There is very little vegetation that a hungry rabbit in the wild will not at least sample, especially when drought or cold has made food scarce. They'll eat just about any vegetable or grass they can find, various leaves, and flowers, and have even been known to strip the bark from certain trees. However, there are many plants that a rabbit will only eat as a last resort, when hungry enough.
Woodier, more difficult to digest plants are less likely to be eaten, and there is a long list of trees and vines that seldom see damage from hungry rabbits. There are also several plants that may even be poisonous and so rabbits know to avoid them. Here are some of the more common plants that seldom see damage by rabbits: Azaleas, Begonia Cacti, Columbine, Daffodils, Daylily, Four-O'Clock, Geraniums, Hyacinth, Lambs Ear, Marigold, Onion, Potato Rhododendron, Sage, Salvia, Sedum, Spider Flower, Spirea, and Yucca.