Unexplainable.
Here's two jovibara grouping in the same garden area; one bunch is in a flat that sits in morning sun and the other jovibara group sits in the semp bed in the late morning-afternoon sun with covering on real sunny hot days. Notice how wide open first grp is while the second grp that's been in noon sun is closed up and lighter in green color.
I purchased them at same time.
morning sun
afternoon sun
morning sun 
afternoon sun
