148 THE SMALL GRAINS 



rye. The ancestral species is perennial and has an articu- 

 lated rachis which breaks apart at ripening, both of 

 which characters have disappeared. However, culti- 

 vated rye left standing a long time in the field will shoot 

 up again. 



137. Roots. Germination of rye is more rapid, and 

 may take place at a somewhat lower temperature, than in 

 the other cereals, and therefore rye usually comes up 

 quickly after being sown. The coronal root system is 

 composed of a number of so-called adventitious roots 

 which are sent out at the base of the culm or crown, 

 which is usually less than one inch under the surface of 

 the ground. No tap root is formed. The adventitious 

 roots are slender, fibrous, and grow downward more or 

 less directly into the soil, the system being vertical rather 

 than lateral. By branching they form a network which 

 occupies the soil more or less completely. Rotmistrov 

 (1913, p. 24) found that the roots of winter rye, at the 

 milk stage of the kernel, extended downward 130 cm., and 

 the lateral spread was 92 cm., making the root coefficient 

 7080. 



138. Culms. The height of the rye plant depends 

 upon the circumstances of the environment. Under the 

 best conditions it may sometimes attain a height of 10 

 feet, and frequently a height of 7 feet. The average, 

 however, is not over 5 feet, it being usually 6 to 12 inches 

 higher than wheat grown under the same conditions. 

 The culm is cylindrical and the surface smooth, except 

 near the top, where it is rough and thickly covered with 

 short hairs. The diameter of the culm is less than that 

 of the other small grains, and this with its greater height 

 makes the rye culm appear rather delicate and weak, but 

 in reality it is tough and rigid and does not lodge on 



