Answer: The term for having fold lines on the corolla (the collective term for all the petals) of a plant is "plicate."
Explanation: The term "plicate" describes the state in which the petals or other floral structures have been folded, pleated, or wrinkled. Numerous plant species, particularly flowers with many petals, have this folding pattern. The corolla is given a distinct texture or pattern by the fold lines, which gives the flower's look more visual complexity and intrigue.