10 Worst Plants and Trees for Your Allergies

Hay fever, also known as allergic rhinitis, doesn't have anything to do with a fever. In the 19th century, John Bostock named the condition during the haying season when its symptoms were most present.

Pollen from several plants and trees often brings on hallmark symptoms like watery eyes and a stuffy nose. You may even have some of those plants and trees gracing your yard or neighborhood. Although, typically, those plants don't include beautiful, colorful flowers. With some of those flowers, the pollen is too heavy to be airborne.

Here's what you should know about some of the most common allergy-causing plants and trees and how to spot them.

Plants

The amount of pollen in the air that triggers allergy symptoms depends on the weather. For example, on hot, dry, or windy days, a lot of pollen will be circulating in the air.

Some of the most common plants that disperse pollen include ragweed and grasses. Mostly, ragweed sheds pollen during the fall. In contrast, pollen from grasses often circulates during the late spring and summer.

Ragweed

Where you'll see it: Fields, riverbanks, roadsides, and rural areas

Where it grows: Midwest and Mississippi River basin

Peak time: Summer and fall

"The most allergenic plant we have is ragweed," Warren V. Filley, MD, a fellow of the American Academy of Allergy, Asthma, and Immunology (AAAAI), told Health. "It is less common on the West Coast or in New England. Therefore there is less pollen in those areas." 

About 15% of people allergic to pollen are sensitive to ragweed in the United States. Seventeen types of ragweed grow in North America.

Ryegrass

Where you'll see it: Dry, cool lawns, meadows, pastures

Where it grows: Northern parts of the United States

Peak time: Spring and summer

"There's no allergy-free grass," said Dr. Filley. "And if you mow it, you pick up mold as well as pollen." 

Grasses, as a whole, are often problematic for people with allergies. But some of the most common grasses that cause allergies include:

• Bahia
• Bermuda
• Fescue
• Johnson
• Kentucky blue
• Timothy

Pigweed and Tumbleweed

Where you'll see it: Lawns, roadsides

Where it grows: Western and northern United States

Peak time: Spring to fall

Other weed allergens in the west include Russian thistle and green molly, also called Kochia or burning bush.

Trees

In addition to ragweed and grasses, trees also disperse a lot of pollen that causes allergy symptoms. Mostly, tree pollen is common during the springtime.

Mountain Cedar

Where you'll see it: Mountainous areas 

Where it grows: Arkansas, Missouri, parts of New Mexico, Oklahoma, and Texas

Peak time: Spring

"For the Texas hill country, it does not get any worse than the mountain cedar tree, which causes some of the most severe allergy symptoms I have ever seen," said Dr. Filley.

Maple

Where you'll see it: Along streams, woods

Where it grows: Eastern United States and Canada

Peak time: Early spring

Ash-leaf maple tree produces potent allergens and is found throughout the United States. Other more moderate maples that trigger allergies are the red, silver, and sugar varieties.

Elm

Where you'll see it: Cultivated, wetland habitats

Where it grows: Eastern and Midwestern United States

Peak time: Spring (American Dutch elm) and fall (lacebark elm)

Dutch elm tree disease killed an estimated 60% of the elm tree population during the mid-20th century in the United States. But the trees made a comeback during the late 1990s. Score: one for the environment, zero for your allergies.

Mulberry

Where you'll see it: Woods, river valleys

Where it grows: Eastern United States

Peak time: Winter to summer

Flowering plants don't usually produce the most potent allergens. For example, cherry and crabapple trees in bloom probably don't cause allergy symptoms. However, mulberry trees may contribute to hay fever.

Pecan

Where you'll see it: Woods, orchards

Where it grows: The western fringe of the southeastern United States, northern Florida, Georgia, Indiana, and Ohio

Peak time: Spring

Pecans may taste great in a pie. But in areas with lots of pecan trees, the pollen is one of the most common sources of allergies.

Oak

Where you'll see it: Woods

Where it grows: The coastal plains from Texas to Virginia and Florida

Peak time: Spring

"Oak trees produce less potent pollen but very large quantities," explained Dr. Filley.

Arizona Cypress

Where you'll see it: Well-drained soils

Where it grows: Southwestern United States

Peak time: Spring

The Arizona cypress tree can produce pollen for six to seven months yearly in warm climates.

Mold Allergies

In addition to trees and plants, mold may cause allergies. For example, if your symptoms act up in spring, it may not be due to pollen circulating in the air. Instead, mold levels tend to rise with wet, warm air.

"Not to be left out are the molds, of which there are hundreds, which produce significant symptoms throughout the U.S., depending on [the] time of year and activity," said Dr. Filley.

You can get accurate pollen and mold levels using the AAAAI's National Allergy Bureau tool. The tool measures pollen and mold levels by area.

How To Reduce Pollen Exposure

There isn't a cure for plant and tree allergies. But there are ways to manage your allergies, including:

• Stay indoors, if possible, when the pollen count is high. Afternoons and evenings will have lower pollen counts.
• Wear sunglasses and cover your hair when outside.
• Keep windows closed during peak pollen times.
• Use central air conditioning or air cleaners with certified asthma- and allergy-friendly air filters or HEPA filtration.
• Don't track pollen inside. Instead, leave shoes outside; change and wash clothes worn outside.
• Shower daily before going to bed.
• Wash bedding weekly in hot, soapy water.
• Do not dry clothes on an outdoor line.
• Limit close content with pets that spend a lot of time outside.
• Start allergy medications recommended by a healthcare provider before the pollen season starts.

Treatment for Pollen Allergies

Along with reducing contact with pollen, over-the-counter (OTC) and prescription medications can help reduce symptoms. Those medications include:

• Nasal corticosteroid sprays: These reduce swelling in the nose and block allergic reactions.
• Antihistamines: These relieve sneezing and itching in the nose and eyes.
• Decongestants: These reduce nasal stuffiness.
• Leukotriene receptor antagonists or modifiers: These block chemical messengers responsible for allergic reactions.
• Cromolyn sodium: This is a nasal spray that blocks the release of chemicals that cause allergy symptoms. One example is NasalCrom (cromoglicic acid).

A Quick Review

Hay fever, caused by plants, trees, and mold, commonly triggers allergy symptoms. There's no cure for hay fever. But knowing when the plants and trees near you commonly shed pollen, you can take precautions to reduce exposure. For example, staying indoors as much as possible and keeping your windows shut can help decrease your symptoms.