Theophrastus, the father of botany (370 -285 BC) named "ORCHIDS" on the basis of the resemblance of paired underground tubers to masculine anatomy (the testes). They shows fascination for their beautiful flowers. They represent to the family Orchidaceae, the most highly evolved family among monocotyledons with 600 to 800 genera and 25,000-35,000 species in the world. They are peculiar and are highly valued in the international market.
Majorly orchids are are native to tropical countries, like America, Asia and Australia. In India, they constitute 9% of our flora and are generally homed to Himalayas, and to some extent at Eastern and Western Ghats. About 1,300 species of about 190 genera are found in India. Brazilian Cattleyas, Mexican Laelias and Indian Dendrobiums, Cymbidiums and Vandas played a major role in the development of modern orchid industry in the world.
Orchids can be divided into two groups - monopodial (plants grows every year with a single stem) and sympodial (plants produces every year a new shoot) depending upon their habit of growth. On the basis of climatic requirements, they are grouped as:
1. Tropical orchids.
2. Subtropical orchids (800-1850 m altitude) Eg. Phaius, Coelogyne, Cymbidium, Dendrobium, Calanthe etc.
3. Temperate orchids. (1850-3500 m altitude) Eg. Pleione, Paphiopedilum, Satyrium, Cymbidium, Hervinium etc.
4. Alpine orchids (3500-5000 m altitude) or ground orchids.
Morphologically orchids are perennial herbs with simple leaves. The specialized flower structure conforms to a standard plan, the vegetative parts shows great variation, i.e. may be epiphyte, terrestrial, saprophytic or leafless in nature. Epiphytic orchid plants can be cultivated on live Trunks or branches. Eg. Vanda tessellate, Wooden Blocks, or baskets and bamboo-splits, as well as in pot or bed.
Orchids have bilaterally symmetrical (Zygomorphic) flowers with an inferior ovary. Among all petals, the 3rd petal is labellum or the lip. It helps in attracting and supporting the pollinating insect and is responsible for different names like `Frog orchid', `Dove orchid', `Spider orchid', `Lady slipper orchid' etc. The reproductive organs, stamens and pistil, are condensed and forms a consolidated complex body, the 'column', both part being separated by a flap or projection called rostellum. Each flower has one, two or rarely three stamens. Their pollen grain coheres in the pollinia. Orchids are generally propagated by off-shoots, splitting, back-bulbs, top-cuttings, seed culture and tissue culture. Hybridization is generally performed by pollination.
The most interesting and adaptive feature of the family Orchidaceae is the physiology of its seed germination. Orchid seeds are exceedingly small, dust like and are produced in very large numbers i.e. 1,300 to 4,00,000 seeds per capsules. Their colour and shape varies. Under natural conditions, their seed germinates after being infected by fungus, the orchid mycorrhiza (coined by Frank in 1885) and mostly belongs to a non-sporing group Rhizoctonia. In Japan 54 different fungi were isolated from 20 orchid species. Utmost care is required during their cultivation. It all depends depends on local climatic conditions like high rainfall and relative humidity other than macro and micronutrients, favours orchid growth. Water stagnation and direct sunlight with high intensity retards their distribution. This may be the reason for their high endemism.
Some ornamental indian species: Aerides crispum, A. fieldingii, A. multiflorum, A. odoratum, Anaectochilus roxburghii, Arachnis clarkei, Arundina graminifolio, Bulbophyllum leopardinum, Calanthe masuca, Coelogyne elatn, C. devonianum, Cymbidium pendulum, C. longifolium, C. munronianum, Dendrobium aggregatum, D. aphyllum, D. fimbriatum, D. jenkinsii, D. moschatum, D. nobile, Paphiopedilum faireanum, P. venstum, P. hirsutissium, p. insigne, Phaius wallichii, Pleione praecox, Rhynchostylis retusa, Thunia alba, Vanda cristata, and V. coerulescens.
ORCHIDS WITH MEDICINAL IMPORTANCE
In India, orchids are employed for a variety of therapeutic use in different systems of traditional medicines like Ayurveda, Siddha and Unani. Some are mentioned as follows:
Species - Disease
Acampe praemorsa - Rheumatism
Habenaria's - Unconsciousness, vermicide and as blood purifier
Cymbidium aloifolium - Emetic and purgative
Dendrobium ovatum - Stomach ache
Eulophia nuda - Tumors and bronchitis
Flickingeria nodosa - Astringent, aphrodisiac, expectorant
Luisia zeylanica - Emollient for boils, abscess and burns
Of the world's 30,000 orchid species, some 10% (3,000) are believed to be endangered in their native habitats due to the physical destruction of habitat and over-collection. An example is Paphiopedilum druryi, found in Agastaya Hills in South India, is now difficult to locate.
CONSERVATION OF ORCHIDS
The convention of International Trade in Endangered Species of Fauna and Flora (CITES), ratified by India, places all species of Orchidaceae under Appendix II, meaning that their trade will be only through export permits. Steps have also been taken to conserve Indian native species by establishing Orchidaria, sanctuaries and germplasm conservation centres. Botanical survey of India has established Orchidaria at Shillong and Yercaud to conserve rare and endangered species. In Sikkim orchid sanctuaries at Singtom and Deorali and in Arunachal Pradesh at Tapi are established.
Orchids are currently the second most valuable potted crop. The largest exporters of potted orchids include Taiwan, Thailand, the United Kingdom, Italy, Japan, New Zealand and Brazil, while the largest importer of potted orchids is the United States.
To recognize the global importance of orchids as potted flowering plants, an orchid research program was initiated at Michigan State University with a goal to elucidate the flowering requirements for several orchid species and to use this information to develop necessary production protocols for commercial growers.
Similar to other potted plants, flowering orchids are much more marketable and commercially valuable than plants without flowers. They can be stored at low temperature upto 00. However, scientific research on orchid growth and development has been limited to a few species and commercial production information is only available for hybrids of the genus Phalaenopsis. Research has been conducted on many economically important floriculture crops such as chrysanthemums, Easter lilies, and poinsettias and production schedules have been developed. Although orchids are one of the most commercially valuable flowering plants in the world, with some notable exceptions (e.g., Phalaenopsis and Cymbidium), knowledge of the flowering process for the vast majority of species is unknown. Limited scientific research has been performed on controlled greenhouse production. Common growing temperatures range from 10 to 29 °C (50 to 84 °F).
The primary goal of orchid research program is to understand how environmental parameters (e.g. temperature and light) influence growth and development of species. The new techniques will be developed to disseminate the production schedules to commercial growers, which will allow orchids to be produced in controlled greenhouses in a uniform manner.
In addition to our stated research objectives, there is flexibility to research and focus on other aspects of orchid production, such as nutrition, postharvest handling, marketing, and pest management.
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