VOLUME LX\III NUMBER 5 



THE 



Botanical Gazette 



NOVEMBER igig 



CHEMICAL constituents OF AMARANTHUS 



RETROFLEXUS 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 254 



M. L. Woo 



(with eleven figures) 



Introduction 



It is a well known fact that weeds retard the development of 

 cultural plants. This is due to a number of causes: use of water, 

 shading, use of nutrient salts, etc. It has been claimed for various 

 species of Amaranthus that they not only absorb nitrates to care for 

 their nutrient needs, but that they store much nitrogen as nitrate. 

 If this be true, this genus has an excellent adaptation to enable it 

 to combat cultural plants, for nitrate supply is a common limiting 

 factor for crop growth. In order to investigate this statement, to 

 locate the place of nitrate storage, and to determine the amount 

 of nitrogen used otherwise by this plant, separate analyses were 

 made of roots, stems, leaves, and branches of Amaranthus retro- 

 flexiis at various stages and under various conditions of growth. 

 The amount of the several carbohydrates was also determined in 

 each analysis, in order to calculate the carbohydrate-nitrogen ratio 

 which is lately receiving so much attention. A tissue analysis of 

 the seeds was also made in an endeavor to ascertain more fully the 

 chemical constituency of this plant, with the hope of learning 

 more of the peculiar germinative behavior of these seeds. 



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