Maple Pollen: Season, Box Elder, and How to Spot It
September 28, 2026
Maples are trees in the genus Acer, which botanists have moved from the old maple family (Aceraceae) into the soapberry family, Sapindaceae (University of Nebraska-Lincoln Gardens). Many people picture a lobed leaf and a spinning "helicopter" seed, but maple flowering tells a more surprising story. Red and silver maples bloom before their leaves appear, releasing pollen while branches still look bare (NC State Extension).
And one member of the genus, box elder (Acer negundo), fools almost everyone. Its leaves look more like ash or young poison ivy than a classic maple leaf, yet the St. Louis County Pollen and Mold Center calls it "the most potent member of the maple family" for hay fever sufferers (St. Louis County Pollen and Mold Center). Knowing which maple grows near you matters, because their pollen timing is not the same.
Maple Pollen Quick Facts
| Field | Detail |
|---|---|
| Type | Tree |
| Scientific name | Acer, soapberry family (Sapindaceae). Older sources use Aceraceae. |
| Species | At least 150 worldwide (UNL Gardens); 13 native to the U.S. (Pollen.com) |
| Typical season | Late winter through spring, depending on species and location |
| Pollination method | Most North American maples use both wind and insects. Box elder relies on wind alone (St. Louis County Pollen and Mold Center). |
| Pollen grain size | Roughly 22 to 51 micrometers, varying by species (Pollen.com) |
| Time of day | No universal maple-specific peak hour. Weather changes daily counts. |
| U.S. regions | Widespread, especially the eastern U.S., plus street and ornamental plantings nationwide (Lo et al., 2019) |
| Commonly cross-reacts with | Other maples and walnut (box elder data; see Maple Pollen Cross-Reactions) |
Is Maple Pollen High Near You Today?
Maple pollen won't show up in your local Air Quality Index. Intact pollen grains are too large for the PM2.5 and PM10 monitors the AQI relies on, which we explain in How Pollen Affects Air Quality Readings. For daily tree pollen counts, check the certified station nearest you on the AAAAI National Allergy Bureau pollen map. To see air quality where you live, use Filterbuy's Live Air Quality Index Map.
How to Identify Maple Pollen at the Source: Leaves, Flowers, and Seeds
Start with leaf arrangement. Maple leaves grow opposite each other on the stem, two leaves at the same point, facing across. Most maples also have lobed leaves. Red maple, for example, has 3 to 5 main lobes with toothed edges (NC State Extension), and silver maple has 5 deeply cut lobes with silvery undersides (NC State Extension).
Box elder is the exception that trips people up. Its leaves are opposite too, but they are compound, usually with 3 to 5 leaflets and occasionally 7 (NC State Extension). It is the only native maple with compound leaves (University of Minnesota Extension).
Now look at the flowers, because that is where the pollen comes from:
- Red maple produces small red flowers in short, drooping clusters before the leaves appear (NC State Extension).
- Silver maple has small greenish-yellow to red flowers in early spring, also before leaf-out (NC State Extension).
- Box elder has separate male and female trees. Male flowers hang in clusters on hairy stalks, often with red anthers, and these are the ones that shed pollen (NC State Extension). Female trees form the seeds after pollination.
After flowering, maples form paired winged fruits called samaras, the "helicopters" that spin as they fall (NC State Extension). Those are seeds, not pollen. By the time you see helicopters, the pollen release is over.
Bark varies by species and age, so it is a weak stand-alone clue. And a dust film on your car or porch can't identify the source. Maple pollen grains are microscopic (Pollen.com), so settled powder alone never confirms which plant released it.
Maple Pollen Look-Alikes: Box Elder vs. Poison Ivy and Ash
Box Elder vs. Poison Ivy
Young box elder can show three leaflets, just like poison ivy. The key difference is arrangement. Box elder leaves are opposite on the stem, while poison ivy leaves are alternate (University of Illinois Extension). Poison ivy twigs also tend to be reddish to orangish-brown (University of Illinois Extension). Don't touch a plant you can't identify. Check the arrangement from a safe distance.
