I remember telling my mom when I was a kid that I didn't like Romaine
because it was bitter. She told me that it wasn't. We only ever bought
Iceberg at home and I grew leaf lettuce. I'd had Romaine in a restaurant.
But after that, the restaurant salads were not bitter so I though maybe it
was something else causing the bitterness. Until now.

I've been getting boxes of organic produce from Full Circle Farms. The
Romaine we had tonight and last night was fine but the stuff in the two
shipments prior was so bitter that I didn't want to eat it. Only difference
I could see was that the bitter stuff was in bigger/'longer heads. So...

Does anyone know what causes the bitterness?