Plants have evolved all sorts of wickedly clever defense mechanisms, and the most primal—and effective—are thorns, prickles, and spines. Spiny plants can be a hassle when it comes to maintenance and pruning, but when it comes to your personal home security, these masters of pain kick serious butt defending property lines and first-floor windows.

As a bonus, most of the plants trick themselves out with delicate blossoms in spring and colorful berries in fall. They're tough and hardy across many growing zones, and those that are shrub-like can be pruned into impenetrable hedges. This helps keep any home from looking like a max security complex.

If you have kids or animals, these may not be the plants for you. But for many, it's a more elegant solution than an unsightly barbed wire fence.