Scientific explanation - Compass plants
These compass plants avoid overheating by positioning their leaves in a north-south direction. As a result, the intense light of the midday sun only strikes the edges of the leaves.
The leaf surfaces are only in direct sunlight in the morning and afternoon. Having their leaves in this position also protects the plant from excessive water loss.
We call this type of plant "phototropic". They are found in sunny and dry regions. Often along the side of the road.