Information AboutMonocotyledon |
| CATEGORIES ABOUT MONOCOTYLEDON | |
| botanical nomenclature | |
| plant taxonomy | |
| SHOPPER'S DELIGHT | |
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The Monocotyledons or '''monocots''' are an extremely important group of ). The largest family in this group (and in the flowering plants) is the orchids (usually taken to be the family '' Orchidaceae '', but sometimes treated at the Rank of order), with some twenty thousand species. These have very complex (and striking) flowers, adapted for highly specific Insect Pollination . The economically most important family in this group (and in the flowering plants) are the grasses, family ''Gramineae'' or '' Poaceae ''. These include all the true Grains (rice, wheat, maize, etc), the pasture grasses and the Bamboo s. This family of the true grasses have evolved in another direction, becoming highly specialized for wind pollination. Grasses produce much smaller flowers, which are gathered in highly visible plumes ( Inflorescence s). A further noteworthy, and economically important, family is the palm family, '' Palmae '' or '' Arecaceae ''. 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 Seed s. This as opposed to the traditional Dicotyledon es, which typically have two cotyledons. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character. Nevertheless, monocots are a distinctive group. 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. For example, a monocot's flower could have three, six, or nine petals. Many monocots also have Leaves with parallel veins. with a typical monocot perigone and parallel leaf venation]] MORPHOLOGY, COMPARED TO THE (FORMER) DICOTYLEDONS The schoolbooks list the differences between monocotyledons and Dicotyledons as follows. Obviously this is a broad sketch only, not to be taken literally. There are many exceptions. The differences indicated are more true for Monocots versus Eudicots , as per APG : Flowers: In monocots, flowers are trimerous (number of flower parts in a whorl in threes) while in dicots the flowers are tetramerous or pentamerous (flower parts are in fours or fives). Pollen: In monocots, pollen has one Furrow or Pore while dicots have three. Seeds: In monocots, the embryo has one Cotyledon while the embryo of the dicot has two. Stems: In monocots, Vascular Bundle s in the Stem are scattered, in dicots arranged in a ring. Roots: In monocots, roots are Adventitious , while in dicots they develop from the Radicle . Leaves: In monocots, the major leaf Veins are Parallel , while in dicots they are reticulate. 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 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. TAXONOMY The monocots are considered to form a Monophyletic group arising early in the history of the Flowering Plant s. The earliest fossils presumed to be monocot remains date from the Early Cretaceous period. A taxonomist has 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. 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). REFERENCES AND EXTERNAL LINKS
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