Materials scientists engaging in biomimicry of plant surfaces classify three levels of wettability of plants. It turns out that the least wettable leaves, or superhydrophobic leaves, often use both epicuticular wax and surface structure to avoid absorbing water. This phenomenon is sometimes called the lotus effect:
This can keep the plant from getting weighed down, can direct water down the stem or away from it, and can also repel other things that may damage the plant.
Here's a paint that uses the same technique to repel water:
Image: YouTube / Da Vinci TV