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Chlorophyll: Why Plants Always Wear Green

Donning the green is a St. Patrick's Day tradition, but plants wear green throughout the year. This green color is what makes plants a unique life form.

Chinese EvergreenChinese Evergreen
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Plants get their green from a pigment called chlorophyll which absorbs red and blue wavelengths of light and reflects green wavelengths. All green plants produce some of their own food supplies through a process called photosynthesis, which can only take place when chlorophyll is present. Thus, the very life of a green plant is dependent upon chlorophyll.

Light is also essential for photosynthesis to take place. The plant uses light and chlorophyll to manufacture carbohydrates from carbon dioxide and water in the plant environment. The leaves produce most of the carbohydrates, but stems and buds are also contributors.

Chlorophyll is only able to use a portion of the light that reaches it. On a sunny day, only about one percent of the light received by the plant will be used in photosynthesis. The rest will be reflected, transformed into heat, or used for other plant processes. Photosynthetic production will be dramatically cut back during cloudy weather or other low-light situations.

Not all plants will need maximum light intensity for good plant growth. Some species of plants require only one-tenth of full sunlight. This is the reason some plants, such as impatiens, are called shade plants and others, such as petunias, are called sun plants.

Houseplants also require varying amounts of sunlight. Because light levels inside the home are generally quite low compared to outdoors, we often think of houseplants in terms of their ability to adapt to low light. Most houseplants will grow best in as much light as you can supply in the typical home, but a few plants, such as pothos, snake plants, dracaenas and Chinese evergreens, can adapt to relatively dark conditions. However, these plants do need some light in order to survive. If the light is not bright enough to read by, consider artificial light.

--from Plants and Pests, Purdue University 
This page is updated monthly.
Revised:  March 05, 2018