Illustration of etiolation phenomenon
Etiolation response is one example of how a plant's morphology and physiology are tuned to its variable surroundings by complex interactions between environmental and internal signals.
Consider a forgotten potato in the back corner of a kitchen cupboard.
This potato (modified underground stem, or tuber) has sprouted shoots from its "eyes" (auxillary buds). These shoots, however, scarcely resemble those of a typical plant. Instead of broad green leaves and sturdy stems, these plants are ghostly pale, bear leaves that are unexpanded, and lack elongated roots in darkness, collectively referred to as etiolation.
Under these circumstances, expanded leaves would be a hindrance to soil penetration and would be damaged as the shoots pushed through the soil. Because the leaves are unexpanded and underground, there is little evaporative loss of water and little requirement for an extensive root system to replace the water lost by transpiration. Moreover, the energy expended in producing green chlorophyll would be wasted because there is no light for photosynthesis. Instead, a potato plant growing in dark allocates as much energy as possible to the elongation of stems. This adaptation enables the shoots to break ground before the nutrient reserves in the tuber are exhausted.
Importance of Etiolation Phenomenon : The etiolation response is one example of how a plant's morphology and physiology are tuned to its variable surroundings by complex interactions between environmental and internal signals.