Several years ago we planted a few yucca plants near the fence below our house. The sharp, sturdy thorns at the end of the large leathery leaves make it less appealing for people to jump over the fence and cut through our property to get to the river. The plants have grown and do a good job of keeping people out in this area. For the first time these plants are putting up flower stocks. I'm not sure how tall the stocks will get, but so far they are about five-six feet tall. The stalks look like huge asparagus. I looked the plant up on Wikipedia and they actually do belong to the same family as asparagus.