Monocotyledons, also known as monocots, are one of two major groups 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, (or angiosperms) that are traditionally recognized, the other being dicotyledons The dicotyledons, also known as dicots, are a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group. Flowering plants that are not dicotyledons are monocotyledons, typically having one embryonic leaf, or dicots. Monocot seedlings A seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl (embryonic shoot), and the cotyledons (seed leaves). The two classes of flowering plants are distinguished by their numbers typically have one cotyledon 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, " (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-leaf), in contrast to the two cotyledons typical of dicots. Monocots have been recognized at various taxonomic ranks, and under various names (see below). The APG II system The APG II system was published 4½ years after its predecessor, the APG system, which was published in the Annals of the Missouri Botanical Garden in the autumn of 1998. Each of these systems represented the broad consensus of a number of systematic botanists, united in the APG, working at several institutions worldwide recognises a clade A clade[note 1] is a group consisting of an organism and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological classification. In called "monocots" but does not assign it to a taxonomic rank.
There are between 50,000 and 60,000 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; according to IUCN The International Union for Conservation of Nature is an international organization dedicated to natural resource conservation. The stated goal of the organization is to help the world find pragmatic solutions to the most pressing environment and development challenges. The group publishes a "Red List" compiling information from a there are 59,300 species.[1] The largest family in this group (and in the flowering plants as a whole) by number of species are the orchids (family Orchidaceae Orchidaceae, commonly referred to as the Orchid family, is a morphologically diverse and widespread family of monocots. It is currently believed to be the second largest family of flowering plants , with between 21,950 and 26,049 currently accepted species, found in 880 genera. The number of orchid species equals more than twice the number of bird), with more than 20,000 species.[2] In agriculture Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and stratified societies. The study of agriculture is known as the majority of the biomass produced comes from monocots.[3] The true grasses, family Poaceae Poaceae is a family in the Class Liliopsida (the monocots) of the flowering plants. Plants of this family are usually called grasses, or, to distinguish them from other graminoids, true grasses; the shrub- or tree-like plants in this family are called bamboo (there are also herbaceous, non-woody bamboos). There are about 600 genera and some 9,000 (Gramineae), are the most economically important family in this group. These include all the true grains (rice Rice is the seed of the monocot plant Oryza sativa. As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East and South Asia, the Middle East, Latin America, and the West Indies. It is the grain with the second-highest worldwide production, after maize, wheat Wheat is a grass, originally from the Fertile Crescent region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize (784 million tons) and rice (651 million tons). Globally, wheat is the leading source of vegetable protein in human food, having a, maize Maize , known in many English-speaking countries as corn, is a grass domesticated by indigenous peoples in Mesoamerica in prehistoric times. The Aztecs and Mayans cultivated it in numerous varieties throughout central and southern Mexico, to cook or grind in a process called nixtamalization. Later the crop spread through much of the Americas, etc.), the pasture grasses, sugar cane Sugarcane is any of six to thirty-seven species of tall perennial grasses of the genus Saccharum (family Poaceae, tribe Andropogoneae). Native to warm temperate to tropical regions of Asia, they have stout, jointed, fibrous stalks that are rich in sugar, and measure two to six meters (six to nineteen feet) tall. All sugar cane species interbreed,, and the bamboos Bamboo listen is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family. True grasses have evolved to become highly specialised for wind pollination. Grasses produce much smaller flowers, which are gathered in highly visible plumes (inflorescences An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified. The modifications can involve the length and the nature of the internodes and the). Other economically important monocot families are the palm family (Arecaceae Arecaceae or Palmae , the palm family, is a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates. Most palms are distinguished by their large, compound, evergreen leaves), banana family (Musaceae Musaceae is a botanical name for a family of flowering plants. The family is native to the tropics of Africa and Asia. The plants have a large herbaceous growth habit with leaves with overlapping basal sheaths that form a pseudostem making some members appear to be woody trees), ginger family (Zingiberaceae Zingiberaceae, or the Ginger family, is a family of flowering plants consisting of aromatic perennial herbs with creeping horizontal or tuberous rhizomes, comprising ca. 52 genera and more than 1300 species, distributed throughout tropical Africa, Asia, and the Americas) and the onion family Alliaceae Alliaceae is a family of herbaceous perennial flowering plants. They are monocots, part of order Asparagales. The family has been widely but not universally recognized. In the past, the plants involved were often treated as belonging to the family Liliaceae, and still are, in some long-running floristic projects in which obsolete taxonomic systems, which includes such ubiquitously used vegetables as onions Onion is a term used for many plants in the genus Allium. They are known by the common name "onion" but, used without qualifiers, it usually refers to Allium cepa. Allium cepa is also known as the "garden onion" or "bulb" onion. Above ground, the onion shows only a single vertical shoot; the bulb grows underground, and garlic Allium sativum, commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Garlic has been used throughout history for both culinary and medicinal purposes. The garlic plant's bulb is the most commonly used part of the plant. With the exception of the single clove.
