Mar. II, 1918 



Sterility in the Strawberry 



625 



the later more sterile flowers were in blossom. Further, the fact that 

 pistillate varieties, grown in proximity to hermaphrodites, set fruit even 

 in the early part of the season, when pollen is admittedly scarce, would 

 argue for pollination having little to do with nubbin formation. To 

 those who have noticed the effect of frost on strawberry flowers it will 

 be clear that this factor may also be eliminated as a cause of irregularly 

 set fruit, as frost, if it injures the flower at all, will blacken the entire 

 receptacle. The possibilities of the primary flowers being "frostbitten" 

 are much greater than the later ones, but it is the latter which generally 

 form nubbins or are entirely sterile. 



Table III. — Relationship between flower position and number of fruits set in hermaphro- 

 ditic and pistillate varieties of strawberries 



Variety. 



Ses. 



Num- 

 ber of 

 stalks 



Primary. 



Set. 



Not 



set. 



Secondary. 



Set. 



Not 



set. 



Tertiary. 



Set. 



Not 

 set. 



Quater- 

 nary. 



Set. 



Not 

 set. 



Quinary. 



Set. 



Not 

 set. 



Reasoners 324. 

 Seedling 947... 



Orem 



Lovett 



Seedling 893.. . 

 Seedling 1023. . 



Abington 



Everbearing. . 

 Glen Mary . . . . 

 Seedling 924. . . 



Total . . . 

 Per cent . 



Paul Jones . 



Marie 



July 



Wildwood . 



Total . . . 

 Per cent . 



66 

 III 

 79 

 72 

 83 

 77 

 90 

 6j 

 74 



87 

 55 

 68 

 77 

 S8 

 90 

 82 

 107 



6 

 1-3 



68 s 

 65.8 



356 



34-2 



IS5 

 65-7 



5 

 83.3 



48 



286 

 90.8 



177 

 66.5 



80 

 47 I 



6 

 100 



Table IV shows the relation between flower position, imperfectly 

 developed fruit or nubbins, and complete pistil sterility. It corroborates 

 what has already been pointed out, namely, that the first flowers of an 

 inflorescence are much more fertile than the later ones. With regard 

 to nubbins the same relationship is shown — that is, there is a gradual 

 increase in the percentage of nubbins formed from the primary to the 

 last flowers which open. This condition can hardly be construed as 

 indicating anything but a morphological sterility of a portion of the 

 pistils in those flowers which result in nubbins, if viewed with the facts 

 in mind of the condition shown in the hermaphrodites of the wild parent 

 species, the unquestionable sterility of many of the later flowers, and the 

 fact that the greater percentage of these partially sterile flowers are in 

 bloom when pollen is most abundant. If it were a question of pollina- 

 tion, we would expect the pistillate forms to exhibit much more sterility 

 than the hermaphrodites, whereas they exhibit decidedly less, both with 

 regard to the actual number of sterile flowers as well as nubbins. 



