A few comments about the Hedge of Buckland: "Their land was originally unprotected from the East; but on that side they had built a hedge... now thick and tall... But ... it was not a complete protection". During the discussion of the black riders, it sounds as if the hedge is a protection from them, since it is assumed that they could be stopped at the North-gate (implying that they could not pass through the hedge at other locations). When Frodo and company leave Crickhollow and first encounter the Hedge, it seems impossible to get through it, but Merry says "follow me, and you will see". The gate is in a cutting under the Hedge, with a locked gate with thick iron bars". All this makes it seem to me that the Hedge is more than just a screen to keep the Old Forest out of sight, which is what Corey seemed to imply in his remarks. It sounds like a formidable barrier, even if it is not a complete protection. Note also that the major defense of Bree also depends on a hedge, "a deep dike with a thick hedge on the inner side". Where the road pierces the hedge, it is barred by a great gates, with lodges for the gatekeepers. It rather sounds like this hedge is also formidable barrier. When the hobbits enter Bree, Strider sees them and follows over the gate rather than attempting to pass through some other location in the hedge. It rather seems that hedges are considered a significant protection, not just by hobbits, but also by the men of Breeland. When I took a field botany class years ago, the instructor taught us that a good pyracantha hedge would be impenetrable. I've seen them and believe it's true.