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==Name, characters==
==Name, characters==
this is good stuff. 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.
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 (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.<ref>{{cite journal | title=Monocot relationships: an overview | url=http://www.amjbot.org/cgi/content/full/91/10/1645 | journal=American Journal of Botany | year=2004 | volume=91 | pages=1645-1655 | author=Mark W. Chase }}</ref> 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 monocotyledon's flower typically has three, six, or nine petals. Many monocots also have [[leaf|leaves]] with parallel veins.
Nevertheless, monocots are a distinctive group.<ref>{{cite journal | title=Monocot relationships: an overview | url=http://www.amjbot.org/cgi/content/full/91/10/1645 | journal=American Journal of Botany | year=2004 | volume=91 | pages=1645-1655 | author=Mark W. Chase }}</ref> 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 monocotyledon's flower typically has three, six, or nine petals. Many monocots also have [[leaf|leaves]] with parallel veins.
==Taxonomy==
==Taxonomy==
monocotyledons are related to each other).
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 [[Cretaceous|early Cretaceous]] period.
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 botanical names|descriptive name]] or a name formed from the name of an included family.
[[Image:Monocot_vs_dicot_crop_Pengo.jpg|thumb|Grass sprouting on left (a monocot), showing a single cotyledon. Compared to a dicot (right)]]
Historically, the monocotyledons were named:
* [[Monocotyledoneae]] in the [[de Candolle system]] and the [[Engler system]].
* [[Monocotyledones]] in the [[Bentham & Hooker system]] and the [[Wettstein system]]
* class [[Liliopsida]] in the [[Takhtajan system]] and the [[Cronquist system]].
* subclass [[Liliidae]] in the [[Dahlgren system]] and the [[Thorne system (1992)]].
* [[clade]] [[monocots]] in the [[APG system]] and the [[APG II system]].
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==
==References and external links==