430 



Bulletin 279. 



Fig. 121. Variation in height and 

 » stooling power. 



This is not due entirely to the 

 inherent tendency of the plant to 

 remain in bloom for a long or a 

 short period, but is influenced to 

 some extent by climatic conditions. 

 For example, since the plants bloom 

 only when conditions of tempera- 

 ture and humidity are favorable, a 

 few cold, wet days following the 

 beginning of bloom would delay the 

 appearance of the remainder of the 

 flowers, thus materially lengthening 

 the blooming period. 



Variation in longevity. — Plants 

 ••• ave been observed which behaved 



as annuals; i.e., after producing seed at the end of the first season they 

 died from no apparent external cause. Others survived for only two 

 or three years. On the plats which have been preserved, a large per- 

 centage of the plants, which are now nearly 6 years old, are still in 

 existence and appear to be as large and vigorous as ever. 



Variation in vigor. — Plants may be found which show a decided lack 

 of vigor. These plants often succumb to the influences of unfavorable 

 environmental conditions, though it does not necessarily follow that 

 low vigor is always associated with 

 lack of hardiness 



Variation in stooling power. — Some 

 plants send up but very few culms 

 while others produce a large number, 

 as many as 280 having been counted 

 on a single plant. To what extent this 

 is associated with vigor is difficult to 

 determine, but it is plainly evident 

 from an inspection of a large number 

 of vigorous plants that there is a 

 marked difference in the inherent tend- 

 ency of the plants to produce culms. 



Variation in disease resistance. — The 

 severe attacks of a "rust" (Puccinia 

 graminis) during the past two seasons 

 have afforded an opportunity to ob- ^^^ ^^^ Variation in yield of 

 serve the relative resistance of the hay from individual plants. 



