A quick google search for "edible tree leaves" yielded quite a number of ideas so I think that in general the answer is yes. I don't think maple leaves are particularly edible, but the paper birch Betula Papyrifera is edible. All parts, including leaves. Also, our page on orangutans indicates they eat 400 different types of food in the rainforest, much of it bark and leaves. Orangutans are relatively similar to humans, so there are likely quite a number of leaves of tropical trees and vines that we can eat. In addition there are many shrubs and bushes that have edible leaves. For instance, tea leaves and grape leaves. And of course, don't forget the coca bush whose leaves are chewed for the cocaine. The Linden tree, tilia genus, certainly has edible leaves and flowers. The leaf buds and young leaves can be eaten raw. The Wikipedia has a big long list of plants with edible leaves. These are all the Latin names, but you can look these up on Google, or at the library and learn all about these plants if you wish.