Box Elder vs. Ash
Both can have opposite compound leaves, so leaves alone may not settle it. Look closely at the leaflets: box elder's end leaflet is often lobed, while ash leaflets are more uniform and never lobed (Minnesota Wildflowers). The fruit is the clearest tell. Box elder forms paired winged samaras (Illinois Wildflowers), while green ash produces a single-winged samara (NC State Extension).
| Feature | Box Elder | Poison Ivy | Green Ash |
|---|---|---|---|
| Leaf arrangement | Opposite | Alternate | Opposite |
| Leaflets | 3 to 5, occasionally 7; end leaflet often lobed | 3 | 5 to 9, never lobed |
| Fruit | Paired winged samaras | Small berries | Single-winged samara |
When Is Maple Pollen Season? Timing by Region
Maple timing depends on species, weather, and location. Maple start dates vary less from place to place than many other tree pollens, and like most trees, they start later at higher latitudes (Lo et al., 2019). The windows below are flowering or pollen-season ranges from named local sources. Treat them as sourced starting points, not a national schedule.
| Species and Region | Typical Window |
|---|---|
| Red maple, North Carolina | January to March |
| Silver maple, North Carolina | February to April |
| Red maple, Pennsylvania | As early as February, through April |
| All maples, St. Louis | February to May |
| Box elder, Minnesota | Mid-April to late May |
Flowering dates are not the same as measured airborne peaks. Check your nearest National Allergy Bureau station for the current year.
Check current conditions for Charlotte or Minneapolis, or find your city on the Live Air Quality Index Map. Our seasonal allergy calendar shows how maple fits into late winter and spring.
Maple Pollen by the Numbers
- 3.7% of all pollen counted. Across 31 National Allergy Bureau stations from 2003 to 2017, maple ranked 10th among the 11 most important allergenic pollen types (Lo et al., 2019).
- At least 150 species worldwide. Maples grow across the world's temperate regions (UNL Gardens), and 13 species are native to the U.S. (Pollen.com).
- Box elder has the widest range of any maple. It grows across much of North America, from coastal plains to mountains (NC State Extension).
- 32 gallons of sap for 1 gallon of syrup. Sugar maple is the only tree used commercially for syrup today (NC State Extension), and it produces pollen too.
Maple Pollen Myths vs. Facts
MYTHBox elder is an elder, not a maple.
FACTBox elder is Acer negundo, a true maple, and the only native maple with compound leaves (University of Minnesota Extension).
MYTHThe maple syrup tree must be the maple pollen source near me.
FACTSugar maple does produce pollen, and its flowers appear to be wind-pollinated even though bees visit them (Nebraska Forest Service). But a local maple pollen count doesn't identify sugar maple specifically. Depending on the season and the trees around you, red maple, silver maple, or box elder may be the relevant species.
MYTHThree leaflets always mean poison ivy.
FACTYoung box elder also shows three leaflets. The difference is arrangement: box elder is opposite, poison ivy is alternate (University of Illinois Extension).
MYTHBees on the flowers mean the pollen isn't airborne.
FACTMost North American maples are pollinated by both insects and wind (St. Louis County Pollen and Mold Center). Red maple flowers are wind- and insect-pollinated (Penn State Extension), so seeing bees doesn't mean no pollen becomes airborne.
MYTHEvery box elder tree releases pollen.
FACTBox elder has separate male and female trees (Illinois Wildflowers). The male trees shed pollen, while the female trees produce the seeds.
Maple Pollen Cross-Reactions
This section is descriptive only and is not medical advice.
Most published cross-reaction data for this genus comes from box elder. Thermo Fisher Scientific's allergen encyclopedia reports that box elder pollen shows high cross-reactivity with other maple species and extensive cross-reactivity with walnut pollen. It lists only limited reactions with American sycamore, cottonwood, birch, English oak, and weeping willow (Thermo Fisher Scientific).
