PLANT GROWTH AT DIFFERENT STAGES 251 



Flower head Early Full End of 



invisible. bloom. bloom. flowering. Ripe. 

 Percent. Percent. Percent. Percent. Percent. 



Dry matter 9 31 97 100 97 



Total ash 14 46 98 100 95 



Total nitrogen 15 37 100 96 94 



Proteid nitrogen ..... 67 70 88 85 83 



Fiber 5 24 92 96 100 



Potassium oxid 15 50 100 94 86 



Calcium oxid 15 37 97 100 97 



Magnesium oxid 8 35 100 92 91 



Phosphoric anhydrid. 14 34 98 100 98 

 (These tables are from Minn. Expt. Sta. Bull. 34.) 



352. Flax; Rapidity of Growth. The flax plant has a 

 short growingperiod, about seventy days, and the plant food 

 is assimilated at a rapid rate. Before the time of bloom, 

 the nitrogenous material and mineral matters have been 

 absorbed in quite large amounts. When 40 per cent, of 

 the nitrogenous matter has been produced, the flax plant 

 contains 55 and 60 per cent. , respectively, of its total 

 nitrogen and mineral matter. At the time the flax is in 

 full bloom, 75 per cent, of the organic compounds have 

 been formed. After seed formation begins, there is no 

 nitrogen or mineral matter taken from the soil. Flax is 

 very rich in nitrogen, containing even more than clover. 

 This is one of the few crops in which the ash in the seed 

 exceeds that in the straw; the seed contains about 3.75 

 per cent, ash, while the straw contains less than 3 per 

 cent. The oil in the seed is produced mainly from starch 

 in the later stages of growth. Between full bloom and 

 maturity, less than 25 per cent, organic matter is pro- 

 duced. The rate of formation of the organic matter and 



