Everyone loves a nice tree here and there. They beautify yards and sidewalks and provide homes for animals. However, not all trees are created equal - at least not when it comes to humans' purposes. As you'll discover below, some trees are just not meant to be in your backyard. Some of these trees could cause terrible damage to your property because of weak branch structure, or give off such a horrendous amount of pollen you'll most definitely develop an allergy. Take a look at some of the trees that are better left alone.

While black walnut trees are beautiful and used to make gorgeous furniture, you should be weary of them. The tree produces a chemical called juglone, which is toxic to many other plants. Juglone occurs mainly in the roots and nuts, but can also be found in its leaves in small amounts. The nuts may also negatively affect horses if they are consumed. And if you're an allergy person, black walnut trees will also trigger your allergies as they are known to contain lots of pollen.

The Bradford came to America in 1964 and is native to China and Vietnam. It's absolutely stunning to look at, but don't ever plant one in your yard. These trees are so awful, entire articles and blogs have been dedicated to convince you just how awful they are. The main reason this tree sucks, is its weak branch structure, which means it will rip apart under the slightest of stress and litter your street, lawn, or most likely damage anything near by. They are also terribly invasive because they cross-pollinate with many other pear trees.

Specifically, female ginkgo trees. If you happen to love the look of ginkgo trees, go ahead and plant a dozen. However, make sure they are all male. Female ginkgo trees produce fruit that most people hate. Why? Because it smells like vomit. Yes, while female ginkgo trees are just a beautiful as males, they stink.

There is nothing inherently wrong with these trees. They're pretty and strong, but, as it turns out, something is killing them. The emerald ash borer is a beetle bent on the destruction of ash trees. According to American Forests, tens of millions of ash trees have already been destroyed. So, if you want a beautiful tree that will last, better keep looking.

These trees are quick-growing and great if you want to build a natural privacy wall in your backyard, but be warned, they are extremely high-maintenance. It's disease-prone, especially to canker - a bacterial disease that causes lesions on the bark. It's also prone to leaf diseases and honey fungus, which attacks the roots on the tree and can be fatal. If that weren't enough, this tree is also a bug magnet and quite messy, as it drops leaves and branches frequently.

Everyone can probably recognize a willow tree. They would mesmerize us as kids and were endlessly fun to run through, with its long, weeping branches. These mighty trees come with a price though. Its roots go deep, sometimes winding around sewer pipes and are difficult to control. These trees require heavy monitoring to make sure they don't damage sewer lines.

Eucalyptus trees can be quite the nuisance. They tend to shed bark often, causing lots of litter around the tree. This bark is also easily combustible and could spread a fire quickly if one so happened. These trees also bear the risk of harboring pests with no natural enemies in North America. These pests could potentially kill the tree.

Beware of the Quaking Aspen. These trees don't live long in urban areas and are frequently affected by diseases, like cankers or leaf spots, and pests. They need the soil of high altitudes and are frequently transplanted from the mountains where they don't fare as well. Fun Fact: The oldest and heaviest known living organism is considered to be the Pando root system from a bunch of male quaking aspen trees in Colorado. The system weighs 6,600 tons and is estimated to be 80,000 years old.

Allergy sufferers, listen up. This tree will kill you. Well, not really, but it will make you feel really miserable. This tree is native to the south-central U.S. and releases its massive volumes of pollen in the winter. According to Wikipedia, if severe allergic reactions are left untreated, it can develop into infections, such as pneumonia.

All around the mulberry bush! Just kidding, you wouldn't want to run around a mulberry bush when they are so loved by silk worms and produce fruit that will stain anything it touches. The tree also gives great shade, such great shade, in fact, that other plants may not grow beneath it.