Closed Gentian is an incredibly interesting plant. In the world of flowers where getting pollinated is the name of the game, this one plays hard to get. I have stood and watched a bumblebee use his front legs to force his way into these tight blossoms. It's a mighty struggle with the bumblebee pushing the petals aside with his feet so he can squeeze in to get the pollen inside. The bee remains inside for some time with much wriggling and buzzing and then with some difficulty, he backs out. One can only imagine what seduction technique the closed gentian has that makes the bumblebee willing to work so hard to get in there.
The white variety blooms a bit sooner. At least one bumblebee has visited some of these blossoms. You can see what the blossoms look like after the bumblebee has forced his way in, and then backed out. I'm nearly as fascinated with the closed gentian as the bumblebees are.