Painting on a leaf

Went for a walk at the Botanic Gardens last weekend and picked up a leaf from the ground to bring home. I did a small painting on it the next day, it looked great when I just finished, but it ‘shrink’ and wrinkle up the next day! I tried to press it down with my sketchbooks but it seems too late, does anyone know how to fix it??

painting on a leaf

painting on a leaf

Copyrighted Image (c) April Yip, Leafbear Studio