Why does Charlemagne thistle report rain or shine?

Charlemagne thistle is native to Italy, and its Latin name is Carlin aacaulis. This is the name of the great herb, which comes from its long history. The second half of the name means "stemless". Is Charlemagne thistle really stemless? No, it has stems, but it grows underground. Its leaves are very long and have thorns on them. It looks like a lotus base. In flowering season, a large scape protrudes from the leaves, and a large flower grows at the top of the scape. The most wonderful thing is that this flower is an accurate "weatherman". It will tell people whether the weather is sunny or rainy.

When the weather is sunny, the big flowers stretch out and expose disc-shaped inflorescences. Seems to be basking in the sun. When dark clouds appeared in the air and it was about to rain, many bracts outside Charlie Mann's thistle chrysanthemum sequence automatically moved up and in, and slowly closed tightly together. A big flower in full bloom becomes a "bud" to be put. After the weather cleared, Charlemagne thistle began to unfold again. It is Charlie thistle, which is extremely sensitive to air humidity, that makes it an assistant for people to observe the weather.