Tall Ragweed • Ambrosia trifida
Conditions: Allergic rhinitis; allergic asthma; allergic conjunctivitis; contact dermatitis.
Symptoms: Itchy, stuffy, or runny nose; post-nasal drip; sneezing; itchy, red or watery eyes; asthmatic symptoms; puffy eyes;
rashes or itchy skin.
Physical description: Also known as “giant” or “great” ragweed, tall ragweed typically grows up to around 6.5 feet in height but can grow as high as 16 feet in fertile soil; stems are coarse, single or branched, and woody at the base; leaves are broad and sparsely covered with small, stiff hairs.
Environmental factors: Wind-pollinated and capable of spreading rapidly, with small pollen grains that are capable of traveling long distances; occurs on disturbed open sites and roadsides; can also be found on low ground and alongside streams, often in waste places; prone to invading agricultural fields and drainage areas.
Cross-reactivity: May be cross-reactive with other species of ragweed, such as western and short; ragweed is also known to be cross-reactivity with a number of fruits and vegetables, such as watermelon, cantaloupe, honeydew melon, banana, zucchini, and cucumber.
- “Ragweed.” Merriam-Webster. Accessed Feb 20, 2020. https://www.merriam-webster.com/dictionary/ragweed
- “Plants Profile for Ambrosia trifida L. (great ragweed).” USDA. Accessed Feb 20, 2020. https://plants.usda.gov/core/profile?symbol=AMTR
- “Ambrosia trifida (giant ragweed).” CABI. Accessed Feb 20, 2020. https://www.cabi.org/isc/datasheet/4693
Did You Know?
Of the approximately 40 species of ragweed, tall ragweed is the largest. Given its size and invasive nature, it is considered an especially problematic weed, capable of decreasing crop yields and impacting native biodiversity.