Introduction Of Orchid

Orchids are renowned for their exquisitely beautiful and colorful flowers for which they are favourites of the flower lovers. Biologically complex plants as they are, they have equally drawn the attention of the botanists. The structure of the orchid plant as also the flower is very interesting. These are herbaceous plants with different growth habits. Some are terrestrial, i.e. grow on soil preparing their own food; some others derive their nutrient requirement directly from decaying material in the substrate and are saprophytes. But the majorities of them adopt a superterranean or aerial mode of living over trunks or branches of other plants, and thus, are known as epiphytes. They however prepare their own food and are never dependent on the host.

Orchids are very widely distributed over the globe except in the extreme hot or cold regions. To accommodate to the widely varying range of environmental factors, in a very large geographical area, the vegetative habits in the terrestrial forms have undergone enormous changes. The aerial existence of the epiphytic forms, although distributed in a comparatively smaller area than the terrestrials, too, necessitated highly varying modification in their vegetative forms. The plant structure in orchids is thus remarkably diverse and few other plant families match their vegetative diversity.

Orchids are a strange group of plants standing apart from the rest of the plant families. This is how they are. An orchid fruit contains inside it innumerable dust-like non-endospermic seeds. The peculiar mode of germination of these seeds require the association usually with mycorrhizal fungi. The presence of air space in the seed makes it lighter and buoyant to be dispersed over a wide geographical area. Orchid roots are covered with spongy dead cells called velamen, which protects the inner conductive channel, absorbs moisture from the air and clings to the host tree securing a strong position for the plant.

Flowers of orchids are found in incredible ranges of size, shape, colour and ornamentation. But it is the mode of construction of the flower and its efficiency in successfully carrying out the intended functions through the various floral organs that render orchids the wondrous creation of nature. The orchid flower has evolved many complexities for perfecting cross- pollination. This is easily noticeable in its flower structure. For example, the otherwise inconspicuous sepals have become colored like petals and one of the three petals, known as the lip, is variously shaped and decorated. By an extreme torsion or twisting of the pedicellate ovary through an angle of  flowering, the lip occupies a frontal position so as to serve as a landing platform for the visiting pollinator.

The pollen grains are agglutinated into neat little packets known as pollinia. The pollinia aim at fertilizing a very large number of ovules while avoiding unnecessary wastage of the pollens. The pollinia is provided with accessories by which it gets attached to the body of the pollinator. It is kept inside a pouch on top of a stump-like structure known as the column, in such an easily accessible position that, the foraging insect while probing the flower, would not fail to dislocate the pollinia and carry it way. The column has evolved through the fusion of the style and the filament The stigma, the female receptive organ, is suitably crafted, usually, on face of the column. The column is a unique and characteristic structure of the orchid flower.

An interesting feature of the orchid flower is the striking resemblance of many of them to various animal forms like bee, wasp, butterfly, moth, scorpion, frog, dove, tiger or even man (man orchid). Sometimes they adopt odd posture and attain popular names such as laughing orchid, soldier orchid, flying duck orchid and ghost orchid.

The diversity in their structure, the aerial existence and capability of survival in varying climatic condition show their adaptive excellence. This explains why Orchidaceae, largest among the flowering families with around successful and advanced in the plant kingdom. As an advanced family, orchids have tolerated wide crosses to allow free gene flow across specific limits, within and between the genera, to enable them move faster by strides in the path of evolution. Production of new species by hybridization is the speediest form of their evolution. Natural hybrids among orchids have been reported from early days of orchid collection. But it is the stupendously large number of man-made hybrids that have surpassed the scale of imagination. The artificial hybrids have flowers more beautiful than anything found in the nature. This aspect has been taken advantage of in the horticultural pursuit for better quality of flowers. Orchid cut-flowers, with better keeping quality (flowers remain fresh for months), now a days abundantly available, has become a very successful and alluring trade in the global market of floriculture.

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