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Flower July 2011-2 1 Cropped
Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants (angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, modified leaves; corolla, the petals; androecium, the male reproductive unit consisting of stamens and pollen; and gynoecium, the female part, containing style and stigma, which receives the pollen at the tip of the style, and ovary, which contains the ovules. When flowers are arranged in groups, they are known collectively as inflorescences. Floral growth originates at stem tips and is controlled by MADS-box genes. In most plant species flowers are heterosporous, and so can produce sex cells of both sexes. Pollination mediates the transport of pollen to the ovules in the ovaries, to facilitate sexual reproduction. It can occur between different plants, as in cross-pollination, or between flowers on the same plant or even the same flower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnolia Grandiflora
''Magnolia grandiflora'', commonly known as the southern magnolia or bull bay, is a tree of the family Magnoliaceae native to the Southeastern United States, from Virginia to central Florida, and west to East Texas. Reaching in height, it is a large, striking evergreen tree, with large, dark-green leaves up to long and wide, and large, white, fragrant flowers up to in diameter. Although endemic to the evergreen lowland subtropical forests on the Gulf and South Atlantic coastal plain, ''M. grandiflora'' is widely cultivated in warmer areas around the world. The timber is hard and heavy, and has been used commercially to make furniture, pallets, and veneer. Description ''Magnolia grandiflora'' is a medium to large evergreen tree which may grow tall.Gardiner, p. 144 It typically has a single stem (or trunk) and a Pyramid (geometry), pyramidal shape. The leaf, leaves are simple and broadly ovate, long and broad, with smooth margins. They are dark green, stiff, and leathery, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterospory
Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory independently in several plant groups: the Lycopodiopsida, clubmosses, the ferns including the Equisetopsida, arborescent horsetails, and progymnosperms. This occurred as part of the process of evolution of the timing of Sexual differentiation, sex differentiation.Sussex, I.M. (1966) The origin and development of heterospory in vascular plants. Chapter 9 in ''Trends in Plant morphogenesis'', ed. by E.G. Cutter, Longmans. Four extant groups of plants are heterosporous; Selaginella, Isoetes, Salviniales and seed plants. Origin of heterospory Heterospory evolved due to natural selection that favoured an increase in propagule size compared with the smaller spores of homosporous plants. Heterosporous plants, similar to anisosporic plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. The Jurassic constitutes the second and middle period of the Mesozoic, Mesozoic Era as well as the eighth period of the Phanerozoic, Phanerozoic Eon and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province (CAMP). The beginning of the Toarcian Age started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of Anoxic event, oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Million Years Ago
Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used with Mya or Ma. Together they make a reference system, one to a quantity, the other to a particular point in a year numbering system that is ''time before the present''. Myr is deprecated in geology, but in astronomy ''Myr'' is standard. Where "myr" ''is'' seen in geology, it is usually "Myr" (a unit of mega-years). In astronomy, it is usually "Myr" (Million years). Debate In geology, a debate remains open concerning the use of ''Myr'' (duration) plus ''Mya'' (million years ago) versus using only the term ''Ma''. In either case, the term '' Ma'' is used in geology literature conforming to ISO 31-1 (now ISO 80000-3) and NIST 811 recommended practices. Traditional style geology literature is written: The "ago" is implied, so that any s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fruit
In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propagated using the movements of humans and other animals in a symbiotic relationship that is the means for seed dispersal for the one group and nutrition for the other; humans, and many other animals, have become dependent on fruits as a source of food. Consequently, fruits account for a substantial fraction of the world's agricultural output, and some (such as the apple and the pomegranate) have acquired extensive cultural and symbolic meanings. In common language and culinary usage, ''fruit'' normally means the seed-associated fleshy structures (or produce) of plants that typically are sweet (or sour) and edible in the raw state, such as apples, bananas, grapes, lemons, oranges, and strawberries. In botanical usage, the term ''fruit'' als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds are the product of the ripened ovule, after the embryo sac is fertilization, fertilized by Pollen, sperm from pollen, forming a zygote. The embryo within a seed develops from the zygote and grows within the mother plant to a certain size before growth is halted. The formation of the seed is the defining part of the process of reproduction in seed plants (spermatophytes). Other plants such as ferns, mosses and