248 



COLORATION IN ORNAMENTAL FOLIAGE PLANTS^ 



In a walk through the greenhouses and about the grounds 

 of The New York Botanical Garden one sees many different 

 kinds of plants having gayly colored leaves. The range of colors, 

 the di\ersity of their combinations, and their arrangement in 

 patterns make these plants especially attractive and valuable 

 as ornamentals. 



In regard to the kinds of coloration we may group plants with 

 colored foliage into two main classes: — in one there is a loss, 

 or change, or substitution in the green coloration so that portions 

 of the lea\es or even entire leaves are white or of some shade of 

 yellow; in the other there is some shade or grade of red or blue 

 coloring material. Both these kinds of coloration may be present 

 in the same leaf but they are quite distinct in nature and in 

 origin. In fact, the chemist finds that yellow pigments and also 

 certain red pigments which give quite the same appearance to 

 leaves may be very different in composition. 



The normal color of the leaves of the greater number of the 

 higher forms of plant life is green. This is due to the presence 

 of a coloring material or pigment technically called chlorophyll — 

 a word that means leaf-green. For the proper development of 

 this pigment light is necessary and certain food materials such 

 as iron salts must be available to the plants. Also, certain 

 internal structures of the jjlant or, we may say, of the cell 

 mechanism must be present and in ])n)per working order. Loss 

 of green may, therefore, be due either to external or to internal 

 conditions. 



The green pigment in plants performs a very vital function 

 in the work of making food. It absorbs certain wave lengths of 

 sunlight and this supplies energy to the liAing cells for the making 

 of simjile sugars — the first step in the building of all plant and 

 animal foods. Thus, in general, the presence of green indicates 

 that a plant can make its own food. Tlic absence of green in 

 plants which are usually green very often indicates an unhealthy 

 condition. 



As to the intensity of the loss of green, there may be partial 

 loss giving some shade of yellowish green or there may be coni- 



• Abstract of lecture given in the Central Display House, Conservatory 

 Range 2, 011 Saturday afternoon, March i, 1924. 



