The dicotyledons, also known as dicots, are a group of 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, whose seed 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 typically has two embryonic leaves or cotyledons A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants (angiosperms). Species with one cotyledon are called monocotyledonous (or, ". There are around 199,350 species In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or within this group.[1] Flowering plants that are not dicotyledons are monocotyledons Monocotyledons, also known as monocots, are one of two major groups of flowering plants that are traditionally recognized, the other being dicotyledons, or dicots. Monocot seedlings typically have one cotyledon (seed-leaf), in contrast to the two cotyledons typical of dicots. Monocots have been recognized at various taxonomic ranks, and under, typically having one embryonic leaf.
Dicotyledons are not a monophyletic In common cladistic usage, monophyletic describes a group of organisms that form a clade, consisting of a last common ancestor and all of its descendants. The term is not synonymous with the less common term holophyly, which does not include a last common ancestor. It is contrasted with the terms paraphyly, which is a taxonomic group consisting of group, and therefore the names "dicotyledons" and "dicots" are, strictly speaking, deprecated. However, the vast majority of "dicots", do form a monophyletic group called the eudicots Eudicots and Eudicotyledons are terms introduced by Doyle & Hotton to refer to a monophyletic group of flowering plants that had been called tricolpates or non-Magnoliid dicots by previous authors. The term means, literally, "true dicotyledons" as it contains the majority of plants that have been considered dicotyledons and have or tricolpates. These may be distinguished from all other flowering plants by the structure of their 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. Other dicotyledons and monocotyledons have monosulcate pollen, or forms derived from it, whereas eudicots have tricolpate pollen, or derived forms, the pollen having three or more pores set in furrows called colpi.
Traditionally the dicots have been called the Dicotyledones (or Dicotyledoneae), at any rank. If treated as a class, as in the Cronquist system, they may be called the Magnoliopsida after the type genus In biology, a type is that which fixes a name to a taxon. Depending on the nomenclature code which is applied to the organism in question, a type may be a specimen, culture, illustration, description or taxon Magnolia Magnolia is a large genus of about 210 flowering plant species in the subfamily Magnolioideae of the family Magnoliaceae. It is named after French botanist Pierre Magnol. In some schemes, the eudicots are treated as a separate class, the Rosopsida (type genus Rosa), or as several separate classes. The remaining dicots (palaeodicots) may be kept in a single paraphyletic class, called Magnoliopsida, or further divided.
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Compared to Monocotyledons
Aside from cotyledon number, other broad differences have been noted between monocots and dicots, although these have proven to be differences primarily between monocots and eudicots Eudicots and Eudicotyledons are terms introduced by Doyle & Hotton to refer to a monophyletic group of flowering plants that had been called tricolpates or non-Magnoliid dicots by previous authors. The term means, literally, "true dicotyledons" as it contains the majority of plants that have been considered dicotyledons and have. Many early-diverging dicot groups have "monocot" characteristics such as scattered vascular bundles, trimerous flowers, and non-tricolpate pollen. In addition, some monocots have dicot characteristics such as reticulated leaf veins In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. As an evolutionary trait, the flatness of leaves works to expose the chloroplasts to more light and to increase the absorption of carbon dioxide at the expense of water loss. In the Devonian period, when carbon.
Classification
APG (Angiosperm Phylogeny Group) vs. Cronquist Classification
The following lists are of the orders formerly placed in the dicots, giving their new placement in the APG The Angiosperm Phylogeny Group, or APG, refers to two international groups of systematic botanists who came together to try to establish a consensus view of the taxonomy of flowering plants that would reflect new knowledge in angiosperm relationships based upon molecular systematics studies. Three papers resulted from these collaborations,-system and that under the older Cronquist system, which is still in wide use.
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Dicot
hu, 21 Aug 2008 10:35:03 GM
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