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Monocotyledons
Hemerocallis flower, with three flower parts in each whorl
Hemerocallis flower, with three flower parts in each whorl
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Monocotyledones
Orders

About 10; see text
Wheat, an economically important monocot
Wheat, an economically important monocot

Monocotyledons or monocots are one of two major groups of flowering plants (angiosperms) that are traditionally recognised, dicotyledons or dicots being the other. Daylilies comprise the small Genus Hemerocallis of flowering plants in the family Hemerocallidaceae. Plants are living Organisms belonging to the kingdom Plantae. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group Wheat ( Triticum spp is a worldwide cultivated grass from the Levant area of the Middle East. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group Dicotyledons, or "dicots", is a name for a group of Flowering plants whose Seed typically has two embryonic leaves or Cotyledons There Monocots have been recognised at various taxonomic ranks, and under various names (see below). The APG II system recognises a clade called "monocots" but does not assign it to a taxonomic rank. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor

Monocots comprise the majority of agricultural plants in terms of biomass produced. There are between 50,000 and 60,000 species within this group; according to IUCN there are 59,300 species. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. [1] The largest family in this group (and in the flowering plants as a whole) by number of species are the orchids (family Orchidaceae), with about twenty thousand species. The economically most important family in this group (and in the flowering plants) are the grasses, family Poaceae (Gramineae). Poaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. Poaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. These include all the true grains (rice, wheat, maize, etc. Grains make up the structure of Metals Metal surfaces contain a number of small crystals known as grains with boundaries where they join Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many Wheat ( Triticum spp is a worldwide cultivated grass from the Levant area of the Middle East. Maize (ˈmeɪz ( Zea mays L. ssp mays) known as corn in some countries is a cereal grain domesticated in Mesoamerica ), the pasture grasses and the bamboos. Bamboo is a group of Woody perennial Evergreen Plants in the True grass family Poaceae, subfamily This family of the true grasses have evolved in another direction, becoming 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 Other economically important monocot families are the palm family (Arecaceae), banana family (Musaceae), ginger family (Zingiberaceae) and the onion family Alliaceae, which includes such ubiquitously used vegetables as onions and garlic. Arecaceae or Palmae (also known by the name Palmaceae, which is taxonomically invalid or commonly palm tree) the palm family is a family of Flowering Musaceae is a Botanical name for a family of Flowering plants. Zingiberaceae, or the Ginger family, is a family of flowering plants consisting of aromatic perennial Herbs with creeping horizontal or tuberous Alliaceae is a family of herbaceous perennial Flowering plants. Organicsalsajpg||thumb|right|Onions used in salsa.]]Cooked onions in frying pan Allium sativum L, commonly known as garlic, is a species in the Onion family Alliaceae.

Many plants cultivated for their blooms are also from the monocot group, notably lilies, daffodils, irises, amaryllis, orchids, cannas, bluebells and tulips. Amaryllis is a monotypic (only one species Genus of plant also known as the Belladonna Lily or naked ladies. Canna (or Canna lily, although not a true Lily) is a Genus of approximately twenty Species of Flowering plants The Common Bluebell ( Hyacinthoides non-scripta, syn Endymion non-scriptus, Scilla non-scripta) is a spring -flowering Bulbous Tulipa, commonly called tulip, is a Genus of about 150 species of bulbous Flowering plants in the family Liliaceae.

Contents

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, or embryonic leaf, in their seeds. A cotyledon ("seed leaf" from Greek: κοτυληδών kotylēdōn, from κοτύλη ''kotýlē'', "cup bowl" A seed (in some plants referred to as a kernel) is a small embryonic Plant enclosed in a covering called the seed coat usually with some stored This as opposed to the traditional Dicotyledones, which typically have two cotyledons. Dicotyledons, or "dicots", is a name for a group of Flowering plants whose Seed typically has two embryonic leaves or Cotyledons There 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. [1] 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 with parallel veins. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis.

Hypoxis decumbens L. with a typical monocot perigone and parallel leaf venation
Hypoxis decumbens L. with a typical monocot perigone and parallel leaf venation

Morphology, compared to the (former) dicotyledons

The traditionally listed differences between monocotyledons and dicotyledons are as follows. Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for This is a broad sketch only, not invariably applicable, as there are a number of exceptions. The differences indicated are more true for monocots versus eudicots, as per the APG II system:

Flowers: In monocots, flowers are trimerous (having three flower parts in a whorl) while in dicots the flowers are tetramerous or pentamerous (flower parts are in fours or fives). Monocotyledons or monocots are one of two major groups of Flowering plants (angiosperms that are traditionally recognised the other being Dicotyledons Eudicots and Eudicotyledons are terms introduced by Doyle & Hotton (1991 to refer to a group of Flowering plants that had been called "tricolpates" or "non-Magnoliid

Pollen: In monocots, pollen has one furrow or pore while dicots have three. The plough ( American spelling plow; both plaʊ is a Tool used in Farming for initial cultivation of soil in preparation for sowing seed Pollen is a fine to coarse powder consisting of microgametophytes ( pollen grains) which produce the male Gametes (sperm cells of

Seeds: In monocots, the embryo has one cotyledon or seed leaf while the embryo of the dicot has two. A cotyledon ("seed leaf" from Greek: κοτυληδών kotylēdōn, from κοτύλη ''kotýlē'', "cup bowl"

Stems: In monocots, vascular bundles in the stem are scattered, in dicots it is arranged in concentric circles or rings. A vascular bundle is a part of the transport system in Vascular plants The transport itself happens in Vascular tissue, which exists in two forms Xylem A stem is one of two main structural axes of a Vascular plant.

