Orchid

Orchidaceae
Cypripedium reginae
Scientific classification
Domain: Eukaryota Kingdom: Plantae Division: Magnoliophyta Class: Liliopsida Order: Asparagales Family: Orchidaceae Juss. 1789
Type genus
Orchis L. 1753
Subfamilies
Apostasioideae Garay 1960 Vanilloideae Szlach. 1995 Cypripedioideae Garay 1960 Orchidoideae Eaton 1836 Epidendroideae Lindl. 1821
Synonyms
Apostasiaceae Lindl. 1833 Cypripediaceae Lindl. 1833 Limodoraceae Horan. 1847 Neottiaceae Horan. 1834 Vanillaceae Lindl. 1835 Neuwiediaceae (Burns-Balogh & Funk) R.Dahlgren ex Reveal & Hoogland 1991

There are literally tens of thousands of species, cultivars and varieties in the orchid family, the largest family of flowering plants. The word orchid may refer to any of the botanical family Orchidaceae, or, more commonly among lay persons, any of thousands of flowers called "orchids".

Orchids are ancient, and have been cultivated for centuries. They range from rare and recent discoveries such as the tiny Tallong Midge Orchid to the large, showy orchids which are featured in bouquets and corsages, to food orchids such as vanilla. A few orchids have insignificant flowers and are grown for their foliage.

Orchids seemed to be fascinating: every developed nation has many orchid societies, and this fascination extends beyond form and beauty. Because of their biological importance (some orchids have developed extraordinary systems of pollination, for example, "Lady's Slipper" traps insects and so forces them to pollinate the flower; one Australian orchid exists underground and is pollinated by ants; many give off attractive odours), orchids hold just as much interest for scientists. Famed biologist Ernst Mayr discovered and named 38 new species of orchid.

Distribution

Despite their distribution is largely irregular throughout the globe, orchids can be found in almost all regions of the planet, except Antartic continet. Due to their wide greographic distribution, it is natural that a so diverse group of plants show high degree of adaptation to different climates and to the multiplicity of polinators present in each area. Orchidaceae is a family passing through an active cycle of evoluctionary development. Traditionaly, Biology considers the species concept as a group of beings that can breed producing fertile descendants. Orchid species are slightly different because they do not fit well in this concept. Not only most of the species can interbreed with several other producing fertile descendants, as most of the genera that belong to the same subtribe can do too. It is not uncommon to encounter natural hybrids between diferent species and genera in the wild, and although almost all these plants are fertile, the are not more common just because as orchids are highly adaptated to their polinator, these hybrids may occur by chance and their particular resulting morphology are not really adaptated to the existing polinators. There are some rare exceptions, when these hybrids are result of breedings of two closely related species and still can be polinated by the same polinators of parent species. When this happens it is more likely that along the years a new species can appear. This may be the case of Cattleya × mesquitae. It is a natural hybrid discovered in 1996 in Goiás State in Brazil. We know know that this species is a result of a high degree of interbreeding of Cattleya walkeriana and Cattleya nobilior. As the result of this breeding is pollinated by the same agents of its parents, the crossing has been occuring again and again between the three species from the area along the ages, thus one of the original parents cannot be found there anymore. All original plants have crossed and faded. Today we know Cattleya × mesquitae is a hybrid because similar plants have been procuced by artificial breedings. Lou Menezes, its describer, claims that this species is so ancient that they have even evolved in nature, developing a fragrance that is not present on the hybrids artificially produced. This is one of the ways a new species can appear in ithe wild. Cases like this are not uncommon among orchids, therefore many species are hard to circunscribe exactly because they result of different degrees of breedings between closely related species in a given area.

The number of orchid genera that exist on every continent is not exact because there is no consensus among the taxonomists about how to split them, however, it can be estimated as follow: Eurasia, about 50 genera; North America, circa 25 genera, Latin America and Caribbean, between 300 and 350; tropical Asia, between 250 and 300; tropical Africa, circa 250; and Oceania, about 60.

The largest diversity of orchid species occurs in tropical areas of the globe, notably on mountain areas, which are natural bareers that insolate the several populations of plants. Islands also favor development of species but unlikely mountain areas, islands do not favor diversity that much because, unless the island is large enough to have a variety of climates, what is more commen is to find a high number of few endemic species that do not exist anywhere else. Exceptions are large islands as Borneo, New Guinea, Madagascar and some other, where the diversity is enormous, these have both a high number of endemisms and wealthy of different species. Therefore, some of the main areas in the world noted for having a large number of species are the Islands os Southeast Asia, the mountain areas of Ecuador and Colombia and the Atlantic Jungle along Brazilian coastal mountains, where there are more than fifteen hundred species. Other important diversity areas are the mountains of Mesoamerica and the ones south of Himalaya, in India and China, besides the southeast of Africa, particularly Madagascar. Ecuador is the country where the largest number of orchid species is reported, up to 3,549, imediately followed by Colombia, with 2,723, New Guinea, 2,717, and Brazil, with a total of 2,590. Among others, Borneo, Sumatra, Madagascar, Venezuela and Costa Rica, are countries with high number of species.

Habit

The most common kinds of orchids in each of these areas are highly variable. On tropical regions, where the humidity is high, yet the competition for light with tree species is strong, the orchids tent to be predominat epiphytical, however, many species ot terrestrial species, able to thrive without high amounts of light do exist too. Looking for light, under the shadow of trees up to forty meters tall, this herbs grow over their branches and stems, at diverse heights, according to the necessities of each species. Their roots, exposed to the air, obtain most ot the nutrients from decaying material that acumulates around them, from the rains that washes the tree leaves from above, or from the air dust. Orchid roots are recovered by a spongy tissue called velamen. Associated with the velamen, most of orchids host a fungus known as Mycorrhyza that helps on decomposing of organic material breaking them into mineral salts, making easier their absortion by orchids. In extreem conditions, orchids may to some extent, absorve water and nutrients thorough the pores on their leaves, leaving to the roots only the function of sustaining the plant attached to the substract. No orchid is a parasite, what means their presence never damages their hosts, despite, in exceptional cases, some tree branches may not be strong enough to sustain the weight of a large colony and may end broken. There are many terrestrial orchids on tropical areas too, although, differently form the ones from temperate regions, many may keep growing almost constantly during most of the year. The great amount of organic material available on forests soil favors the occurence of few saprophytic species of orchids without chlorophyll, which obtain all their nutrients from substances rejected by the processing of decomposing material by fungi associated to them.