If you're lucky enough to have a garden, you'll know what it's like to battle weeds all year. However, some are worse than others.

These nine pernicious plants might look beautiful, but they can pose surprising risks, from crowding out native species to causing bodily harm like blisters, burns, or even death.

Click or scroll on to learn how to identify these unwanted plants and what to do if they appear on your property...

Best known for ending the life of the Greek philosopher Socrates, poison hemlock is found across the country. It thrives in damp places and can form vast colonies in creek beds and ditches and on waste ground, riverbanks and roadside verges.

Even a tiny amount of hemlock can cause muscular paralysis, which can lead to organ damage, respiratory failure and death in humans and other mammals.

You can tell hemlock apart from other plants thanks to its tall, hollow, purple-spotted stems, which reach up to 6.5 feet (2m) high and are topped with flat clusters of small white flowers.

Its fern-like leaves are more feathery than the similar-looking Queen Anne's lace and emit a foul smell when crushed.

To prevent your garden from becoming overrun by this killer plant, like this equestrian centre in California was, you can remove hemlock by (gloved) hand, pulling or hoeing it, or by applying herbicide to seedlings or young rosettes.

In 2021, a Madeira, Ohio man narrowly survived a near-fatal coma after he inhaled tiny particles of hemlock when cutting back honeysuckle with a chainsaw in his yard, according Local 12 WKRC. He spent 109 days in hospital. 

Thanks to its tufts of pink flowers and delicate fern-like leaves, it's easy to see why the mimosa tree was introduced to the US from Asia back in the 1700s as a pretty addition to any garden.

However, it has an ugly side. Its seeds contain a neurotoxin that is toxic to dogs. It's also a fast grower that pushes out native plants, impacting the local ecosystem.

These bright pink feathery flowers give the plant its other name, silk tree, and are a dead giveaway when it comes to identification. The fluffy blooms are nectar-rich, which prompts some people to plant the tree in a misguided attempt to attract hummingbirds.

The tree reaches only 15–25 feet (4.5–7.6m) high, but its low-branching crown can spread up to 35 feet (10.6m) across.

Repeatedly girdling or cutting the tree close to the ground before it produces seed pods, like these, has proven effective in controlling the spread of mimosa trees, according to the USDA. Using a herbicide after cutting can control resprouting.

Hand-pull seedlings, ensuring you remove the entire root. Regular mowing of seedlings up to 4 inches (10cm) tall can also control their spread.

Ivy-clad buildings may look rather grand, but behind that deep-green leafy facade, this aggressive plant can pose a threat. Introduced to the US from Europe in the 18th century, English ivy provides food and shelter for birds and insects, but it's a lightning-quick grower that can crowd out native plants.

Thanks to hairy aerial roots, this evergreen climber can cling to vertical structures and typically climbs up to 90 feet (27m), damaging trees, walls and buildings along the way. It can also pose a fire risk.

Juvenile English ivy has glossy three- to five-lobed leaves with pale veins. It's this young plant that typically forms ground cover and climbs up anything it can find.

Mature branches don't cling. Instead, they produce bushy diamond-shaped leaves, along with bursts of pale greenish yellow flowers (pictured) in the fall, followed by clusters of black berries in winter, which are harmful if eaten.

Ivy has been known to scramble to the top of 300-foot (90m) conifer trees, so it's a good idea to keep it in check. 

When removing it from a tree, cut each ivy stem at about chest height, then hand-strip the lower portions from the tree. Clear a 6.5-foot (2m) ring around the base of the tree. Don't attempt to pull the remaining ivy from the upper portions of the tree, as this can be a safety hazard.

You can unstick aerial roots from buildings and walls using pruners or a construction spatula. A claw hammer can also be handy for pulling up vines.

Also known as Bradford pear, Callery pear can produce dense thickets as it grows quickly in sunny conditions, matures early and produces seeds that are dispersed widely by birds. Hard to control, it's classed as invasive in Alabama, Delaware, Maryland, Missouri and North Carolina. 

Despite its pretty spring blossom, the "smelly flowers...reek like rotting fish", according to House Beautiful. Its weak wood splits easily in heavy snow or high winds.

If you live in the North East, South and Midwest, you'll likely spot Callery pear growing in number along roadsides, in old fields and hedgerows, and along forest edges.

These small trees rarely top 40 feet (12m). You can recognise them thanks to their thick, waxy leaves and the white flowers that appear in early spring. 

Flowers are followed by tiny round pears that grow in clusters. They're green-ish brown and flecked with pale spots.

While undoubtedly beautiful and popular with wildlife, Callery pear trees should ideally be cut down and treated with herbicide before being replaced with a native species. 

Saplings can be pulled up by hand, but, as with many invasive plants, root fragments can often resprout, so be thorough. 

You'll need to be vigilant if there's a seed source nearby, as Callery pear often reinvades areas it's been removed from.

