Forest Vines to Snow Tussocks: The Story of New Zealand Plants
The leaves of plants of moist tropical forests are evergreen, generally larger than those of temperate forests and are often leathery and smooth-margined. Average leaf size decreases with increasing height above the ground and some of the trees have distinct juvenile forms with leaves much larger and/or more compound than those of the adults. In some cases there are narrow prolongations from the ends of the leaves known as 'drip tips', thought by some to enable rapid drying of leaves after rain.
Pulvini or elastic swellings at one or both ends of the leaf stalk or petiole are a common feature of tropical forest plants. It has been suggested that bending movements at these pulvini enable the leaf to maintain the best orientation to the light.