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Equisetaceae
Equisetaceae, sometimes called the horsetail family, is the only extant family of the order Equisetales, with one surviving genus, ''Equisetum'', which comprises about twenty species. Evolution and systematics Equisetaceae is the only surviving family of the Equisetales, a group with many fossils of large tree-like plants that possessed ribbed stems similar to modern horsetails. ''Pseudobornia'' is the oldest known relative of ''Equisetum''; it grew in the late Devonian, about 375 million years ago and is assigned to its own order. All living horsetails are placed in the genus ''Equisetum''. But there are some fossil species that are not assignable to the modern genus. ''Equisetites'' is a " wastebin taxon" uniting all sorts of large horsetails from the Mesozoic; it is almost certainly paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is sai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fern Families
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except the lycopods, and differ from mosses and other bryophytes by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls, that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns. They produce coiled fiddleheads that uncoil and expand into fronds. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida, comprising both the leptosporangiate (Polypodiidae) and eusporangiate ferns, the latter group including horsetails, whisk ferns, marattioid ferns, and ophioglossoid ferns. Ferns first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equisetum
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass Equisetidae, which for over 100 million years was much more diverse and dominated the understorey of late Paleozoic forests. Some equisetids were large trees reaching to tall. The genus ''Calamites'' of the family Calamitaceae, for example, is abundant in coal deposits from the Carboniferous period. The pattern of spacing of nodes in horsetails, wherein those toward the apex of the shoot are increasingly close together, is said to have inspired John Napier to invent logarithms. Modern horsetails first appeared during the Jurassic period. A superficially similar but entirely unrelated flowering plant genus, mare's tail (''Hippuris''), is occasionally referred to as "horsetail", and adding to confusion, the name "mare's tail" is someti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equisetales
Equisetales is an order of subclass Equisetidae with only one living family, Equisetaceae, containing the genus '' Equisetum'' (horsetails). Classification In the molecular phylogenetic classification of Smith et al. in 2006, Equisetales, in its present circumscription, was held to be the sole member of class Equisetopsida. The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009) which placed all land plants in Equisetopsida, made it the sole member of subclass Equisetidae, equivalent to Smith's Equisetopsida. The placement of Equisetales in subclass Equisetidae has subsequently been followed in the classifications of Christenhusz and Chase (2014) and PPG I (2016). The fossil record includes additional extinct species in Equisetaceae and the extinct families Calamitaceae, Archaeocalamitaceae and Phyllothecaceae The prehistoric family Phyllothecaceae, of the plant order Equisetales, was erected in 1828 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Horsetail
''Equisetum arvense'', the field horsetail or common horsetail, is an herbaceous perennial plant in the Equisetidae (horsetails) sub-class, native throughout the arctic and temperate regions of the Northern Hemisphere. It has separate sterile non-reproductive and fertile spore-bearing stems growing from a perennial underground rhizomatous stem system. The fertile stems are produced in early spring and are non-photosynthetic, while the green sterile stems start to grow after the fertile stems have wilted and persist through the summer until the first autumn frosts.Hyde, H. A., Wade, A. E., & Harrison, S. G. (1978). ''Welsh Ferns''. National Museum of Wales .Flora of North America''Equisetum arvense''/ref> It is sometimes confused with mare's tail, ''Hippuris vulgaris''. Rhizomes can pierce through the soil up to in depth. This allows this species to tolerate many conditions and is hard to get rid of even with the help of herbicides. Taxonomy Linnaeus described field horsetail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudobornia
''Pseudobornia'' is a genus of plants known only from fossils found from the Upper Devonian. It contains a single species ''Pseudobornia ursina'', and is the earliest fossil assigned with certainty to the Equisetopsida. The first fossils of ''Pseudobornia'' were collected by Johan Gunnar Andersson on Bear Island in the 1890s. Hans-Joachim Schweitzer, a paleobotanist, was the first to interpret the fossils as belonging to a large tree, based on additional fossils discovered in Alaska in the 1960s. The probable relationships within Equisetidae Equisetidae is one of the four subclasses of Polypodiopsida (ferns), a group of vascular plants with a fossil record going back to the Devonian. They are commonly known as horsetails. They typically grow in wet areas, with whorls of needle-lik ... are shown in the cladogram below. The position where ''Ibyka'' would be has been added. References Horsetails Late Devonian plants Prehistoric plant genera Late Devonian f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extant Taxon
Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, '' recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members still alive, as opposed to (all) being extinct. For example: * The moose (''Alces alces'') is an extant species, and the dodo (''Raphus cucullatus'') is an extinct species. * In the group of molluscs known as the cephalopods, there were approximately 600 extant species and 7,500 extinct species. A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as extant if there are new discoveries of living species (" Lazarus species"), or if previously-known extant species are reclassified as members of the taxon. Most biologists, zoologists, and botanists are in practice neontologists, and the term neontologist is us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Million Years Ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). Together they make a reference system, one to a quantity, the other to a particular place 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 ''Ma'' (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 such year number "X ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wastebin Taxon
Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by either their designated members' often superficial similarity to each other, or their ''lack'' of one or more distinct character states or by their ''not'' belonging to one or more other taxa. Wastebasket taxa are by definition either paraphyletic or polyphyletic, and are therefore not considered valid taxa under strict cladistic rules of taxonomy. The name of a wastebasket taxon may in some cases be retained as the designation of an evolutionary grade, however. The term was coined in a 1985 essay by Steven Jay Gould. Examples There are many examples of paraphyletic groups, but true "wastebasket" taxa are those that are known not to, and perhaps not intended to, represent natural groups, but are nevertheless used as convenient group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
