Pollen is created by plants for sexual reproduction. It is produced by seed-bearing plants and is transferred by air currents, animals, birds and insects. Pollen forms as a powder-like substance that ranges from fine to coarse in consistency. Some pollen types are a contributing factor to seasonal allergies. Pollen is released by plants at varying times of the year, often dependent on when specific plants are in bloom. Birch trees, goldenrod, carya, erodium and ragweed are five common plants that produce pollen .
Birch trees are common in temperate climates. They produce large pollen grains that are carried on air currents. Birch pollen season ranges from February to May. Once the grains become moist, they crumble and are inhaled. Birch pollen can enter your airways and trigger allergic responses such as asthma. They cause other reactions such as conjunctivitis and hives.
Goldenrod pollen is derived from flowers of the same name. These plants are common throughout North and South America. They produce large pollen granules that are carried by birds and insects. Contrary to a popular myth, goldenrod pollen does trigger allergic reactions in people.
Erodium is a weed that produces purple rosettes. It is a common plant in Europe, Asia and the United States. Erodium pollen grains are small and transported by animals and insects. There is no indication that erodium pollen affects allergies.
Carya pollen comes from pecan and hickory trees. These are large pollen granules that are carried by animals, insects and the wind. Some species, such as pecans and shellbark hickory, have been known to cause severe allergic reactions in people. Other trees in the carya family cause only mild reactions.
Ragweed is an invasive weed that lives in temperate climates. It has been known to take over home gardens and landscapes. Ragweed pollen grains are small, fine and airborne. It is responsible for allergic reactions in people throughout the United States. Common problems caused by ragweed pollen include asthma, pinkeye, pneumonia and dermatitis.