636 



Journal of Agricultural Research 



Vol. XII, No. 10 



centage, in one instance produced as low as 31.7 per cent of abortive 

 grains. Numerous other equally striking variations in pollen abortion 

 will be evident by referring to the table. 



In view of the variability shown above, the pollen condition was deter- 

 mined in all of the flowers from two inflorescences of Minnesota 3 

 to determine what variations occur in flowers grown under so nearly 

 similar conditions. The results of these counts are presented in Table 

 VIII and exhibit as great variability within the flowers of a cluster as 

 is found between flowers from separate plants. In one stalk the range 

 is from 31.2 to 91. i per cent, in the other it is from 21.4 to 40.3 per cent, 

 while the range in other counts of the same variety (Table VII) from 

 different plants is from 14.2 to 60.4 per cent. 



Table VIII. — Percentage of aborted pollen in all of the flowers from two stalks of 



Minnesota j 



o Anthers intermediate. 



In view of the variability shown between different plants of the same 

 variety and between different flowers of a single inflorescence, a study 

 was made of the variation in pollen conditions of individual anthers 

 within a single flower. The pollen of nine anthers, from a flower of 

 Seedling 778 was studied, four of which were from the outer para- 

 petalous series, three from the middle antipetalous series, and two from 

 the inner long filamented antisepalous series. The results, given in 

 Table IX, show a greater range of variability between the anthers of a 

 single flower than was exhibited by the five separate flowers of the same 

 variety reported in Table VII. Because of the extremely great varia- 

 bility in pollen condition shown by some varieties, as Abington, Abun- 

 dance, Aroma, Darlington and others, which often produce nearly perfect 

 pollen (as far as can be determined by this method of study), while at 

 other times, apparently under the same conditions, high percentages of 

 abortive pollen are produced, too much stress should not be laid on a 

 few scattered observations in determining whether a species is pure or 

 of hybrid origin until more is known of the factors which produce such 

 great variability. It may, of course, be argued, and logically, that a 

 large number of the grains in the anthers, which produce nearly perfect 

 pollen, are truly abortive, but have developed beyond the stage where 



