Elm Pollen: The Encore Adventure

Written by Anne Ambs, Allergy and Asthma Center of NC, Cone Health Medical Group

Elm pollen, often associated with spring, makes a surprising return later in the year. While our native elm species release their pollen during late winter and early spring, one introduced elm species, Chinese elm (Ulmus parvifolia), pollinates in late summer or fall in North Carolina.  Chinese elm, also known as lacebark elm, is a significant source of autumn pollen.

Figure 1. Mature Chinese/lacebark elm tree. "Ulmus parvifolia" by Matt Lavin is licensed under CC BY-SA 2.0.

Belonging to the Ulmaceae family, elm trees thrive across temperate regions of North America, Europe, and Asia. They are commonly found in forests, along riverbanks, and in valleys, where they contribute to the ecosystem by offering shelter and food for wildlife. Mature Chinese elms can reach heights of up to 50 feet and spread to 35 feet wide. Thanks to their adaptability, elms are often chosen for landscaping, valued for the shade they provide, soil stabilization, and their attractive appearance. Their hardwood is notably water-resistant and has been widely used to construct boats, agricultural buildings, and coffins.  In the U.S., those uses for elm wood have historically relied on the American elm (Ulmus americana).  That species of elm was once widespread, but Dutch elm disease has significantly depleted the number of mature American elms available for lumber.  Chinese elm, however, exhibits considerable resistance to Dutch elm disease.

Chinese Elm stands out as a prominent producer of fall pollen, especially in the southern United States. This tree features small, oval leaves and a sweeping canopy. Its bark peels away in flakes, revealing a yellow-orange inner layer.  This distinct bark is the inspiration for the Chinese elm’s other common name, lacebark elm.   Chinese elm foliage changes to purple, red, or vibrant yellow hues in autumn. In warmer climates, Chinese elms may retain their leaves throughout the year, behaving as evergreens. Now used extensively in landscaping, they are a major contributor to fall allergy symptoms, alongside ragweed and other weed pollen (see Figure 2 below). 

Figure 2. A cluster of fall elm pollen (with the exception of the 1 ragweed on the far left) is a common sight for the Forsyth County pollen team this time in late August/early September. Image taken on September 4, 2025, by Forsyth County staff.

The pollen monitor in Winston-Salem, North Carolina, operated by the Forsyth County Office of Environmental Assistance and Protection, has been measuring local pollen since 1997 and first detected fall elm pollen in 2006.  Since then, fall elm pollen numbers have shown a general upward trend (see Figure 3 below).  Many Chinese elms have been planted in this area for use as landscape trees – often planted along roadsides.  Although the U.S. Forest Service considers this elm to be an invasive species in some states (but not currently North Carolina), Chinese elms have proven to be locally very popular as a landscaping tree in urban and suburban areas.  In future years, it will be interesting to see how the popularity of the Chinese elm is affected by the allergenicity of its pollen and its status as a potential invasive species.

Figure 3. Fall elm pollen (from Chinese/lacebark elm) have increased significantly since the Forsyth County Office of Environmental Assistance and Protection began pollen monitoring in 1997. No fall elm pollen was observed before 2006, and the upward trend took off strongly in the 2010s. 

While beautiful in appearance, these trees can be a menace to allergy sufferers causing symptoms including runny or stuffy nostrils, postnasal drainage, sneezing, itchy and watery eyes, throat irritation, and can even worsen asthma symptoms. There are several types of pollen in the air during this period, and allergy testing can determine which pollen or pollens are responsible for individual reactions.   An allergist can help evaluate which pollen (or other environmental factors) are causing allergy symptoms with skin testing or blood testing.  The most common environmental allergy testing includes grass pollen, weed pollen, ragweed pollen, tree pollen, molds, dust mites, dog, cat, and cockroach. Once the culprit, or culprits, have been identified, a comprehensive treatment plan can be formulated. Allergy symptoms are largely controlled with over-the-counter antihistamines and steroid nasal sprays. However, if medications do not provide relief, allergen immunotherapy may prove to be an effective treatment option.