The plant Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004, division In biology, a phylum [note 1] is a taxonomic rank below Kingdom and above Class. "Phylum" is equivalent to the botanical term division Gnetophyta or gnetophytes consists of three genera In biology, a genus is a low-level taxonomic rank (a taxon) used in the classification of living and fossil organisms, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender", cognate with Greek: γένος – genos, "race, stock, kin" of woody plants A woody plant is a plant that uses wood as its structural tissue. They are typically perennial plants that have their stems and larger roots reinforced with wood produced adjacent to the vascular tissues: typically the main stem and larger branches and roots are covered by a layer of thickened bark. Woody plants are usually either trees, shrubs, grouped in the gymnosperms Once an authoritative and major classification level in the plant kingdom, the gymnosperms form today a rather heterogeneous group of seed-bearing plants that includes conifers, cycads, Ginkgo and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos , meaning "naked seeds", after the unenclosed condition of. The living Gnetophyta are in the genera Gnetum Gnetum is a genus of about 30-35 species of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect pollinated as they occur in (family What does and does not belong to each family is determined by a taxonomist. Similarly for the question if a particular family should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing a family Gnetaceae), Welwitschia Welwitschia is a monotypic genus of gymnosperm plant, composed solely of the very distinct Welwitschia mirabilis. It is the only genus of the family Welwitschiaceae, in the order Welwitschiales, in the division Gnetophyta. The plant, which is considered a living fossil, is named after the Austrian botanist Friedrich Welwitsch who discovered it in 1 (family Welwitschiaceae), and Ephedra Ephedra is a genus of gymnosperm shrubs, the only genus in the family Ephedraceae and order Ephedrales. These plants occur in dry climates over a wide area mainly in the northern hemisphere, across southern Europe, north Africa, southwest and central Asia, southwestern North America, and, in the southern hemisphere, in South America south to (family Ephedraceae).
The gnetophytes differ from other gymnosperms (conifers The conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being trees with just a few being shrubs. Typical, cycads Cycads are seed plants characterized by a large crown of compound leaves and a stout trunk. They are evergreen, dioecious plants having large pinnately compound leaves. They are frequently confused with and mistaken for palms or ferns, but are only distantly related to both, and instead belong to the division Cycadophyta, and ginkgos Ginkgo is a genus of highly unusual non-flowering plants with one extant species, G. biloba, which is regarded as a living fossil) in having vessel elements A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers as in the flowering plants The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Together with gymnosperms, they are the only extant groups of seed-producing plants, but they can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers,. In some classifications, all three genera are placed in a single order The Latin suffix -formes meaning "having the form of" is used for the scientific name of orders of birds and fishes, but not for those of mammals and invertebrates (Gnetales) but in others distributed among three orders, each containing a single family and genus. Most morphological and molecular studies confirm that Gnetum and Welwitschia diverged from each other more recently than from Ephedra.[1][2][3][4]
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Ecology and Morphology
The three genera of the gnetophytes are highly specialized to their respective environments, making it difficult to identify homologous characters.[5] The three extant Extant is a term commonly used in biology to refer to taxa that are still in existence (living). The term extant contrasts with extinct. For example, Brandt's Cormorant is an extant species, while the Spectacled Cormorant is an extinct species. Likewise, of the group of molluscs known as the cephalopods, there are approximately 600 extant species genera of gnetophytes, a “bizarre and enigmatic” trio[2], are likely aberrant members of the group, which was diverse and dominant in the Tertiary The Tertiary is a term for a geologic period 65 million to 1.8 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Tertiary extinction event, at the start of the Cenozoic era, spanning to the beginning of.[5] Some synapomorphies of the gnetophytes include enveloping bracts In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves, for example being smaller, larger, or of a different color or texture around the ovules Ovule literally means "small egg." In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integuments forming its outer layer, the nucellus , and the megaspore-derived female gametophyte (or megagametophyte) in its center. The megagametophyte (also called and microsporangia, and a micropylar projection of the outer membrane of the ovule that produces a pollination Pollination is the process by which pollen is transferred in plants, thereby enabling fertilization and sexual reproduction. Pollen grains, which contain the male gametes to where the female gamete(s) are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself. The receptive part of the carpel is called a droplet.[6]
Gnetum Gnetum is a genus of about 30-35 species of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect pollinated as they occur in species are mostly woody Wood is a hard, fibrous tissue found in many plants. It has been used for centuries for both fuel and as a construction material for several types of living areas such as houses. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression. In the strict sense wood is produced as climbers A vine in the broad sense refers to any climbing or trailing plant. The narrower and original meaning is the grapevine (Vitis) in tropical forests. However, the most well-known member of this group, Gnetum gnemon Gnetum gnemon is a species of Gnetum native to southeast Asia and the western Pacific Ocean islands, from Assam south and east through Indonesia and Malaysia to the Philippines and Fiji. Common names include melinjo or belinjo , bago (Malay language, Tagalog language), peesae (Thai language), dae (Kwara'ae language) and bét, rau bép, rau danh or, is a tree. Its seeds are used to produce a crispy krupuk Krupuk, kerupuk, or kroepoek in Indonesia; keropok in Malaysia; kropek in the Philippines; bánh phồng tôm in Vietnam; is a popular snack in parts of East and Southeast Asia. Krupuk are deep fried crackers made from starch and other ingredients that usually give the taste. Prawn based krupuk are popular types of krupuk. They are called krupuk snack known as emping or krupuk belinjo.
