between yields of the latter two groups. Lowered seed 

 yields accompanying self-pollination in western white 

 pine is well documented (Bingham and Squill ace 1955; 

 Squill ace and Bingham 195 8; Barnes , Bingham and Squill ace 

 1962) . 



As noted previously (Bingham and Squillace 1955), 

 the yield of total seeds (filled plus hollow) was essen- 

 tially the same regardless of the type of pollination 

 (table 7) . The large proportion of hollow seeds that 

 develop after self-pollination apparently result from 

 embryo abortion because full -si zed hollow seeds failed to 

 develop following earlier failures in pollination, pollen 

 tube growth, or fertilization in Pinus sylvestris L. 

 (Sarvas 1962) . 



Table 1 .--Yield of filled and hollow seeds per cone from 

 wind-, cross -, and self-pollinations . Compari- 

 sons are based on yields from trees on which 

 observations were available in the same seed 

 years 



Comparisons Yield of seeds per cone 



Pollen 



Years 



Group 



observed 



observed 



type 



Filled 



Hollow 



Total 



A 



28 



9 



Wind 



111 



.2 



12 



.0 



123. 2 









Cross 



102 



.7 



21 



.4 



124.1 









Self 



60 



.9 



57 



.4 



118.3 



B 



40 



11 



Wind 



102 



.1 



13. 



.7 



115 .8 









Cross 



94 



.4 



21 



.3 



115.7 









Self 













C 



141 



12 



Wind 



















Cross 



95 



.4 



22 



.9 



118.3 









Self 



51 



.8 



58 



.6 



110.4 



L0 



