En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
 
rate this answer
Not Yet Rated

Friday - April 26, 2013

From: Decatur, GA
Region: Southeast
Topic: Invasive Plants, Non-Natives, Herbs/Forbs
Title: Invasiveness of Cosmos from Decatur GA
Answered by: Barbara Medford

QUESTION:

I have been searching for an answer concerning the invasive plant Cosmos. I know that Florida declares this but I have not been able to find out does Georgia? And specifically,is it only the yellow Cosmos or all Cosmos found in nurseries?

ANSWER:

The only member of the Cosmos genus, member of the Asteraceae family, in our Native Plant Database is Cosmos parviflorus (Southwest cosmos). Since the Lady Bird Johnson Wildflower Center is committed to the growth, propagation and protection of plants native not only to North America (excluding Mexico) but to the area in which it is being grown, in your case, DeKalb County, GA, this would not ordinarily be in our realm of expertise. However, we are interested in invasive plants and their control, native or not. By the way, according to this USDA Plant Profile Map on Southwest cosmos, it grows in neither Georgia nor Florida, so it seems unlikely that is the plant in question.

So, we went searching on the Internet for a cosmos that had the potential to be invasive and found Cosmos sulphureus, Yellow Cosmos, which is native to Central America. Since you noted it was considered invasive in Florida, we found this article on Cosmos sulphureus in Floridata. This warning is at the bottom of that page:

"WARNING
Before planting orange cosmos check locally to make sure that it is not invasive in your area. In places like Tennessee orange cosmos is naturalizing in "disturbed" areas but so far is not disrupting native plant communities."

Floridata has the same warning on Cosmos bipinnatus, native to Mexico. In point of fact, Cosmos has been so intensively hybridized that understanding what invasive tendencies you observe in any one cultivar or selection is difficult. Hybrids do not breed true from seed, so the seeds you purchase or the plants you buy may have none of the characteristics you may expect, including invasiveness.  

For one last check, we went to the website of the Southeast Exotic Pest Plant Control article Invasive Plants of the Southeast. Cosmos was not on that list, native or non-.

 

From the Image Gallery




Southwestern cosmos
Cosmos parviflorus

Southwestern cosmos
Cosmos parviflorus

More Non-Natives Questions

Shy blooming non-native Crape Myrtle, in Littlestown Pennsylvania
July 25, 2011 - My Crape myrtle has been planted about three years, and reached a height of about 4'. It blooms late July and for the past two years, has only had one or two blooms on it. I have a lot of buds whic...
view the full question and answer

Slow flowering wisteria
May 09, 2007 - We have a young wisteria growing on the side of the house. It began to flower this year for the first time. Whereas my neighbors' wisterias all bloomed in February, ours has only begun to bloom in mi...
view the full question and answer

Bastard cabbage in Austin TX
March 17, 2012 - Not sure if this is the forum to address this; but is there any effort out there to do something about the bastard cabbage taking over Austin? Especially on MoPac where you can hardly see the bluebon...
view the full question and answer

Leaves on non-native Rose Cactus
January 30, 2009 - I have a Rose Cactus (Pereskia grandifolia). The leaves have all dropped off. I was wondering if this is normal in the winter. Also, is the pear shaped fruit edible.
view the full question and answer

Yellow jackets on non-native crape myrtles
September 25, 2008 - Hey Mr. Smarty Plants I have only 1 question. I have several Crape Myrtles that have numerous amounts (alarming) of yellow jacket bees on them. who what where when why etc? Should I be concerned? tha...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center