LINUM USITATISSIMUM 



377 



along the upper 8 cm. of the primary root. When the cotyledons 

 are liberated from the seed coats, they separate and expand for 

 several days prior to the elongation of the epicotyl, which differ- 

 entiates very slowly at first, appearing as a compact bud with 

 several small leaves at the end of ii to 15 days. 



After the seedlings are about an inch above the ground, they 

 grow slowly for two or three weeks and then there is rapid increase 



O 



01 



Fig. 191. The seed and stages in development of seedling. 



in height which continues until the time of blossoming if condi- 

 tions are favorable. The first internode always remains short, 

 not exceeding i mm. in length at maturity, the second internode 

 is longer than the others, attaining a length of about 15 mm., 

 and the remaining ones vary from 5 to 10 mm. 



ANATOMY 



Anatomy of the Seed. — The mature seed coat consists of 

 several distinct layers. The outer one is made up of cells which 

 are polygonal in surface view and rectangular in longisection. 