marchantiophyta, liverworts, do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological Ecological niche, niches on land, from forests to grasslands both in hot and cold climates. In the flowering plants, the ovary ripens into a fruit which contains the seed and serves to disseminate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most important of these proteins are the histones. Aided by chaperone proteins, the histones bind to and condense the DNA molecule to maintain its integrity. These eukaryotic chromosomes display a complex three-dimensional structure that has a significant role in transcriptional regulation. Normally, chromosomes are visible under a light microscope only during the metaphase of cell division, where all chromosomes are aligned in the center of the cell in their condensed form. Before this stage occurs, each chromosome is duplicated ( S phase), and the two copies are joined by a centromere—resulting in either an X-shaped structure if the centromere is located equatorially, or a two-armed structure if the centromere is located distally; the jo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygote
A zygote (; , ) is a eukaryote, eukaryotic cell (biology), cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. The sexual fusion of haploid cells is called karyogamy, the result of which is the formation of a Ploidy#Haploid and monoploid, diploid cell called the zygote or zygospore. History German zoologists Oscar Hertwig, Oscar and Richard Hertwig made some of the first discoveries on animal zygote formation in the late 19th century. In multicellular organisms The zygote is the earliest developmental stage. In humans and most other Anisogamy, anisogamous organisms, a zygote is formed when an egg cell and sperm, sperm cell come together to create a new unique organism. The formation of a cell potency, totipotent zygote with the potential to produce a whole organism depends on epigenetics, epigenetic reprogramming. DNA demethyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilisation
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or offspring. While processes such as insemination or pollination, which happen before the fusion of gametes, are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms, the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. History In antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode called by him as epigenetic. In 1784, Spallanzani established the need of in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectar Guide
Nectar guides are markings or patterns seen in flowers of some angiosperm species, that guide pollinators to their Pollination syndrome, rewards. These markings may appear as lines, spots, or "blotches". Such patterns are also known as "pollen guides" and "honey guides", though some authorities argue for the abandonment of such terms in favour of ''floral guides'' (see, for example, Dinkel & Lunau). Pollination Nectar guides serve as an Signalling theory, interspecific signal that the flower contains a reward. Rewards commonly take the form of nectar (plant), nectar, pollen, or both; however, plants may also produce oil, resins, Floral scent, scents, or waxes. Pollinator visitation can select for various floral traits, including nectar guides, through a process called pollinator-mediated selection. For example, nectar guides are thought to increase pollinator foraging efficiency by reducing handling time. These guides may also decrease nectar robbing, which leads more pollen to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectar
Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal Mutualism (biology), mutualists, which in turn provide plant defense against herbivory#Indirect defenses, herbivore protection. Common nectar-consuming pollinators include mosquitoes, hoverfly, hoverflies, wasps, bees, butterfly, butterflies and moths, hummingbirds, honeyeaters and Bat#Fruit and nectar, bats. Nectar is an economically important substance as it is the sugar source for honey. It is also useful in agriculture and horticulture because the adult stages of some predatory insects feed on nectar. For example, a number of predacious or Parasitoid wasp, parasitoid wasps (e.g., the social wasp species ''Apoica flavissima'') rely on nectar as a primary food source. In turn, these wasps then hunt agricultural pest insects as food ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-pollination
Self-pollination is a form of pollination in which pollen arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms) of the same plant. The term cross-pollination is used for the opposite case, where pollen from one plant moves to a different plant. There are two types of self-pollination: in autogamy, pollen is transferred to the stigma of the same flower; in geitonogamy, pollen is transferred from the anther of one flower to the stigma of another flower on the same flowering plant, or from microsporangium to ovule within a single ( monoecious) gymnosperm. Some plants have mechanisms that ensure autogamy, such as flowers that do not open ( cleistogamy), or stamens that move to come into contact with the stigma. The term selfing that is often used as a synonym is not limited to self-pollination, but also applies to other types of self-fertilization. Occurrence Few plants self-pollinate without the aid of pollen vectors (such as wind or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
