Ontogenetic Variation in Leaf Morphology of Ginkgo biloba L.: Age-Related Differences in Seedlings

This study examined age-related variation in leaf morphology and plasticity in 2-, 3-, and 4-year-old Ginkgo biloba seedlings grown under uniform conditions. The measured parameters included leaf width, right and left lobe lengths, middle lobe length, sinus depth, petiole length, leaf area, area-to-width ratio, area-to-lobe ratio, specific leaf area, and selected proportional indices. Results showed that leaf area, leaf width, right and left lobe lengths, middle lobe length, sinus depth, petiole length, area-to-width ratio, and area-to-lobe ratio reached maximum values at age 3, indicating a peak in lamina expansion and lobe development. In contrast, specific leaf area was highest at age 2, suggesting thinner leaves with lower structural investment during early ontogeny. Principal component analysis clearly separated age classes, mainly along a size-related axis dominated by leaf area and lobe traits. While absolute size parameters changed significantly with age, several proportional traits remained stable, indicating conservation of structural relationships. Plasticity indices were generally highest at age 3, reflecting increased developmental flexibility before partial stabilization at age four. Overall, the results demonstrate clear age-related changes in leaf morphology, with the third year representing the stage of maximum morphological expression in Ginkgo biloba seedlings.