Saturday, September 8, 2007

What's so special about orchids

Click on the image for enlarged view ...

To begin with, I had to look for the question ... What is an orchid??? ...

Orchids are the largest family of angiosperms [flowering plants] in the world. It has more than 1,000 genus and 30,000 species ... In fact 10% of all known species of flowering plants are orchids. Most familiar orchids are those found in tropical regions.

Orchids are considered the most evolved of the flowering plants. These plants have evolved to have specialized requirements for habitat. Each orchid species will germinate and grow only when these habitat requirements are optimal. Orchids are also unique in their methods of fertilization, seed production, germination, and pollination strategies.

* Orchids are considered monocots , distinguished from other angiosperms by having only one cotyledon, or the leaf that first emerges from the seed. Monocots typically have flower parts in groups of three or six, and this is exemplified by the structure of the orchid flower. Altough orchids display considerable polymorphy and structural diversity they have very similar floral pattern ...

* The perianth of an orchid flower consists of six tepals, which are arranged in two similar or dissimilar whorls ... Three sepals [outer floral whorls] and three petals [inner floral whorls] ... All the sepals are alike ... and the two lateral petals are also alike. But one of the three petals, is typically quite different from the others ... It is called labellum or lip ... It is usually larger and different in color and shape, often being lobed or cupped.

* The labellum, which often acts as a landing platform for the orchid pollinator, may attract the pollinator to the flower through particular color patterns and shapes to which the pollinator responds in particular ways. * Orchids are distinguished from other plants by fusion of their reproductive parts into a column [stamen-male & pistil-female], this column /stalk is found at the center of the flower, opposite the lip ... and is called gynostemium / column ...

* The pollen is not granular, as it is in most flowering plants, but is aggregated together in a number of masses, or sacs, that vary in texture from mealy to horny.

* The flowers are zygomorphic , which means they are bilaterally symmetric ...
* The flower stem twists around during development Orchids.
* The leaves of orchids are narrow and undivided ...

* All orchid species are reliant upon mycorrhizal associations with various fungi to complete their lifecycle. In general, orchid mycorrhizal fungi decompose organic matter and subsequently translocate the obtained nutrients via their hyphae to the orchid. Because most orchid seeds are extremely tiny with no food reserves (endosperm lacking), they will not germinate without such a symbiont to supply nutrients in the wild.* They grow from the Arctic to the Equator and south in all the continents except Antarctica.



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