The birch food list does not carry over to maple, and this page cannot predict an individual's cross-reactions from tree identity alone. For questions about symptoms or diagnosis, speak with a board-certified allergist.
How to Keep Maple Pollen Out of Your Home
Because red and silver maples can bloom while it still feels like winter, maple pollen often arrives before people start thinking about allergy season. A few steps help:
- Check local counts starting in late winter. Use your nearest National Allergy Bureau station as soon as maple buds start to swell.
- Keep windows and doors closed when maple is active. Open windows and doors are one of the main ways pollen gets indoors (2023 scientific review, PMC).
- Leave pollen at the door. Wipe down entry surfaces and sills, change clothes after time outdoors, and wipe pets down when they come in. Our spring allergy prep guide has a full room-by-room checklist.
- Match your HVAC filter to your household. MERV ratings measure how well a filter captures particles between 0.3 and 10 micrometers. A MERV 8 filter must capture at least 70% of particles in the 3 to 10 micrometer range, and a MERV 11 filter at least 85% (EPA). Intact maple pollen grains, at roughly 22 to 51 micrometers, are larger than anything in that test. For most homes, MERV 8 is the standard choice. For households with allergies or pets, step up to MERV 11. Our MERV 8 vs. MERV 11 guide breaks down the difference.
- Change filters on schedule. Standard 1-inch filters are typically replaced about every 90 days. Filterbuy 4-inch filters last 6 to 12 months.
These steps reduce how much pollen circulates indoors. They are not a substitute for medical care, and no specific symptom outcome is claimed.
Since maple season can start in January, the best time to swap your filter is before the first warm spell. Filterbuy makes MERV 8 and MERV 11 filters in more than 600 standard sizes, plus custom sizes, so it's easy to find one that fits your system and have it in place before the red maples bloom.
Shop MERV 8 Filters Shop MERV 11 FiltersFrequently Asked Questions
When is maple pollen season?
It depends on the species and region. Red maple can bloom from January through March in North Carolina (NC State Extension), while box elder flowers from mid-April to late May in Minnesota (University of Minnesota Extension). In St. Louis, the overall maple pollen season runs from February to May (St. Louis County Pollen and Mold Center).
Does red maple bloom in winter?
It can. In North Carolina, red maple flowers appear from January through March (NC State Extension), and in Pennsylvania they can emerge as early as February (Penn State Extension). Penn State Extension calls red maple one of the earliest flowering trees in Pennsylvania forests.
Is box elder a maple tree?
Yes. Box elder is Acer negundo, a true maple, even though its compound leaves look more like ash. It is the only native maple with compound leaves (University of Minnesota Extension).
Do only male box elder trees release pollen?
Yes. Box elder has separate male and female trees (Illinois Wildflowers). Male trees carry the pollen-shedding flower clusters, and female trees form the seeds after pollination.
Is box elder pollen worse than other maples?
Box elder is the only maple pollinated solely by wind, and it produces copious amounts of pollen. The St. Louis County Pollen and Mold Center regards it as the most potent member of the maple family (St. Louis County Pollen and Mold Center).
Does sugar maple produce pollen?
Yes. Sugar maple flowers appear to be wind-pollinated, and bees also visit them (Nebraska Forest Service). A local maple pollen count won't tell you whether sugar maple is the source, though.
Is my three-leaflet plant poison ivy or box elder?
Check the arrangement. Box elder leaves are opposite on the stem, and poison ivy leaves are alternate (University of Illinois Extension). Don't touch a plant you can't identify.
Can maple pollen get into my house?
Yes. Pollen comes in through open doors and windows and on clothing, people, and pets (2023 scientific review, PMC). Keeping windows closed on high-count days and running your HVAC system with a clean filter help limit how much circulates.
What air filter should I use during maple season?
It depends on your household. MERV 8 is the standard choice for most homes. For households with allergies or pets, MERV 11 captures a higher share of larger airborne particles (EPA). See our MERV 8 vs. MERV 11 guide to compare.