Why are the edges of these leaves white?
The white color is called variegation. Some variegated leaves are caused by genetic mutation, while others are the result of a virus. Either way, they are cultivated for their different appearance. Recent studies have shown that plants with the mutation for variegated leaves have a distinct advantage when it comes to pests such as leaf miners. The white areas resemble the damage caused by leaf miners, so the actual pests bypass the plant and look for another host.