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

Pruning pink skullcap and rock daisy from Austin
February 06, 2013 - I have some pink skullcap and rock daisy and other plants in my yard that never entirely die back over the winter. Can you tell me what kind of pruning is appropriate? How far can/should I cut them ...
view the full question and answer

Pruning of frost-damaged non-native Sago Palms in Marble Falls TX
April 18, 2010 - I have several large Sago Palms that have partial frost damage, they are part green and part brown fronds. Should I remove the brown leaves? the center of the leaf is green.
view the full question and answer

Crape myrtle in Austin
August 01, 2012 - Please don't bother to answer my question about how to treat a crepe myrtle with sticky stuff falling from it. I just found the answer on your site. Good site, by the way.
view the full question and answer

Possibility of using weeping love grass on property in Keller, Texas
April 19, 2008 - What do you know about "Weeping Love Grass"? We have heard that it does not require watering (once the roots are established, fertilizing, nor frequent mowing. So we decided to plant it on our 2-a...
view the full question and answer

Proper deadheading of non-natives Arabian Jasmine and Crape myrtle from Las Vegas
July 23, 2010 - Advise please on proper deadheading of Arabian Jasmine, and of Crape Myrtle. They are both blooming great but I want to know once the petals fall should I deadhead and will it help them to bloom agai...
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