Many plants cultivated for their blooms are also from the monocot group, notably lilies The genus Lilium are herbaceous flowering plants growing from bulbs. Most species are native to the temperate northern hemisphere. They comprise a genus of about 110 species in the lily family, daffodils Narcissus is the botanic name for a genus of mainly hardy, mostly spring-flowering, bulbs in the Amaryllis family native to Europe, North Africa, and Asia. There are also several Narcissus species that bloom in the autumn. Though Hortus Third cites 26 wild species, Daffodils for North American Gardens cites between 50 and 100 including species, irises Iris is a genus of 260 species of flowering plants with showy flowers. It takes its name from the Greek word for a rainbow, referring to the wide variety of flower colors found among the many species. As well as being the scientific name, iris is also very widely used as a common name; for one thing, it refers to all Iris species, though some, amaryllis Amaryllis is also known as the belladonna lily or naked ladies. The genus has two species and the more famous of the two, Amaryllis belladonna, is a native of South Africa, particularly the rocky southwest region near the Cape. It should not be confused with Hippeastrum, a flowering bulb commonly sold in the winter months for its ability to bloom, orchids Orchidaceae, commonly referred to as the Orchid family, is a morphologically diverse and widespread family of monocots. It is currently believed to be the second largest family of flowering plants , with between 21,950 and 26,049 currently accepted species, found in 880 genera. The number of orchid species equals more than twice the number of bird, cannas Canna is a genus of nineteen species of flowering plants. The closest living relations to cannas are the other plant families of the order Zingiberales, that is the gingers, bananas, marantas, heliconias, strelitzias, etc, bluebells and tulips A tulip is a bulbous plant in the genus Tulipa, comprising 109 species with showy flowers, in the family Liliaceae. The species native range includes southern Europe, North Africa, and Asia from Anatolia and Iran in the west to northeast of China. The centre of diversity of the genus is in the Pamir and Hindu Kush mountains and the steppes of.
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Name, characters
The name monocotyledons is derived from the traditional botanical name Monocotyledones, which derives from the fact that most members of this group have one cotyledon 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, ", or embryonic leaf, in their 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. By contrast, the traditional dicotyledons The dicotyledons, also known as dicots, are a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group. Flowering plants that are not dicotyledons are monocotyledons, typically having one embryonic leaf typically have two cotyledons. From a diagnostic point of view the number of cotyledons is neither a particularly handy (as they are only present for a very short period in a plant's life), nor totally reliable character.
Nevertheless, monocots are a distinctive group.[4] One of the most noticeable traits is that a monocot's flower is trimerous, with the flower parts in threes or in multiples of three. That is to say, a monocotyledon's flower typically has three, six, or nine petals. Many monocots also have leaves 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 with parallel veins.
Hypoxis decumbens L. Carl Linnaeus [a 2] (Latinized as Carolus Linnaeus [a 3], also known after his ennoblement as Carl von Linné , 23 May[a 1] 1707 – 10 January 1778) was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of with a typical monocot perigone and parallel leaf venationEvolution
Monocots evolved from a single ancestor, and are younger than dicots, from which they probably branched off, as recent genetic research has shown. They evolved 100-120 million years ago, shortly after the flowering plant explosion.
Morphology, compared to the (broadly defined) dicotyledons
The traditionally listed differences between monocotyledons and dicotyledons are as follows. This is a broad sketch only, not invariably applicable, as there are a number of exceptions. The differences indicated are more true for monocots 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 versus 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.[4]
Slice of onion, showing parallel veins in cross section Ceroxylon quindiuense Ceroxylon quindiuense , is a palm native to the Andean high altitude valley of Cocora in the department of Quindío, northwest Colombia (Quindio wax palm) is considered the tallest monocot in the worldA number of these differences are not unique to the monocots. For example, trimerous flowers and monosulcate pollen are also found in magnoliids.[4] Exclusively adventitious roots are found also in Nymphaeaceae Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus Nymphaea contains about 35 species across the Northern and some of the Piperaceae Piperaceae is the botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists: it is sometimes known as the "pepper family". The best known species is Piper nigrum, which yields the most famous peppercorns used as a spice, including "black pepper", although its cousins in the family.[4] Similarly, at least one of these traits, parallel leaf veins, is far from universal among the monocots. Monocots with reticulate leaf veins are found in a wide variety of monocot families: for example, Trillium Trillium is a genus of about 40–50 species of spring ephemeral perennials, native to temperate regions of North America and Asia, Smilax Smilax is a genus of about 300-350 species, found in temperate zones, tropics and subtropics worldwide. In China for example about 80 are found , while there are 20 in North America north of Mexico. They are climbing flowering plants, many of which are woody and/or thorny, in the monocotyledon family Smilacaceae, native throughout the tropical and (greenbriar), and Pogonia (an orchid), and the Dioscoreales.[4] Nevertheless, this list of traits is a generally valid set of contrasts, especially when contrasting monocots with eudicots rather than non-monocot flowering plants in general.[4]
Emergence
Main article: Cotyledon#Epigeal versus hypogeal developmentSome monocots, such as grasses, have hypogeal emergence, where the mesocotyl elongates and pushes the coleoptile (which encloses and protects the shoot tip) toward the soil surface.[5] Since elongation occurs above the cotyledon, it is left in place in the soil where it was planted. Many dicots have epigeal emergence, the hypocotyl elongates and becomes arched in the soil. As the hypocotyl continues to elongate, it pulls the cotyledons upward, above the soil surface.
Vascular system
Stems of two Roystonea regia palms showing anomalous secondary growth in monocots. Note the characteristic fibrous roots, typical of monocots.Monocots have a distinctive arrangement of vascular tissue known as an atactostele in which the vascular tissue is scattered rather than arranged in concentric rings. Many monocots are herbaceous and do not have the ability to increase the width of a stem (secondary growth) via the same kind of vascular cambium found in non-monocot woody plants.[4] However, some monocots do have secondary growth, and because it does not arise from a single vascular cambium producing xylem inwards and phloem outwards, it is termed "anomalous secondary growth".[6] Examples of large monocots which either exhibit secondary growth, or can reach large sizes without it, are palms (Arecaceae), screwpines (Pandanaceae), bananas (Musaceae), Yucca, Aloe, Dracaena, and Cordyline.[4]
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PHOEBE
ue, 17 Nov 2009 11:11:00 GM
Which of the following structures is found in a . monocot. ? A. Two embryonic leaves B. Fibrous roots C. Vascular bundles in a ring D. Flower parts in groups of four or five E. Network of veins in leaves Which of the following structures is ...
