Re: Why do watermelons have both black and white seeds?

Hi Heather

There is a difference between the white and black seeds found in a 
watermelon.  The black seeds are those that developed into seeds that would 
produce a plant if planted in the ground.  Don't worry if you swallow one 
of these because it will not grow in your stomach (no matter what your 
brother tells you).  The white seeds are those that will not grow if 
planted.  

This is a web page that might be of interest to you.  It is all about 
watermelons.

Watermelon Information