Powered by Blogger.

Saturday, October 9, 2010

Paphiopedilum and other orchids

No comments :

Paphiopedilum is an orchid with unusual form of flowers. Some of these are epiphytes while others are lithophytes. It has a peculiar pouch which collects insects and contributes in pollination. It is due to fascinating shapes and colours of orchids that these are smuggled and collected on large scales. Though these orchids are protected under international law, the existence of these plants has become seriously threatened.

Paphiopedilum is a genus often abbreviated as Paph belonging to the family Orchidaceae.This family contains about 80 species some of which has been developed through hybridization in nature.

Paphiopedilum, the genus was named by Ernst Hugo Heinrich Pfitzer in 1886. This name is derived from the name of a city of Cyprus – Paphos; and the ancient Greek Word “pedilon” meaning “slipper”. In fact no Paphiopedilum grows on Cyprus. It was finally decided in 1959 that Paphiopedilum should be the name of the taxon.

Paphiopedilum is native to India, China, Southeast Asia and the Pacific islands. The species naturally occurs among humus layers on the floors of forests. Some species are epiphytes where as others are lithophytes. The leaves of these plants are short, rounded, or long and narrow. Roots of the plant are thick and fleshy. When potted, these plants form tight lumps of roots. Some of the roots grow up to a length of even 10 meters. The adult plant produces a shoot which produces a raceme inflorescence.

The Orchid Diversity
Paphiopedilum are wifely cultivated and hybridized plants, as these are easy to grow indoors as long as favorable conditions remain available.P. armeniacum is an endangered species which is native to China.

India has a very large variety of orchids and hilly regions have one or the other orchid flowering almost throughout the year. The diversity is so large that there are terrestrial, epiphytic and also saprophytic orchids. In general terrestrial orchids are more common in Northwestern India, epiphytic orchids in North-Eastern India and small flowered orchids in Western Ghats. The largest terrestrial genus is Habenaria and the largest epiphytic genus is Dendrobium . Most of the Paphiopedilum (lady's slipper) species are restricted to N.E Himalayas except for P. druryi . This species, which had been reported from Kerala was thought to be almost extinct from its original habitat and was recently rediscovered.

Ornamental Orchids
Some of the Indian orchid species which are of high ornamental value are : 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, V. coerulea and V. coerulescens.

Ecological Status
Of the world's 30,000 orchid species, some 10% (3,000) are believed to be endangered in their native habitats. There are two major causes; the primary threat is from the physical destruction of habitat. Clearance of natural vegetation for timber, crop cultivation or forestry, or for industrial or urban development has decimated uncounted species from Indonesia to Brazil. Habitat destruction not only destroys the places for the plants to live, but also causes loss of the orchid's pollinators, other plants, and fungi that they depend on. The other threat is also man-caused such as over-collection. Despite bans in many countries on the collection and export of native plants, in many cases the damage to the population is already beyond repair and there is still a trade from unscrupulous orchid growers. A large number of orchid species, which were present in plenty in Indian forests, are now at the verge of extinction and some of them have become so rare that a large number of botanical teams were unable to trace them. To cite an example Paphiopedilum druryi , which was once found in plenty in Agastaya Hills in south India, is now difficult to locate.

Some orchids are endemic to India are so ornamental and in demand that their natural populations have been over exploited. Some species in the genera like Arundina , Cymbidium, Coelogyne, Dendrobium, Paphiopedilum, Renanthera, and Vanda are almost extinct. The provisional list of 150 endangered plants of India includes many orchids like Acanthephippium sylhetense, Anoectochilus sikkimensis, Aphyllorchis montana, Arachnanthe clarkei, Arundina graminifolio, Cymbidium macrorhizon, Dendrobium densiforum, Didiciea cunninghamii, Eria crassicaulis, Galeola lindleyana, Gastrodia Exilis, Paphiopedilum fairanum, P. druryi, Pleione humilis, Renanthera imschootiana, Vanda coerulea, V. pumila and Vroxburghi.

Orchids are specific to their habitats, this is to say – these are highly endemic.The high endemism in orchids is perhaps because of certain physiological adaptive condition of the family bringing greater constrains on their existence, spread and replenishment in any particular area, for example –

(i).Their existence in specific niches within the fragile ecosystem.

(ii).Insect pollination in most of the species, particularly needing specific vectors to visit different species.

(iii).Inability to achieve fertilization in maximum number of ovules for viable seeds due to the fact that each ovary of the orchid possesses millions of ovules.

(iv).Presence of an unorganized embryo in the seed, also without any food storage and hence needing infection of a specific strain/race of mycorrhiza as a food supplier before germination.

(v).Absence of similar habitats for orchid seedlings/propagules to pass through similar niches for establishment and dispersal.

Taking care of Orchids
The list of plants banned or restricted for export from India formerly included a few orchids but now include all orchids growing wild. 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 thereby 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 two Orchidaria one at Shillong and other at Yercaud to conserve rare and endangered species. The ICAR research complex at Shillong, the Indian Institute of Horticultural Research at Hessaraghatta and the Indian Botanic Gardens at Calcutta maintain collections of orchids in their Orchidaria. Some states have also established orchid sanctuaries in Sikkim at Singtom and Deorali and in Arunachal Pradesh at Tapi6. However, the concept of in situ conservation in the wild condition of the existing rich orchid flora at their nativity is rather lacking. Hence, there should be selection of areas rich in orchids as ‘orchid preserves' at sectoral levels in the hot spot areas to prevent deforestation, habitat destruction, and indiscriminate collection by orchid lovers and exploitation by tradesmen.

·   Cooke, T. (1901-1908). Flora of Presidency of Bombay, 3 Vols. Taylor and Francis, London.
·   Gamble, J. S. 1915-1936. Flora of the Presidency of Madras, Adlard and Son, London.
·      Harley J.L., S.E.Smith, 1983. Mycorrhizal Symbiosis. Academic press Inc., London.
·      Rao Anand T., 1998. Conservation Of Wild Orchids Of Kodagu In The Western Ghats. The Karnataka Association for the Advancement of Science, Bangalore.
·      Braem, G.J.; Baker, Charles O. & Baker, Margaret L. (1998): The Genus Paphiopedilum: Natural History and Cultivation (Vol. 1). Botanical Publishers Inc., Kissimmee, Florida, USA.
·      Leroy-Terquem, Gerald & Parisot, Jean (1991): Orchids: Care and Cultivation. Cassel Publishers Ltd., London, UK.
·      Pridgeon, A.M.; Cribb, P.J.; Chase, M.W. & Rasmussen, F.N. (1999): Genera Orchidacearum (Vol.1). Oxford University Press, Oxford, UK. Schoser, Gustav (1993): Orchid Growing Basics. Sterling Publishing Co. Inc., New York City, New York, USA.
·      White, Judy (1996): Taylor's Guide to Orchids. Houghton-Mifflin, New York City, New York, USA.

No comments :

Post a Comment

Note: Only a member of this blog may post a comment.