Ahhh, another new word to help me see the form - Helix meaning "spiral curve" like the recurving that shows up in your other Helix pictures in the database. I am learning that cooler weather means less curling on a bloom, and warmer weather encourages more curling. It's great to see what a name can tell us about the flower, and what pictures from different conditions can show us about how the blossom responds to it's environment!
