Heliotropic

I bought this plant last summer and forgot to keep the label telling me what it is. However, my very handy plant identifier app tells me it is a sowthistle - I remember buying various wildflowers at the time, including Jacob’s Ladder and cornflowers.
Now that it’s put out some flowers, I can see that it’s a heliotrope - the petals close up at night and open in the morning, to follow the sun during the day.