How does a common leaf grow, say maybe a rose leaf?

Question

When a leaf grows from a small leaf to a large leaf, does the growth (addition of new cellular material) take place at the margins(edges) or near the veins?

If it takes place at the veins, which is where the most undifferentiated cells exist, why does the margins of the leaf not crack from stretching?

Answer 1

photosynthesis??????

thats a guess ^^