Why do laurel and holly trees have shiny waxy leaves?

Laurel and holly trees have developed special kinds of leaves to seal the water inside them during the winter months. Both trees are evergreen. Instead of dropping all their leaves in autumn, they shed old ones and grow new ones throughout the year. In winter the soil is too cold for the trees to draw water from it through their roots. Normal leaves would continue to transpire and give off moisture until the trees died of drought. But the special leaves of the holly and laurel hold the water. Their waxy surface and leathery texture make certain that the water is contained safely within the green tissues.(Qs and As)