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Hydathodes
A hydathode is a type of pore, commonly found in angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plants such as ''Ranunculus fluitans'' as well as herbaceous plants of drier habitats such as '' Campanula rotundifolia''. They are connected to the plant vascular system by a vascular bundle. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species. Hydathodes are made of a group of living cells with numerous intercellular spaces filled with water, but few or no chloroplasts, and represent modified bundle-ends. These cells (called ''epithem cells'') open out into one or more sub-epidermal chambers. These, in turn, communicate with the exterior through an open water stoma or open pore. The water stoma structurally resembles an ordinary stoma, but is usually larger and has lost the power of movement. Hy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Section Of Hydatoda In The Leaf Of Primula Sinensis
A, or a, is the first letter and the first vowel of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English grammar, " a", and its variant " an", are indefinite articles. History The earliest certain ancestor of "A" is aleph (also written 'aleph), the first letter of the Phoenician alphabet, which consisted entirely of consonants (for that reason, it is also called an abjad to distinguish it f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stoma
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the stomatal opening. The term is usually used collectively to refer to the entire stomatal complex, consisting of the paired guard cells and the pore itself, which is referred to as the stomatal aperture. Air, containing oxygen, which is used in respiration, and carbon dioxide, which is used in photosynthesis, passes through stomata by gaseous diffusion. Water vapour diffuses through the stomata into the atmosphere in a process called transpiration. Stomata are present in the sporophyte generation of all land plant groups except liverworts. In vascular plants the number, size and distribution of stomata varies widely. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vascular Plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue (the phloem) to conduct products of photosynthesis. Vascular plants include the clubmosses, horsetails, ferns, gymnosperms (including conifers), and angiosperms (flowering plants). Scientific names for the group include Tracheophyta, Tracheobionta and Equisetopsida ''sensu lato''. Some early land plants (the rhyniophytes) had less developed vascular tissue; the term eutracheophyte has been used for all other vascular plants, including all living ones. Historically, vascular plants were known as "higher plants", as it was believed that they were further evolved than other plants due to being more complex organisms. However, this is an antiquated remnant of the obsolete scala naturae, and the term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transpiration
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. Leaf surfaces are dotted with pores called stomata (singular "stoma"), and in most plants they are more numerous on the undersides of the foliage. The stomata are bordered by guard cells and their stomatal accessory cells (together known as stomatal complex) that open and close the pore. Transpiration occurs through the stomatal apertures, and can be thought of as a necessary "cost" associated with the opening of the stomata to allow the diffusion of carbon dioxide gas from the air for photosynthesis. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients and water from roots to shoots. Two major factors i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parenchyma
Parenchyma () is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology it is the name for the tissue that fills the interior of flatworms. Etymology The term ''parenchyma'' is New Latin from the word παρέγχυμα ''parenchyma'' meaning 'visceral flesh', and from παρεγχεῖν ''parenchyma'' meaning 'to pour in' from παρα- ''para-'' 'beside' + ἐν ''en-'' 'in' + χεῖν ''chyma'' 'to pour'. Originally, Erasistratus and other anatomists used it to refer to certain human tissues. Later, it was also applied to plant tissues by Nehemiah Grew. Structure The parenchyma is the ''functional'' parts of an organ (anatomy), organ, or of a structure such as a tumour in the body. This is in contrast to the Stroma (animal tissue), stroma, which refers to the ''structural'' tissue of organs or of structures, namely, the connective tissues. Brain The brain parenchyma refers to the functional tissue in the brain that is made up of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichome
Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant is an indumentum, and the surface bearing them is said to be pubescent. Algal trichomes Certain, usually filamentous, algae have the terminal cell produced into an elongate hair-like structure called a trichome. The same term is applied to such structures in some cyanobacteria, such as '' Spirulina'' and ''Oscillatoria''. The trichomes of cyanobacteria may be unsheathed, as in ''Oscillatoria'', or sheathed, as in ''Calothrix''. These structures play an important role in preventing soil erosion, particularly in cold desert climates. The filamentous sheaths form a persistent sticky network that helps maintain soil structure. Plant trichomes Plant trichomes have many different features that vary between both species of plants an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gland
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure Development Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may in the beginning possess a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated. As growth proceeds, the column of cells may split or give off offshoots, in which case a compound gland is formed. In many glands, the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another, but in one instance, the liver, this does occur when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halophyte
A halophyte is a salt-tolerant plant that grows in soil or waters of high salinity, coming into contact with saline water through its roots or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs and seashores. The word derives from Ancient Greek ἅλας (halas) 'salt' and φυτόν (phyton) 'plant'. Halophytes have different anatomy, physiology and biochemistry than glycophytes.Physiology of halophytes, T. J. FLOWERS, Plant and Soil 89, 41-56 (1985) An example of a halophyte is the salt marsh grass ''Spartina alterniflora'' (smooth cordgrass). Relatively few plant species are halophytes—perhaps only 2% of all plant species. Information about many of the earth's halophytes can be found in thehalophdatabase. The large majority of plant species are glycophytes, which are not salt-tolerant and are damaged fairly easily by high salinity. Classification Halophytes can be classified in many ways. According to Stocker (1933), it is mainly of 3 kin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root Pressure
Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day. When transpiration is high, xylem sap is usually under tension, rather than under pressure, due to transpirational pull. At night in some plants, root pressure causes guttation or exudation of drops of xylem sap from the tips or edges of leaves. Root pressure is studied by removing the shoot of a plant near the soil level. Xylem sap will exude from the cut stem for hours or days due to root pressure. If a pressure gauge is attached to the cut stem, the root pressure can be measured. Root pressure is caused by active distribution of mineral nutrient ions into the root xylem. Without transpiration to carry the ions up the stem, they accumulate in the root xylem and lower the water poten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from the Ancient Greek word (''xylon''), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called ''vessels''. Xylem also contains two other type of cells: parenchyma and fibers. Xylem can be found: * in vascular bundles, present in non-woody plants and non-woody parts of woody plants * in secondary xylem, laid down by a meristem called the vascular cambium in woody plants * as part of a stelar arrangement n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guttation
Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi, which are not plants but were previously categorized as such and studied as part of botany. Guttation (from Latin ''gutta'' drop) is not to be confused with dew, which condenses from the atmosphere onto the plant or fungus surface and does not originate from within them. Guttation generally happens at night. Process At night, transpiration usually does not occur, because most plants have their stomata closed. When there is a high soil moisture level, water will enter plant roots, because the water potential of the roots is lower than in the soil solution. The water will accumulate in the plant, creating a slight root pressure. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes or water glands, forming drops. Root pressure provides the impetus for this flow, rather than transpirational ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplasts
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules Adenosine triphosphate, ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. A chloroplast is characterized by Chloroplast membrane, its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