Roots: In monocots, roots are adventitious, while in dicots they develop from the radicle. In Botany, the radicle is the first part of a Seedling (a growing plant Embryo) to emerge from the Seed during the process of

Slice of onion, showing parallel veins in cross section
Slice of onion, showing parallel veins in cross section

Leaves: In monocots, the major leaf veins are parallel, while in dicots they are reticulate. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis.

However, these differences are not hard and fast: some monocots have characteristics more typical of dicots, and vice-versa. This is in part because "dicots" are a paraphyletic group with respect to monocots, and some dicots may be more closely related to monocots than to other dicots. In Phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor but does not contain all In particular, several early-branching lineages of "dicots" share "monocot" characteristics, suggesting that these are not defining characters of monocots. When monocots are compared to eudicots, the differences are more concrete. Eudicots and Eudicotyledons are terms introduced by Doyle & Hotton (1991 to refer to a group of Flowering plants that had been called "tricolpates" or "non-Magnoliid

Taxonomy

The monocots are considered to form a monophyletic group arising early in the history of the flowering plants. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group The earliest fossils presumed to be monocot remains date from the early Cretaceous period. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of

Taxonomists have considerable latitude in naming this group, as the monocots are a group above the rank of family. Article 16 of the ICBN allows either a descriptive name or a name formed from the name of an included family. The International Code of Botanical Nomenclature ( ICBN) is the set of rules and recommendations dealing with the formal Botanical names that are given to Descriptive botanical names: Article 16 of the ICBN rules that a name above the rank of family may be either descriptive or formed from the name

Grass sprouting on left (a monocot), showing a single cotyledon. Compared to a dicot (right)
Grass sprouting on left (a monocot), showing a single cotyledon. Compared to a dicot (right)
Image:Ceroxylon quindiuense.jpg
Ceroxylon quindiuense (Quindio wax palm) is the tallest monocot in the world

Historically, the monocotyledons were named:

Each of the systems mentioned above use their own internal taxonomy for the group. The monocotyledons are famous as a group that is extremely stable in its outer borders (it is a well-defined, coherent group), while in its internal taxonomy is extremely unstable (historically no two authoritative systems have agreed with each other on how the monocotyledons are related to each other).

Recent molecular studies have both confirmed the monophyly of the monocots and helped elucidate relationships within this group. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor The APG II system does not assign the monocots to a taxonomic rank, instead recognizing a monocots clade. This system recognizes ten orders of monocots and two families of monocots not yet assigned to any order:

The family Hydatellaceae, assigned to order Poales in the APG II system, has since been recognized as being misplaced in the monocots, and instead proves to be most closely related to the water lilies, family Nymphaeaceae. Petrosaviaceae is the Botanical name of a family of Flowering plants. Acorus is a Genus of Monocot Flowering plants This genus was once placed within the family Araceae (aroids but more recent Alismatales is an order of Flowering plants The order will of necessity contain the family Alismataceae. Asparagales is an order of Flowering plants The order must include the family Asparagaceae, but other families included in the order have varied markedly Dioscoreales is a Botanical name for an order of Flowering plants. Liliales is an order of Monocotyledonous Flowering plants This order of necessity includes the family Liliaceae, but both the family and the order have Pandanales is an order of Flowering plants with a pantropical distribution In Plant taxonomy, the name commelinids (plural not capitalised is used by the APG II system for a Clade within the Monocots, which in its Dasypogonaceae is a Botanical name of a family of Flowering plants. Arecales is an order of Flowering plants The order has been widely recognised only for the past few decades until then the accepted name for the order including Commelinales is the Botanical name of an order of Flowering plants It's considered that the Commelinales together with Zingiberales evolved in the Poales is an order of Flowering plants in the Monocotyledons and includes families of plants such as the grasses, Bromeliads, Zingiberales is an order of Flowering plants. The order has been widely recognised by the taxonomists at least for the past few decades Hydatellaceae is the Botanical name for a family of Flowering plants containing the genus Trithuria, which has been recently re-classified to 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

References and external links

  1. ^ Mark W. Chase (2004). "Monocot relationships: an overview". American Journal of Botany 91: 1645–1655.  

Dictionary

monocotyledon

-noun

  1. any plant belonging to the Monocotyledones (also written Monocotyledonae) or Liliopsida, a class in the Angiospermae, the flowering plants. This group include the grasses, lilies, orchids and palms.
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