Q.Why Do My Mexican Sunflower Leaves Look Different From Each Other
Only reason could be that I bought a pack of seeds and used some from last year. I have just never seen the leaves look like that before. (The left plant in the pictures)
Certified GKH Gardening Expert
It is likely that hybridization has occurred from nearby plants, or past genetics are showing themselves. This is not harmful, but will lead to some interesting flowers over time. Eventually, over years, they may all solidify into a single set of genetics.
This article will offer some information on their care: