Oct., 1923] 



STOUT 



STUDIES OF LYTHRUM SALICARIA 



445 



during the first 18 days of bloom. The plant was in bloom 55 days. The 

 results obtained for selfing are summarized in table 1 and are shown in more 

 detail in table 2, in which, to facilitate ready comparison, the data are 

 compiled for three periods. 



Table 2. Record for controlled pollinations of mid- styled plant no. 1 in summer of igig 



Of the 140 flowers hand-pollinated with pollen from short stamens, only 

 three produced pods yielding 1, 10, and 37 seeds respectively, but these 

 may have been due to chance pollination with pollen from the long stamens 

 at the time of their removal or with pollen of other flowers which were 

 enclosed in the same bag. The results indicate that the plant remained 

 decidedly if not completely self-incompatible to pollen of its own short 

 stamens throughout the entire period of bloom. 



When pollen of long stamens was used in hand-pollinations, the propor- 

 tion of pods produced increased as the season advanced, and during the 

 last 18 days of bloom there were but 9 failures out of 79 flowers pollinated. 

 The results show conclusively that the self-compatibility in this plant 

 involves fertilizations from the pollen of long stamens, and also that this 

 compatibility actually increases toward the end of the period of bloom. 

 The increase in compatibility affects, however, the number of pods that are 

 formed rather than the number of seeds in a pod. The average number of 

 seeds in the pods that were produced was almost the same for all periods, 

 but the highest number of seeds in any pod was obtained during the first 

 iH days of bloom. 



The 22 legitimate cros>e> made (hiring the first 18 days gave 20 pods 

 with seeds ran^in^ in number from 12 to 176, with an average of 98 seeds 

 per capsule. These results show conclusively, as do those of open cross- 

 pollinations during the early part of the period of bloom in the previous 

 year, that the pistils of the plant are highly potent during the period of 

 marked self-incompatibility. The decided change in fruit-production is 



