A. Crispus propagation

This is a follow-up to my question about an A. crispus in my tank which 
is putting out flower spikes but not producing seeds.  Thanks for all the 
replies.  One suggestion was that I am removing the spike too early, and 
that the seeds will develop if I let it start to decompose on the plant.  
I am trying this now, but it doesn't look to me like much development is 
taking place.  Certainly not on the time scale of the growth of the spike 
from base to top of the tank.

Another suggestion, from Karen Randall, was that the plant may not be 
self-fertile.  I have two of these, but only one has generated a spikes.  
The first A. crispus began putting up spikes shortly after the first 
leaves reached the surface.  The second one just has not developed to the 
same degree as #1.  It may be getting out-competed and is probably 
planted too close, about 2" separation.  If #2 starts to develop flower 
spikes, will the two plants pollinate one another?  It seems that this 
would be beneficial in any case.  Should I do anything to help the 
pollination, when I do get flower spikes from #2?

Thanks in advance for any advice.