These Are 11 of the Prickliest Plants on the Planet

When you think of holly, you're certain to conjure images of the plant's evergreen leaves and red fruit, but do you consider its thorns? Each of the leathery leaves has three to five spines along its sides. They alternate in direction, with some spines pointing upward, and some downward. Meanwhile, the highest branches of mature holly trees completely lack the sharp appendages.

These spines actually explain the plant's connection to Christmas. Originally, in pre-Christian times, pagans used the plants to ward off evil spirits and to celebrate the Winter Solstice Festival. Over time, Christians added their own meanings to them. The leaves are meant to represent the crown of thorns that Jesus wore during crucifixion, and the berries represent his blood. In Scandinavia, holly is even referred to as Christ Thorn.

Agave is a genus of plants that includes many species of succulents that live in hot and arid conditions. These plants have adapted to their desert homes with various features, including spikes. In this case, the spines poke out at predators to deter them from using the leaves as a water source. The spikes are so strong and sharp, in fact, that ancient women in Mexico were known to use them as needles for sewing.

Acacia trees are often associated with Australia, which makes sense—it takes a tough tree to survive in a tough land. But it's also native to Africa, and rumor has it that in Egypt, the leaves were ground up and used to treat hemorrhoids. But it's the tree's limbs that hand out the most punishment. These barbarous branches are studded with curved prickles that excel at snagging and not letting go. However, there are other species of Acacia with a less-thorny personality.

Think of this plant like a no-nonsense rose: all canes and prickles, and no showy flowers. They're incredibly fast-growers and can quickly turn into a twisted biomass of hurt. They grow about five feet high, and this wall of pain can be as wide as you'd like. Because of their tendency to grow quickly, you'll need to be a diligent pruner, but hey, at least you get those berries.

A fast-growing shrubby vine that can grow 40 feet long, Bougainvillea uses its thorny stems to support itself on nearby plants or structures. The colorful display is actually made up of large, papery bracts that surround the tiny flowers, and you definitely don't want this plant's sap to touch your skin.

A great name for any death metal album, this climbing shrub grows three to five feet high and sends heavily armed branches in every direction. Originally from Madagascar, it usually needs support and looks for other plants or a fence to hold it up.

Crimson summer flowers are but a beautiful face in front of the insidious matrix of thorns beneath. Supposedly, a circle of Euphorbia was placed on Jesus' head to make the infamous "crown of thorns." And this plant is evil all the way through, as its sap will irritate the skin and can be toxic if ever ingested. (If you do ever eat this thorny nightmare, you might experience some other problems as well.)

Pyracantha is ready to go to battle with just about anything you could throw at it, which includes those pruning shears. It's armed with needle-sharp spikes every few inches along its stems and branches, and features tips with 4-inch-long hypodermics. Firethorn can grow 10 feet tall and nearly as wide. It's a hardy plant that endures plenty of abuse, and it can spread quickly. You'll need to be ready for battle if you hope to save your yard from this thorny beast.

Nobody's climbing this tree, which can grow 60 to 90 feet tall, because the rough bark of the honey locust is often covered with 6-inch dagger-like thorns—it's the Freddy Krueger of plants. Botanists say the thorns evolved to protect the tree from giant sloths and short-faced bears that roamed North America thousands of years ago. Although these pre-historical fauna are no longer around, the flora's deadly defenses still are.

Mahonia may have bright evergreen leaves, but don't let that cheery foliage catch you unaware. Each waxy leaf is rimmed with Lilliputian spines that easily penetrate clothing, including leather. The shrub produces dense foliage that can be shaped into a hedge, but at least its clusters of edible blue-black berries are a late-season treat.

It would be hard to find a more aggressive-looking combo of leaves and stems than Solanum, also known as devil's thorn—a hardy shrub that can grow five feet tall. Some species contain a toxic alkaloid that, if ingested, can cause serious sickness and even death. As if those spines weren't badass enough.

A rose by any other name would be just as ornery. Whatever type you grow—garden, climbing, ground cover—you'll get a beautiful flowering plant with unsurpassed irascibility. As you've likely experienced before, roses draw blood, and they enjoy it. Let them climb over fences, or add garden roses and ground cover to the sunny sides of your house.