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Orchidaceae

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Orchidaceae


Color plate from Ernst Haeckel's
Kunstformen der Natur

Scientific Classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Liliopsida
Order: Asparagales
Family: Orchidaceae
Juss.
Sub Families
Apostasioideae
Cypripedioideae
Epidendroideae
Orchidoideae
Vanilloideae

Orchidaceae, also called the Orchid family, is the largest family of the flowering plants (Angiospermae). [1] [2]

Contents

[edit] Genera

For list of genera see List of Orchidaceae genera

The Royal Botanical Gardens of Kew list 880 genera and nearly 22,000 accepted species, but the exact number is unknown (perhaps as much as 25,000) [3] because classification varies greatly in different segments of the academic world. The number of orchid species equals about four times the number of mammal and bird species together. It also encompasses about 6 - 11 % of all seed plants [4] About 800 new orchid species are added each year. The largest genera are Bulbophyllum (2,000 species), Epidendrum (1,500 species), Dendrobium (1,400 species) and Pleurothallis (1,000 species). The family also includes the Vanilla (the genus of the vanilla plant), Orchis (type genus) and many commonly cultivated plants like some Phalaenopsis or Cattleya.

Moreover, since the introduction of tropical species in the 19th century, horticulturists have more than 100,000 hybrids and cultivars.

[edit] Distribution

Orchidaceae are cosmopolitan, occurring in almost every habitat apart from deserts and glaciers. The great majority are to be found in the tropics, mostly Asia, South America and Central America. They are found above the Arctic Circle, in southern Patagonia and even on Macquarie Island, close to Antarctica.

The following list gives a rough overview of their distribution:

  • tropical America: 300 to 350 genera
  • tropical Asia: 250 to 300 genera
  • tropical Africa: 125 to 150 genera
  • Oceania: 50 to 70 genera
  • Europe and temperate Asia: 40 to 60 genera
  • North America: 20 to 30 genera

[edit] Morphology

For details see Orchid Morphology

The basic orchid flower structure is composed of three sepals and two petals with a lip or labellum. The flower is usually bilaterally symmetric and a column which holds the pollina in the center.

Plants can be divided into two growth habits monopodial and sympodial. Sympodial orchids have a lateral growth habit while monopodial orchids grow up from a single point.

[edit] Naming

Orchids obtain their name of Greek "orchis", meaning "testicle", for the appearance of the underground tubercles in some terrestrial species. Its name is derived from the genus Orchis. The word "orchis" used Theophrastus for the first time (371/372 - 287/286 B.C.), in his book "De Historia Plantarum" (On the Natural History of Plants). He was student of Aristotle and it is considered the father of botany and ecology.

[edit] Taxonomy

For more information see Taxonomy of the Orchids

This family is universally recognised, and the APG II system of 2003 places it in the order Asparagales.

The taxonomy of this family is in constant flux, as new studies continue to identify more classificatory elements.

Five subfamilies are now recognised. The cladogram has been made according to the APG system:



Apostasioideae: 2 genera and 16 species, south-western Asia




Cypripedioideae: 5 genera and 130 species, mostly from the temperate regions of the world, some in tropical America


 Monandrae 

Vanilloideae: 15 genera and 180 species, humid tropical and subtropical regions, eastern North America




Epidendroideae: more than 500 genera and more or less 20 000 species, cosmopolitan



Orchidoideae: 208 genera and 3,630 species, cosmopolitan







[edit] Statistical Records

Largest orchid flower: Paphiopedilum sanderianum

Smallest orchid flower: Platystele jungermannioides

Largest orchid species: Grammatophyllum speciosum

Smallest orchid species: Bulbophyllum minutissimum

Largest genus: Bulbophyllum

[edit] Growing conditions

Orchids can be separated into five types of growing conditions.

  1. Aquatic - plants that grow in the water.
  2. Epiphyte - plants that grow on branches and mossy trees.
  3. Lithophyte - plants that grow in rock outcrops and in stone surfaces
  4. Saprophytes - grows in leaf litter and is usually dependent on mycorrhiza for nuitrience
  5. Terrestrial - plants that grow in sand, clay, or soil

[edit] References

  • Walter S. Judd, Christopher S. Campbell, Elizabeth A. Kellogg, Peter F. Stevens, Michael J. Donoghue: Plant Systematics: A Phylogenetic Approach, Sinauer Associates Inc. 2007
  • Batygina, T. B., Bragina, E. A., and Vasilyeva, E. 2003. The reproductive system and germination in orchids. Acta Biol. Cracov. ser. Bot. 45: 21-34.
  • Berg Pana, H. 2005. Handbuch der Orchideen-Namen. Dictionary of Orchid Names. Dizionario dei nomi delle orchidee. Ulmer, Stuttgart
  • Kreutz, C. A. J. 2004. Kompendium der Europaischen Orchideen. Catalogue of European Orchids. Kreutz Publishers, Landgraaf, Netherlands
  • Ramírez, S., et al. Nature 448 , 1042- 1045 (2007).
  • D. Lee Taylor and Thomas D. Bruns : Ectomycorrhizal mutualism by two nonphotosynthetic orchids; Proc. Natl. Acad. Sci. USA; Vol. 94, pp. 4510-4515, April 1997 (on line).
  • Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 7, May 2006 [and more or less continuously updated since]. [1]
  • Strasburger, Noll, Schenck, Schimper: Lehrbuch der Botanik für Hochschulen. 4. Auflage, Gustav Fischer, Jena 1900, p. 459

[edit] External links


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