Some Adaptational Mechanisms of Orchids
L.C. De
ICAR-NRC for Orchids, Pakyong, Sikkim (737 106), India
DOI: NIL
Keywords: Adaptations, Crassulacean acid metabolism, Pseudobulb, Velamen
Abstract
Orchidaceae belongs to the 84 families of vascular plants that cover species following the epiphytic life pattern. Orchids have specific adaptational mechanisms in the roots, stems, leaves, flowers, seed and other physiological processes. Under water scarcity, these orchids have developed pseudobulbs, a energy, water, and nutrient storage bulb for adaptations. A wax coating covering the surface of the leaf, also prevents evaporation and gas exchange in drier or hotter climate. Epiphytic orchids have adequate root systems to enable them to grow in a poor nutrient environment when they grow at slow rate. In such cases, velamen of orchids helps to absorb water and also help to absorb nutrients from rainfall. Orchid seeds do not have endosperm and require a fungal association with mycorrhiza to provide its energy till the development of roots and leaves. This symbiotic feature is another adaption to make the orchid seed to travel longer and further distances for survival. In comparison to the activity of C3 photosynthesis, crassulacean acid metabolism (CAM) in many epiphytes plays a vital role in improving carbon gains and water use.
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