Pollen Allergens: Reference Pages by Plant and Family

What are pollen allergens? They are the proteins in pollen grains that trigger hay-fever symptoms in people who are sensitive to them. Almost every pollen count comes down to a few dozen plants, and those plants fall into three families — trees, grasses and weeds. Pollen Atlas reports the tree, grass and weed categories daily for every city it tracks, so the fastest way to make a pollen count personal is to know which family — and which plant — is yours. These reference pages collect the common pollen allergens Pollen Atlas reports in depth: what each one is, when it pollinates, where it is worst, and how it appears in the counts. Start with today's readings on the pollen heatmap and the city rankings, then read the family page that matches your season.

Tree pollen allergens

Tree pollen opens the year — a few winter specialists, then the great spring wave from February to May. Pollen Atlas reports eleven plants individually in its city data; the trees in the directory are the ones that drive the tree index. Oak, birch, cedar, maple and the rest each carry their own season and their own strongholds. The tree pollen reference page walks through the full spring cast, plant by plant. The directory's tree cast runs to thirteen plants — oak, birch, mountain cedar, maple, elm, ash, pine, cottonwood, alder, mulberry, olive, pecan and hickory — each with its own window inside that spring wave.

Grass pollen allergens

Grass pollen is the late-spring and summer act. The northern pasture grasses share their allergens and are usually reported together; the warm-season grasses — Bermuda, Johnson — are separate allergies of the South and Southwest. That split is why two people can both have a grass allergy and suffer in different months. The grass pollen reference page explains the two families and lists the grasses in the count. Six grasses make the directory's grass cast: Bermuda grass, timothy grass, ryegrass, Kentucky bluegrass, Johnson grass and fescue.

Weed pollen allergens

Weed pollen closes the year. Ragweed owns the fall in the East and centre; the amaranth weeds own it in the dry West; and the docks and sorrels quietly fill the summer between grass and ragweed. Two weed reference pages are live: the ragweed pollen reference page, covering the fall backbone allergen, and the dock sorrel reference page, covering the grouped panel entry behind so many summer weed readings. The directory's weed cast is short — ragweed, dock sorrel, and pigweed & tumbleweed — but between them they cover most of the weed index's year.

Reading the categories on a city page

Every city page reports the same three categories — tree, grass and weed — as daily indexes alongside the overall pollen index and the day's dominant allergen. The category that is high is the family to read: a high weed reading in September is ragweed's season speaking, a high grass reading in June is the pasture grasses, and a high tree reading in April is the spring wave. These reference pages exist so that when a category moves, you can put a plant's name — and a season, and a region — to the number.

The full plant directory

These reference pages go deep on the headline families and plants. For the complete list — every major pollen type with a photo, its season, its regions and the symptoms it can cause — see the types of pollen directory. Then watch for your plant where it matters: in the daily detail on city pages such as the Houston pollen count and the Tulsa pollen count. If your symptoms and the counts disagree persistently, that mismatch is worth raising with a specialist — you can find an allergist in the Pollen Atlas directory.