This dense, round shrub may look pretty, but don't be fooled, it's an aggressive grower that can alter soil pH and shelter black-legged ticks, which carry Lyme disease.

Prohibited in New York, Japanese Barberry has become problematic in Alabama, Connecticut, Delaware, Maryland, Michigan, North Carolina and Wisconsin.

Japanese Barberry grows to 3–5 feet (1–1.5m) and spreads to about the same width. Sharply pointed spines run along its stems, hidden by the shrub's small green leaves. 

Clusters of yellow flowers appear in spring, followed by glossy red berries. Leaves turn dark red or orange in the fall.

Unless you want to risk dense thickets like these forming on your property, you'll need to control growth by pulling up or cutting young seedlings before their roots become well-established.

For mature plants, cut the shrub close to the base and immediately apply a herbicide to the stump. 

Replace the shrubs with native ones that support local wildlife and preserve a balanced ecosystem.

Tree of heaven arrived from China in the 1700s and now appears in more than 30 states. Despite its heavenly name, it's also known as stink tree and stinking sumac, thanks to the less-than-pleasant odour emitted by its leaves when crushed. 

It's classed as an undesirable due to its ability to grow up to 15 feet (4.5m) a year and to weaken surrounding plants by releasing harmful chemicals.

Poking through a pile of rubble, this small tree of heaven demonstrates how it really will grow anywhere. 

Large feathery leaves and rough, fissured bark are dead giveaways when trying to identify a tree of heaven. From late spring, pale yellow-green flowers appear, followed by pinkish winged seed pods (pictured).

Despite its ability to grow in poor soils with little water, tree of heaven can reach more than 39 feet (12m) in its lifetime. 

As with many of these pesky plants, you can pull seedlings out by hand, being sure to get the entire root system. The sap is a skin irritant, so wear gloves while handling. 

The most effective way to get rid of a mature tree is to use a hand axe to make cuts around the trunk at one level and then squirt tiny amounts of concentrated herbicide into each slash, according to Gardening Know How.

Chinese Wisteria in full bloom looks glorious. However, as we can see here, it has the ability to climb more than 39 feet (12m) and completely take over, given the right conditions. 

Their thick vines can strangle other plants, and damage or pull down the trees and structures they grow up.

One surprising way to distinguish Chinese wisteria from its cousin, Japanese wisteria, is to check the direction in which the vines wrap around things. If it's Chinese wisteria, it'll twine counter-clockwise, while Japanese wisteria goes clockwise, according to The Spruce.

The show-stopping flowers appear in dangling racemes of blue-purple blooms, which flower all at once. They're followed by long, fuzzy seed pods.

If you'd prefer not to use chemicals to remove your wisteria, you can cut the vine early in the growing season and continue to cut away any new shoots until the fall. The aim is to exhaust the plant, but you'll have to keep an eye on it to ensure it doesn't take hold again. It would be a good idea to remove the roots too, if you can. 

Spraying the leaves with a herbicide can be effective, although repeated applications are needed and it can damage nearby plants.

Also known as pale yellow iris or water flag, yellow flag iris is another surprisingly beautiful yet pernicious plant. Prohibited in Maryland, New York and Connecticut, it's a water-loving plant usually found in sunny spots on the edges of lakes, ponds and bogs.

While popular with bees thanks to its nectar and pollen-rich flowers, the yellow flag iris is toxic to cats, dogs and humans.

The yellow flag iris certainly lives up to its name. The three to four inch (8–10cm) flowers range from pale yellow to almost orange in colour and flutter above a 20–40 inch (50–100cm) stem with sword-shaped leaves.

Its thick underwater rhizomes (a type of root) emmit a black sap, which is toxic if swallowed and can also cause skin irritation.

Unless you want your pond completely overrun by an aggressive colony like this one, be sure to remove flowers as soon as the plant has bloomed so the seeds can't spread.

Dig up the plants and remove as much of the rhizome as possible, as new stems can sprout from leftover fragments. Bag up the plants and throw them into the rubbish. As always, stay safe and wear protective clothing.

Introduced to the US in 1917, giant hogweed is listed as a Federal Noxious Weed, and it's illegal to import or move between states without a permit. 

It's restricted for good reason. Its toxic sap causes photodermatitis, making skin incredibly sensitive to sunlight and resulting in painful rashes and blisters.

If sap comes into contact with the eyes, it can cause temporary or even permanent blindness. 

Although similar in appearance to poison hemlock, giant hogweed towers over its shorter cousin, growing 6.5–10 feet (2–3m) tall.

Its white, umbrella-like flower heads top hollow stems that feature large, jagged leaves. It often grows near streams and rivers.

As giant hogweed reproduces only via seed, the best approach to stop it from spreading is to prevent it from seeding by repeated mowing or cutting. Small areas of seedlings can be pulled out by hand.

As always, wear protective gloves and clothing when dealing with toxic plants. The blisters caused by hogweed can cause permanent scarring or staining of the skin.

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