Dicotyledon

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Dicotyledon
Lamium album (white dead nettle)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
Synonyms
  • Dicotyledoneae
Young castor oil plant showing its prominent two embryonic leaves (cotyledons), that differ from the adult leaves.

The dicotyledons, also known as dicots, were one of the two groups of flowering plants or angiosperms. The name refers to one of the characteristics of the group, namely that the seed has two embryonic leaves or cotyledons. There are around 200,000 species in this group.[1] The other group of flowering plants were called monocotyledons or monocots, with one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.

From the 1990s onwards, molecular phylogeny showed what botanists already suspected: dicotyledons are not a monophyletic group. They are a number of lineages, such as the magnoliids. Groups now known as basal angiosperms diverged earlier than the monocots did. The traditional dicots are a paraphyletic group. The largest clade of the dicotyledons are known as the eudicots. They are definitely monophyletic. They are distinguished from all other flowering plants by the structure of their pollen. Other dicotyledons and monocotyledons have an older type of pollen, whereas eudicots have derived pollen.

Compared to monocotyledons[change | change source]

Apart from cotyledon number, there are other differences between monocots and dicots. These are differences mainly between monocots and eudicots. Many early-diverging dicot groups have "monocot" characteristics such as scattered vascular bundles, trimerous flowers, and old-type pollen.[2] Also, some monocots have dicot characteristics such as reticulated leaf veins.[2]

Feature In monocots In dicots
Number of parts of each flower In threes (flowers
are trimerous)
In fours or fives
Number of furrows or pores in pollen One Three
Number of cotyledons
(leaves in the seed)
One Two
Arrangement of vascular
bundles in the stem
Scattered In concentric circles
Roots Develop from
various places
Develop from the
bottom of seedling
Arrangement of major leaf veins Parallel Reticulate
Secondary growth
thickens stem
Absent Often present

Related pages[change | change source]

References[change | change source]

  1. Hamilton, Alan; Hamilton, Patrick (2006), Plant conservation : an ecosystem approach, London: Earthscan, pp. 2, ISBN 978-1-84407-083-1, https://books.google.com/?id=P6m0OTheY8sC&printsec=frontcover#PPA2,M1
  2. 2.0 2.1 "Monocots versus Dicots". University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html. Retrieved 25 January 2012.