Dalmatian toadflax and yellow toadflax grow on the side of the road, in grasslands, and among crops. Toadflax has an allergen index of 4 out of 10, making it a moderate allergen. As they crop up in many commonly trekked places, these plants can aggravate hay fever for passersby.
Johnsongrass is a moderate allergen and was originally introduced in the U.S. as a forage crop. Johnsongrass spreads quickly in different habitats, including forests, fields, and wetlands. Johnsongrass causes millions of dollars in lost agricultural revenue in the U.S. every year by invading crops.
Russian knapweed was accidentally introduced to the U.S. via contaminated alfalfa seeds from the Turkestan region of Central Asia. These plants are members of the daisy family, making anyone prone to daisy allergies also vulnerable to Russian knapweed's pollen. This plant can quickly get out of hand, causing infestations that worsen the quality of plants for grazing animals.
Quackgrass grows in disturbed open areas, where natural vegetation has been removed to expose the underlying soil. This plant can quickly become an infestation through rhizomes, which involves plant roots invading the soil. Cutting off the grassy tops isn't enough; the plant’s root system has to be eradicated as well.
Commonly known as mugwort, was originally introduced in the U.S. for use as an antiseptic liniment. Grows in late April and early May, not flowering until July or August. Those who suffer from spring and summer seasonal allergies may not be spared from absinth wormwood—especially since this plant is perennial.
One of the worst invasive species in the world, cogongrass causes ecological and economic damage to forests, agriculture, and natural ecosystems by infesting native wildlife. Cogongrass pollinates through the wind, meaning it can spread quickly as its carried along in the air we breathe.
Mimosa trees are smaller trees, less than 50 feet in height, that often grow with multiple trunks. Bees and butterflies love mimosa trees, spreading their pollen from one plant to the next. This helps the plant spread and can also release allergens into the air and onto other plants insects pollinate.
Palmer’s amaranth is a severe allergen and is one of the most widespread and economically devastating weeds in the southwestern U.S. The plant’s pollen spreads by the wind, which can aggravate allergies.
A prolific pollen producer, giant reed is a moderate allergen and has been introduced worldwide for erosion control, ornamental use, and the production of reed for paper, pulp, and musical instruments. The giant reed is a member of the grass family, which is generally considered a significant source of allergies, and releases its pollen between July and October.
more home & garden: natureofhome.com
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