Welwitschia Welwitschia is a monotypic genus of gymnosperm plant, composed solely of the very distinct Welwitschia mirabilis. It is the only genus of the family Welwitschiaceae, in the order Welwitschiales, in the division Gnetophyta. The plant, which is considered a living fossil, is named after the Austrian botanist Friedrich Welwitsch who discovered it in 1 comprises only one species, Welwitschia mirabilis. It grows only in the deserts of Namibia Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March 1990 following the Namibian War of Independence. Its and Angola Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city. The exclave province of Cabinda has a border with the Republic of the Congo and the. This strange species has only two large strap-like leaves that grow continuously from the base throughout the plant's life.
Plants of the genus Ephedra Ephedra is a genus of gymnosperm shrubs, the only genus in the family Ephedraceae and order Ephedrales. These plants occur in dry climates over a wide area mainly in the northern hemisphere, across southern Europe, north Africa, southwest and central Asia, southwestern North America, and, in the southern hemisphere, in South America south to are known as jointfirs because they have long slender branches which bear tiny scale-like leaves at their nodes. Ephedra has been traditionally used as a stimulant Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others. Due to their effects typically having an "up" quality to them, stimulants are also occasionally referred to as &, but is a controlled substance A controlled substance is generally a drug or chemical whose manufacture, possession, and use are regulated by a government. This may include illegal drugs and prescription medications today in many jurisdictions because of the risk of harmful or even fatal overdosing The term drug overdose describes the ingestion or application of a drug or other substance in quantities that are excessive. An overdose is widely considered harmful and dangerous as it can result in death.
Knowledge of fossils of the gnetophytes has increased greatly since the 1980s.[1] There are fossils from the Permian The Permian[note 1] is a geologic period and system characterized among land vertebrates by the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs. The Permian Period follows the Carboniferous and extends from 299.0 ± 0.8 to 251.0 ± 0.4 Ma . It is the last period of the Paleozoic,[7] the Triassic The Triassic is a geologic period that extended from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events. The extinction event that closed the Triassic Period has recently been more accurately, and the Jurassic The Jurassic is a geologic period and system that extends from about 199.6± 0.6 Ma to 145.5± 4 Ma, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the "Age of Reptiles". The start of the period is marked by the major Triassic– which may belong to the gnetophytes, but this is uncertain.[8] The fossil record is richer starting in the early Cretaceous The Cretaceous , Latin for "chalky", usually abbreviated K for its German translation Kreide (chalk), is a geologic period and system from circa 145.5 ± 4 to 65.5 ± 0.3 million years (Ma) ago. In the geologic timescale, the Cretaceous follows on the Jurassic Period and is followed by the Paleogene Period of the Cenozoic Era. It is the, with fossils of plants as well as seeds A seed ( /ˈsiːd/ ) is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant. The formation of the seed completes the process of reproduction in seed and pollen Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the female cone of coniferous plants. When pollen lands which can be clearly assigned to the gnetophytes.[8]
Classification
The evolutionary relationships among the seed plants The spermatophytes (also known as phanerogams) comprise those plants that produce seeds. They are a subset of the embryophytes or land plants. The living spermatophytes form five groups: are highly unresolved, and the gnetophytes have played an important role in the formation of phylogenetic In biology, phylogenetics is the study of evolutionary relatedness among various groups of organisms , which is discovered through molecular sequencing data and morphological data matrices. The term phylogenetics is of Greek origin from the terms phyle/phylon (φυλή/φῦλον), meaning "tribe, race," and genetikos (γενετικός hypotheses. Molecular phylogenies of extant gymnosperms have conflicted with morphological characters with regard to whether the gymnosperms as a whole (including gnetophytes) comprise a monophyletic group In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it consists of an ancestor and all its descendants. The term is synonymous with the uncommon term holophyly. It is contrasted with the terms paraphyly, which is a taxon consisting of an ancestor and some of its descendants, and polyphyly, which is a taxon or a paraphyletic A group of taxa is said to be paraphyletic if the group contains its last common ancestor but does not contain all the descendants of that ancestor. This term is used in both phylogenetics[note 1] and linguistics one that gave rise to angiosperms. At issue is whether the Gnetophyta are the sister group Cladistics is a form of biological systematics that classifies species of organisms into hierarchical monophyletic groups. It can be distinguished from other taxonomic systems, such as phenetics, by its focus on shared derived characters (synapomorphies). Previous systems usually employed overall morphological similarity to group species into of angiosperms The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Together with gymnosperms, they are the only extant groups of seed-producing plants, but they can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers,, or whether they are sister to, or nested within, other extant gymnosperms. Numerous fossil gymnosperm clades once existed that are morphologically at least as distinctive as the four living gymnosperm Once an authoritative and major classification level in the plant kingdom, the gymnosperms form today a rather heterogeneous group of seed-bearing plants that includes conifers, cycads, Ginkgo and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos , meaning "naked seeds", after the unenclosed condition of groups, such as Bennettitales Bennettitales is an extinct order of seed plants that first appeared in the Triassic period and became extinct toward the end of the Cretaceous. Some were characterized by thick trunks and pinnately compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement, Caytonia and the glossopterids. When these gymnosperm fossils are considered, the question of gnetophyte relationships to other seed plants becomes even more complicated. Several hypotheses, illustrated below, have been presented to explain seed plant evolution.
