54 



GRASSES OF IOWA. 



Hays and Boss* state that the flowers of wheat open at 40 

 minutes past 4 and closed at 18 minutes past 5 a. m., in Minne- 

 sota. Flowers of oats and timothy open between 7 an a. m. 



Pig. 44. Pollination of tall meadow oat grass ^Airlienatherum avenaceum.) 1, 

 Stamens before pollen is discharged; 2, Pollen discharged from anther; 3, Pollen dis- 

 charged; 4, Pollen in the act of discharging. (After Kerner von Marilaun.) 



Agrostis, 11 A. M. ; Elymus, between 

 12 and 1 p. m. Agropyron at 4; Holcus 

 opens its flowers twice during the day, 

 at 8 A. M. and at 7 p. m., provided 

 atmospheric conditions are favorable; 

 when the temperature is not below 

 57^ Fahrenheit. 



Beal says, in regard to the -length 

 of time a grass remains in flower: 

 " As a rule, a certain specified flower 

 of a grass remains open only for a 

 short time, but different flowers of a 

 plant may appear at successive 

 periods extending over eight days, 



breeding, cultivation. Bull. Univ. of Minn. Agrl. Exp. Sta. 



Fig. 44 B. Flower of wheat 

 with stameiiS and pistil. (After 

 Sauders.) 



♦Wheat varieties 

 62: 415. 



