**Characteristics of Dicotyledons:**
– Dicotyledons are one of two groups of flowering plants.
– They are characterized by having two embryonic leaves.
– There are approximately 200,000 species within this group.
– Eudicots are the largest monophyletic group within dicotyledons.
– Eudicots are distinguished by the structure of their pollen.
**Comparison with Monocotyledons:**
– Broad differences exist between monocots and dicots.
– Early-diverging dicot groups may have monocot characteristics.
– Some monocots exhibit dicot characteristics.
– The remaining dicots may be classified as palaeodicots or basal angiosperms.
– Some botanists argue for retaining dicotyledons as a valid class.
**APG vs. Cronquist System:**
– The APG IV system and Cronquist system categorize dicots differently.
– The orders in the APG IV system are traditionally called dicots.
– The classification of dicots has evolved over time.
– The Cronquist system is an older classification system.
– Taxonomic classification of dicots has been a subject of debate.
**Evolutionary Relationships:**
– Molecular phylogenetic research has shown dicotyledons are not monophyletic.
– Monocots evolved from within the dicots.
– The traditional dicots are a paraphyletic group.
– Magnoliids and basal angiosperms diverged earlier than monocots.
– Eudicots have tricolpate pollen, distinguishing them from other flowering plants.
**External Links:**
– Wikispecies provides information related to Magnoliopsida.
– The World list of dicot species contains 253,406 species.
– External resources can provide further information on dicotyledons.
– Research and databases offer insights into the diversity of dicots.
– Accessing external links can enhance understanding of dicotyledons.
The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, that the seed has two embryonic leaves or cotyledons. There are around 200,000 species within this group. The other group of flowering plants were called monocotyledons (or monocots), typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.
| Dicotyledon | |
|---|---|
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| Lamium album (white dead nettle) | |
Scientific classification
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Spermatophytes |
| Clade: | Angiosperms |
| Groups included | |
| Cladistically included but traditionally excluded taxa | |
| Synonyms | |
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Largely from the 1990s onwards, molecular phylogenetic research confirmed what had already been suspected: that dicotyledons are not a group made up of all the descendants of a common ancestor (i.e., they are not a monophyletic group). Rather, a number of lineages, such as the magnoliids and groups now collectively known as the basal angiosperms, diverged earlier than the monocots did; in other words, monocots evolved from within the dicots, as traditionally defined. The traditional dicots are thus a paraphyletic group.
The eudicots are the largest monophyletic group within the dicotyledons. They are distinguished from all other flowering plants by the structure of their pollen. Other dicotyledons and the monocotyledons have monosulcate pollen (or derived forms): grains with a single sulcus. Contrastingly, eudicots have tricolpate pollen (or derived forms): grains with three or more pores set in furrows called colpi.