Anthophyte hypothesis
From the early twentieth century, the anthophyte hypothesis was the prevailing explanation for seed plant The spermatophytes (also known as phanerogams) comprise those plants that produce seeds. They are a subset of the embryophytes or land plants. The living spermatophytes form five groups: evolution, based on shared morphological In biology "morphology" is the study of the form, structure and configuration of an organism. This includes aspects of the outward appearance [citation needed] as well as the form and structure of the internal parts like bones and organs. This is in contrast to physiology, which deals primarily with function characters between the gnetophytes and angiosperms The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Together with gymnosperms, they are the only extant groups of seed-producing plants, but they can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers,. In this hypothesis, the gnetophytes, along with the extinct order Bennettitales Bennettitales is an extinct order of seed plants that first appeared in the Triassic period and became extinct toward the end of the Cretaceous. Some were characterized by thick trunks and pinnately compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement, are sister to the angiosperms, forming the “anthophytes”.[6] Some morphological characters that were suggested to unite the anthophytes include vessels in wood, net-veined leaves (in Gnetum only), lignin chemistry, the layering of cells in the apical meristem, pollen and megaspore features (including thin megaspore wall), short cambial initials, and lignin syringal groups.[6][9][10][11] However, most genetic studies have rejected the anthophyte hypothesis.[2][12][13][14][15][16][17][18][19][20] Several of these studies have suggested that the gnetophytes and angiosperms have independently derived characters, including flower-like reproductive structures and tracheid vessel elements, that appear shared but are actually the result of parallel evolution.[2][13][6]
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Gnetifer hypothesis
In the gnetifer hypothesis, the gnetophytes are sister to the conifers, and the gymnosperms are a monophyletic group, sister to the angiosperms. The gnetifer hypothesis first formally emerged in the mid-twentieth century, when vessel elements in the gnetophytes were interpreted as being derived from tracheids with circular bordered pits, as in conifers.[6] It did not gain strong support, however, until the emergence of molecular data in the late 1990s.[12][18][21][22] Although the morphological evidence still largely supports the anthophyte hypothesis, there are some morphological commonalities between the gnetophytes and conifers that lend support to the gnetifer hypothesis. These shared traits include: tracheids with scalariform pits with tori interspersed with annular thickenings, absence of scalariform pitting in primary xylem, scale-like and strap-shaped leaves of Ephedra and Welwitschia; and reduced sporophylls.[20][17][23]
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e-ciencia.com, Spain
Este es el caso de una Gimnosperma del Phylum Gnetophyta y en concreto del orden de las Welwitchiales. Dentro de este orden tenemos la familia Welwitchia representada por una sola especie Welwitchia mirabilis. Esta planta vive en el desierto de Namibia ...
StickySpade
Wed, 20 Oct 2004 11:28:00 GM
Any member of the division . Gnetophyta. , a small group of vascular gymnospermous plants that are represented by three genera: Ephedra, Gnetum, and Welwitschia. There are about 35 species in the genus Ephedra, 30 or more in Gnetum, ...
Q. any of the following: -Pinophyta -Cycadophyta -Gnetophyta -Anthophyta without a bunch of big, scientific words please? lol :] i am in sixth grade ;] thanks so much! ok, if you're just going to make fun of me, then dont answer. thanks for wasting your and my time
Asked by ...... - Thu Dec 20 13:27:22 2007 - - 6 Answers - 0 Comments
A. OK, they all end in the letter a nothing over 6 letters in my answer. they also all end in phyta could they be connected... That's 9 letters, sorry all types of plants oh,oh there's an encyclopedia (big book) coming up 2 behind me and look, he's given you loads of information that you don't need,
Answered by Trev - Thu Dec 20 13:30:01 2007
