 | Flowering plant: Encyclopedia II - Flowering plant - Classification
Flowering plant - Classification
The flowering plants are usually treated as a division. As this is a group above the rank of family there is a free choice of name: Art 16 of the ICBN allows either a descriptive name or a name based on a generic name. The favorite name in the latter category is Magnoliophyta (at the rank of division, based on the Magnolia. The most popular descriptive name is Angiospermae (Angiosperms), with Anthophyta ("flowering plants") a second choice.
The internal classification of this group has undergone considerable revision as ideas about their relationships change. The Cronquist system, proposed by Arthur Cronquist in 1981, is still widely used but is no longer believed to reflect phylogeny. A general consensus about how the flowering plants should be arranged has only recently begun to emerge, through the work of the Angiosperm Phylogeny Group, who published an influential reclassification of the angiosperms in 1998. An update incorporating more recent research was published as APG (2003) and is available at the Wikipedia Tree of Life/Update of the Angiosperm Phylogeny Group.
Traditionally, the flowering plants are divided into two groups, which in the Cronquist system are called Magnoliopsida (at the rank of class, based on Magnolia) and Liliopsida (at the rank of class, based on Lilium). Much more popular are their descriptive names (as allowed by Art 16 of the ICBN): Dicotyledones (some prefer Dicotyledoneae) and Monocotyledones (some prefer Monocotyledoneae), which have been in use for very long. In English a member of either group may be called a "dicotyledon" (plural "dicotyledons") and "monocotyledon" (plural "monocotyledons"), or more popularly "dicot" (plural "dicots") and "monocot" (plural "monocots"). These names derive from the fact that the dicots often (but not always) have two cotyledons (embryonic leaves) within each seed, while the monocots typically will have one only. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character.
Recent studies show that the monocots are a "good" group (a holophyletic or monophyletic group), while the dicots are not (a paraphyletic group). However, within the dicots a "good" group exists, which includes most of the dicots. This new group is semi-informally called the "eudicots" or "tricolpates". The name "tricolpates" derives from the type of pollen found throughout this group. The name eudicots is formed by preceding "dicot" by the prefix "eu-" (greek 'eu'= "true"), as the eudicots share the characters traditionally attributed to the dicots, such a four- or five-merous flowers. The uninitiate may be tempted to jump to the conclusion that "eudicot" is short for "eudicotyledon" but it is not: the name is eudicot. A formal name that is sometimes used for this group is Rosopsida (at the rank of class, based on Rosa). Separating this group of eudicots from the rest of the (former) dicots leaves a remainder, which sometimes are called informally "palaeodicots" (the prefix "palaeo-" means old, and derives from the classic greek). As this remainder group is not a "good" group this is a term of convenience only.
Flowering plant - Families of flowering plants
The most diverse families of flowering plants, in order of number of species, are:
- Asteraceae or Compositae (Daisy family): 26,000 species
- Orchidaceae (Orchid family): 20,000 (possibly 30,000)
- Fabaceae or Leguminosae (Pea family): 17,000
- Poaceae or Gramineae (Grass family): 9,000
- Rubiaceae (Madder family): 7,000
- Euphorbiaceae (Spurge family): 5,000
- Malvaceae (Mallow family): 4,300
- Cyperaceae (Sedge family): 4,000
In the list above (showing only the 8 largest families), the Orchidaceae, Poaceae, and Cyperaceae are monocot families; the others are dicot families. The total number of families in the flowering plants is over 460.
Other related archives1690, 1851, Angiosperm Phylogeny Group, Apiaceae, Arthur Cronquist, Asteraceae, Brassicaceae, Carolus Linnaeus, Cocos nucifera, Coniferae, Cretaceous, Cronquist system, Cryptogamia, Cucurbitaceae, Cycadeae, Cyperaceae, Daisy, Euphorbiaceae, Fabaceae, Flower, Gnetophytes, Greek, Gymnosperms, ICBN, Jurassic, Liliopsida, List of flowers, Madder, Magnolia, Magnoliopsida, Mallow, Malvaceae, Mediterranean, Olea europaea, Orchid, Orchidaceae, Parthenogenesis, Pea, Plant sexuality, Poaceae, Robert Brown, Rosaceae, Rubiaceae, Rutaceae, Solanaceae, Spurge, Taxus, Triassic, Wikipedia Tree of Life/Update of the Angiosperm Phylogeny Group, apples, apricots, atolls, barley, beech, cabbage, camphor, carpel, cherries, cotton, cotyledons, dicotyledon, digitalis, division, elms, endosperm, eudicots, female gamete, fertilization, flax, flower, fruit, gourd, gymnosperms, hemp, hermaphrodite, holophyletic, inflorescence, leaves, magnolia, maize, maple, melons, millet, monocotyledon, monophyletic, mustard, oak, oats, organs, ovule, palaeodicots, paper, paraphyletic, parsley, pears, peppers, petals, plants, plums, pollen, pollen-grains, pollinators, poplars, potatoes, pumpkins, rapeseed, rice, rye, seed plants, seeds, self-incompatibility, sepals, sorghum, spores, stamen, stamens, sugar cane, tomatoes, tricolpates, wheat, willow, wood
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