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Allelopathy
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see black walnut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ailanthus Altissima
''Ailanthus altissima'' , commonly known as tree of heaven, ailanthus, varnish tree, or in Chinese as ''chouchun'' (), is a deciduous tree in the family Simaroubaceae. It is native to northeast and central China, and Taiwan. Unlike other members of the genus ''Ailanthus'', it is found in temperate climates rather than the tropics. The tree grows rapidly, and is capable of reaching heights of in 25 years. While the species rarely lives more than 50 years, some specimens exceed 100 years of age. Its suckering ability allows this tree to clone itself indefinitely. It is considered a noxious weed and vigorous invasive species, and one of the worst invasive plant species in Europe and North America. In 21st-century North America, the invasiveness of the species has been compounded by its harboring of the also destructive and invasive spotted lanternfly. Description ''A. altissima'' is a medium-sized tree that reaches heights between with a diameter at breast height ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centaurea Stoebe
''Centaurea stoebe'', the spotted knapweed or panicled knapweed, is a species of '' Centaurea'' native to eastern Europe, although it has spread to North America, where it is considered an invasive species. It forms a tumbleweed, helping to increase the species' reach, and the seeds are also enabled by a feathery pappus. Description ''Centaurea stoebe'' is a biennial or short-lived perennial plant, and it usually has a stout taproot and pubescent stems when young. It has pale and deeply-lobed leaves covered in fine short hairs. First-year plants produce a basal rosette, alternate, up to long, deeply divided into lobes. It produces a stem in its second year of growth. Stem leaves are progressively less lobed, getting smaller toward the top. The stem is erect or ascending, slender, hairy and branching, and can grow up to tall. Protruding from black-tipped sepals, the flower blooms from July to September. The flower head is wide, with vibrant pink to lavender (or more rarely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allocasuarina
''Allocasuarina'' is a genus of trees in the flowering plant family Casuarinaceae. They are endemic to Australia, occurring primarily in the south. Like the closely related genus '' Casuarina'', they are commonly called sheoaks or she-oaks. Wilson and Johnson distinguish the two very closely related genera, '' Casuarina'' and ''Allocasuarina'' on the basis of: *'' Casuarina'': the mature samaras being grey or yellow-brown, and dull; cone bracteoles thinly woody, prominent, extending well beyond cone body, with no dorsal protuberance; *''Allocasuarina'': the mature samaras being red-brown to black, and shiny; cone bracteoles thickly woody and convex, mostly extending only slightly beyond cone body, and usually with a separate angular, divided or spiny dorsal protuberance. Description They are trees or shrubs that are notable for their long, segmented branchlets that function as leaves. Formally termed cladodes, these branchlets somewhat resemble pine needles, although sheoa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species Distribution
Species distribution —or species dispersion — is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distribution change depending on the scale at which they are viewed, from the arrangement of individuals within a small family unit, to patterns within a population, or the distribution of the entire species as a whole (range). Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density. Range In biology, the range of a species is the geographical area within which that species can be found. Within that range, distribution is the general structure of the species population, while dispersion is the variation in its population density. Range is often described with the following qualities: * Sometimes a distinction is made bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invasive Plants
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food webfor example the purple sea urchin (''Strongylocentrotus purpuratus'') which has decimated kelp forests along the northern California coast due to overharvesting of its natural predator, the California sea otter (''Enhydra lutris''). Since the 20th century, invasive species have become a serious economic, social, and environmental threat. Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juglans Nigra
''Juglans nigra'', the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. Wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees. Black walnut is an important tree commercially, as the wood is a deep brown color and easily worked. Walnut seeds ( nuts) are cultivated for their distinctive and desirable taste. Walnut trees are grown both for lumber and food, and many cultivars have been developed for improved quality wood or nuts. Black walnut is susceptible to thousand cankers disease, which provoked a decline of walnut trees in some regions. Black walnut is anecdotally known for being allelopathic, which means that it releases chemicals from its roots and other tissues that may harm other or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyperus Rotundus
''Cyperus rotundus'' (coco-grass, Java grass, nut grass, purple nut sedge or purple nutsedge, red nut sedge, Khmer ''kravanh chruk''Martin, Robert & Pol Chanthy, 2009''Weeds of Upland Cambodia'', ACIAR Monagraph 141, Canberra.) is a species of sedge (Cyperaceae) native to Africa, southern and central Europe (north to France and Austria), and southern Asia. The word ''cyperus'' derives from the Greek , ''kyperos'', and ''rotundus'' is from Latin, meaning "round". The earliest attested form of the word ''cyperus'' is the Mycenaean Greek , ''ku-pa-ro'', written in Linear B syllabic script. Description ''Cyperus rotundus'' is a perennial plant, that may reach a height of up to . The names "nut grass" and "nut sedge" – shared with the related species ''Cyperus esculentus'' – are derived from its tubers, that somewhat resemble nuts, although botanically they have nothing to do with nuts. As in other Cyperaceae, the leaves sprout in ranks of three from the base of the plant, aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casuarina Litter
''Casuarina'' is a genus of 17 tree species in the family Casuarinaceae, native to Australia, the Indian subcontinent, southeast Asia, islands of the western Pacific Ocean, and eastern Africa. It was once treated as the sole genus in the family, but has since been split into four genera (see: Casuarinaceae).Flora of Australia''Casuarina''/ref> They are evergreen shrubs and trees growing to tall. The slender, green to grey-green twigs bearing minute scale-leaves in whorls of 5–20. The apetalous flowers are produced in small catkin-like inflorescences. Most species are dioecious, but a few are monoecious. The fruit is a woody, oval structure superficially resembling a conifer cone, made up of numerous carpels, each containing a single seed with a small wing. The generic name is derived from the Malay word for the cassowary, ''kasuari'', alluding to the similarities between the bird's feathers and the plant's foliage, though the tree is called ''ru'' in Modern Malay. Karen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelids, echinoderms and cnidarians. The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata. Invertebrates vary widely in size, from 50 μm (0.002 in) rotifers to the 9–10 m (30–33 ft) colossal squid. Some so-called invertebrates, such as the Tunicata and Cephalochordata, are more closely related to vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy. Etymology The word "invertebrate" comes from the Latin word ''vertebra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals. Etymology The term ''sponge'' derives from the Ancient Greek word ( 'sponge'). Overview Sponges are similar to other animals in that they are multicellula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfalfa
Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as well as a green manure and cover crop. The name alfalfa is used in North America. The name lucerne is the more commonly used name in the United Kingdom, South Africa, Australia, and New Zealand. The plant superficially resembles clover (a cousin in the same family), especially while young, when trifoliate leaves comprising round leaflets predominate. Later in maturity, leaflets are elongated. It has clusters of small purple flowers followed by fruits spiralled in 2 to 3 turns containing 10–20 seeds. Alfalfa is native to warmer temperate climates. It has been cultivated as livestock fodder since at least the era of the ancient Greeks and Romans. Etymology The word ''alfalfa'' is a Spanish modification of the Arabic word ''al-faṣf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
