A week or so after I took the picture for Alone and Perfect, I took this one. This magnificent flower appears to close up at night. While probably not the same exact flower, it was close enough, and now looks somewhat forlorn. I remembered the word “heliotropic” from high school, but this probably wasn’t the same process as following the sun. But the more I tried to remember, the more I seemed to recall that that’s exactly what we were taught. I could swear the teacher explained to us that sunlight holds the flower open using the same mechanism as heliotropism. Alas, Elizabeth Palermo, Associate Editor of LiveScience says the process is called “nyctinasty”, explaining that “In cool air and darkness, the bottom-most petals of certain flowers grow at a faster rate than the upper-most petals, forcing the flowers shut.” She also offers the opinion that such flowers are more highly evolved than those that do not close, citing Charles Darwin and others. So, I've remembered the word “heliotropic” for more than fifty years but have to sound out “nyctinasty”, which I won't remember five minutes from now. Either they didn’t understand this when I was in high school or else someone’s making things up. Either the flowers grow shut or else the process that holds them open loses its force. I think I prefer the incorrect answer.