Dicotyledon
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Dicotyledons, or "dicots", is a name for a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group [1]. Flowering plants that are not dicotyledons are monocotyledons, typically having one embryonic leaf.
The dicotyledons no longer are regarded as a "good" group, and the names "dicotyledons" and "dicots" are no longer to be used at least in a taxonomic sense. The vast majority of the former dicots, however, form a monophyletic group called the eudicots or tricolpates. These may be distinguished from all other flowering plants by the structure of their pollen. 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 Magnolia. 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.
[edit] Classification
The following lists are of the orders formerly placed in the dicots, giving their new placement in the APG-system and that under the older Cronquist system, which is still in wide use.
