' and ''fibrous'', with variations like adventitious, aerial, and buttress roots, each serving specific functions. Taproot System Characterized by a single, main root growing vertically downward, with smaller lateral roots branching off. Examples. Dandelions, carrots, and many dicot plants. Fibrous RootSystem Consists of a network of thin, branching roots that spread out from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nutrient
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted into smaller molecules in the process of releasing energy such as for carbohydrates, lipids, proteins and fermentation products ( ethanol or vinegar) leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root
In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the soil, but roots can also be aerial root, aerial or aerating, that is, growing up above the ground or especially above water. Function The major functions of roots are absorption of water, plant nutrition and anchoring of the plant body to the ground. Types of Roots (major rooting system) Plants exhibit two main root system types: ''taproot'' and ''fibrous'', with variations like adventitious, aerial, and buttress roots, each serving specific functions. Taproot System Characterized by a single, main root growing vertically downward, with smaller lateral roots branching off. Examples. Dandelions, carrots, and many dicot plants. Fibrous RootSystem Consists of a network of thin, branching roots that spread out from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foliose Lichen
A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common growth forms of lichens. It typically has distinct upper and lower surfaces, each of which is usually covered with a cortex; some, however, lack a lower cortex. The photobiont layer lies just below the upper cortex. Where present, the lower cortex is usually dark (sometimes even black), but occasionally white. Foliose lichens are attached to their substrate either by hyphae extending from the cortex or , or by root-like structures called . The latter, which are found only in foliose lichens, come in a variety of shapes, the specifics of which can aid in species identification. Some foliose lichens attach only at a single stout peg called a , typically located near the lichen's centre. Lichens with this structure are called "umbilicate". In general, medium to large epiphytic foliose lichens are moderately sensitive to air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustose
Crustose is a Habit (biology), habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the Substrate (biology), substrates at all points. ''Crustose'' is found on Rock (geology), rocks and Bark (botany), tree bark. Some species of marine algae of the Rhodophyta, in particular members of the Order (biology), order Corallinales, Family (biology), family Corallinaceae, subfamily Melobesioideae with cell walls containing calcium carbonate grow to great depths in the intertidal zone, forming crusts on various substrates. The substrate can be rocks throughout the intertidal zone, or, as in the case of the Corallinales, reef-building coral reef, corals, and other living organisms including plants, such as mangroves and animals such as shelled molluscs. The coralline red algae are major members of coral reef communities, cementing the corals together with their crusts. Among the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fruticose
A fruticose lichen is a form of lichen fungi that is characterized by a coral-like shrubby or bushy lichen growth forms, growth structure. It is formed from a symbiotic relationship of a photobiont such as green algae or less commonly cyanobacteria and one, two or more mycobionts. Fruticose lichens are not a monophyletic and holophyletic lineage, but are a form encountered in many classes. Fruticose lichens have a complex vegetation structure, and are characterized by an ascending, bushy or pendulous appearance. As with other lichens, many fruticose lichens can endure high degrees of desiccation. They grow slowly and often occur in habitats such as on tree barks, on rock surfaces and on soils in the Arctic and mountain regions. Characteristics Characteristic of fruticose lichen is the shape of the thallus. Like crustose lichen, fruticose lichen is composed of a holdfast which will act as an anchor for the lichen to grow in rock fissures, over loose sand or soil. Growth and struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortex (botany)
In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. The outer cortical cells often acquire irregularly thickened cell walls, and are called collenchyma cells. Plants Stems and branches In the three dimensional structure of herbaceous stems, the epidermis, cortex and vascular cambium form concentric cylinders around the inner cylindrical core of pith. Some of the outer cortical cells may contain chloroplasts, giving them a green color. They can therefore produce simple carbohydrates through photosynthesis. In woody plants, the cortex is located between the periderm (bark) and the vascular tissue ( phloem, in particular). It is responsible for the transportation of materials into the central cylinder of the root through diffusion and ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypha
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or more cells surrounded by a tubular cell wall. In most fungi, hyphae are divided into cells by internal cross-walls called "septa" (singular septum). Septa are usually perforated by pores large enough for ribosomes, mitochondria, and sometimes nuclei to flow between cells. The major structural polymer in fungal cell walls is typically chitin, in contrast to plants and oomycetes that have cellulosic cell walls. Some fungi have aseptate hyphae, meaning their hyphae are not partitioned by septa. Hyphae have an average diameter of 4–6 μm. Growth Hyphae grow at their tips. During tip growth, cell walls are extended by the external assembly and polymerization of cell wall components, and the internal production of new cell membrane. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
