Ask Mr. Smarty Plants

What you want is something thick and stickery, right? Well, we know a native plant, Mahonia trifoliolata (agarita) that also has the common name "baby-sitter plant" because it is sometimes used in the Southwest to protect lambs from the circling coyotes. It shelters and feeds birds, is evergreen and attractive. The bad news is, it is native only to New Mexico, Texas and Arizona. Randolph and Delaware Counties, Indiana are apparently in USDA Hardiness Zones 5a (average minimum temperature -20 to -15 deg. F) to 5b (average minimum temperature -5 to -10 deg. F). Agarita is hardy to +15 deg. F. Scratch that idea.

We actually don't feel you are going to find a plant that will give you year-round confinement of your sheep and protection from predators. To begin with, whatever you plant is going to take several years to get to a height that will be reasonable for protection. Plus, a sheep anxious enough to go roaming or a predator hungry enough to have a bite of lamb could almost undoubtedly find a way to get through just about any shrub foliage that you had in place. 

You already know more about sheep fencing than we do, but here is a website from Sheep 201 on Fencing. We looked at our Native Plant Database to see if there might possibly be an Indiana native shrub that would work, but the closest we could come was Juniperus communis var. depressa (common juniper). Both its cones and leaves are toxic, which would pretty well eliminate that as a livestock fence.  We hate to say so, but sometimes native plants are NOT the solution.