Appearance

Ageratina adenophora is a perennial herbaceous plant with rounded stems that grow up to 5 ft. (1.5 m) tall. Stems are often purple.

Foliage

Leaves are opposite and ovate to deltoid in shape, 2.8-4 in. (7-10 cm) long by 1.6-2.8 in. (4-7 cm) wide. Leaf tip is acuminate while the base is obtuse to truncate. It is sparsely pilose on both surfaces with crenate margins.

Flowers

White flowers are held in loose compound corymbs of about 70-80 florets. The heads are about 0.3 in. (6.5 mm) long by 0.24 in. (6 mm) in diameter.

Fruit

Fruits are black 5-angled glabrous achenes, 0.06 in. (1.5 mm) long. Seeds are tipped with a pappus about 0.14 in. (3.5 mm) long. Ecological Threat

Ecological Threat

A. adenophora is a highly invasive plant, tolerating a wide range of conditions. It is common on roadsides and bushland edges, along watercourses, creeks, and wetlands. It can form dense stands, is capable of infesting intact bushland and displacing native plants.

Citation
Winston, R.L., Andreas, J.E., Milan, J., DesCamp, W., Randell, C.B., and M. Schwarzlander. 2014. New Invaders of the Southwest. United States Department of Agriculture, Forest Health Technology Enterprise Team. FHTET-2014-12. Retrieved from https://bugwoodcloud.org/resource/files/14767.pdf
 

Resources

• California Invasive Plant Council - Cal-IPC
• Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS

Selected Images

Maps

Invasive Listing Sources

• California Invasive Plant Council
• Federal Noxious Weeds
• Florida Noxious Weeds
• Hawaii Noxious Weeds
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• New Invaders of the Southwest
• South Carolina Plant Pest List
• USDA APHIS Regulated Pest List
• WeedUS - Database of Plants Invading Natural Areas in the United States

References