If you find that article, I'd love to see it. I know a bit about plant hormones, but most of what I remember is some of the growth hormones degrade in sunlight

If you find that article, I'd love to see it. I know a bit about plant hormones, but most of what I remember is some of the growth hormones degrade in sunlight, which can cause the apparent growth toward the sun. So if you have a stem and the light is coming from the right, the cells on the right side don't divide or elongate as quickly as the cells on the left side in the shade, which causes the stem to bend to the right. This is also the cause of etiolation, or legginess, in plants that aren't getting enough sun. Those cells have plenty of the hormone as it's not being degraded by the sunlight, causing them to elongate more quickly than a plant getting adequate light.