Flowering plant (original) (raw)

The flowering plants are one of the major groups of modern plants, comprising those whose seeds are produced in an enclosed ovulary or carpel, a specialized organ of reproduction we call a flower. The carpel may go on to develop into a fruit, for which the plants are often called angiosperms ("vessel seeds"). In other seed-bearing plants, called gymnosperms, the ovule is not enclosed, and they do not produce fruit. The angiosperms first appeared at least 140 million years ago, during the Jurassic period, but may have diverged from the gymnosperms even earlier, in the Triassic period.

Flowering plants are usually treated as a division, formerly called the Angiospermophyta or Anthophyta, but now called Magnoliophyta after the type genus Magnolia. The main split within the Division Magnoliophyta is between the dicotyledons and monocotyledons (or dicots and monocots for short). The names come from the number of embryonic leaves, called cotyledons, found within the seed, but there are other notable differences (see "How to distinguish a monocot from a dicot"). The dicots are now considered a paraphyletic group, though most belong to a monophyletic subgroup called the eudicots or tricolpates.

The classification of flowering plants has undergone considerable revision as ideas about their relationships change. The classification given by Arthur Cronquist (1981) is widely used. Although many of the proposed groupings have been questioned, a general consensus has started to emerge about what the breakdown of the Magnoliophyta should look like.

The most common families of flowering plants, in order of number of species, are:

1. Asteraceae (daisy family): 25,000 species
2. Orchidaceae (orchid family): 18,000
3. Fabaceae (pea family): 17,000
4. Poaceae (grass family): 9,000
5. Rubiaceae (coffee family): 7,000
6. Euphorbiaceae (spurge family): 5,000
7. Cyperaceae (sedge family): 4,000

In the list above (showing only the 7 largest families), the Orchidaceae, Poaceae, and Cyperaceae are monocot families; the others are diciot families. The total number of families in the Magnoliophyta is over 460.

See Also

• List of flowers

References and External Links

Cronquist, Arthur. (1981) An Integrated System of Classification of Flowering Plants. Columbia Univ. Press, New York.

• Tree of Life Web Project ~ Angiosperms
• Oldest Known Flowering Plants Identified By Genes, William J. Cromie, Harvard Gazette, December 16, 1999.
• Missouri Botanical Garden
• Delta Families of Flowering Plants
• Flower Pictures